GBA Logo horizontal Facebook LinkedIn Email Pinterest Twitter X Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Plus Icon Minus Icon Picture icon Hamburger Icon Close Icon Sorted

Community and Q&A

Modern (hydronic) heating and what all should start to know as of 2014

wjrobinson | Posted in Mechanicals on

I stumbled upon this site to do with researching an update to a (hydronic) heating system I installed two decades ago.

So much has changed mainly the best change is the access we all have now to information.

This is the best read I have had off the internet to do with modern current (hydronic) heating.

Dana, besides your wealth of help here, this pictorial is great for the visual types like me.

GBA Prime

Join the leading community of building science experts

Become a GBA Prime member and get instant access to the latest developments in green building, research, and reports from the field.


  1. Expert Member
    Dana Dorsett | | #1

    I can neither design hydronic systems nor draw pretty diagrams as well as John Siegenthaler, who has promoted hydronic heating more heavily over the past 20 years than anyone else I can think of. Some of his stuff is arguably overkill, but unlike 95% of the "heetin' an' plummin' " contractors out there, he does the math.

  2. charlie_sullivan | | #2

    Nice resource. One thing I saw there that I hadn't seen before was "micro-circulators", sized one per radiator. Leaving aside the question of when that makes sense, does anyone know a source for micro-circulators? I'd like to take a look at them and see whether they might be useful in some special cases.

  3. jinmtvt | | #3

    Thanks AJ for the link ...


    all this goes agasin't its own "simplicity " rule .

    way too expensive in low load homes
    and installation labor + maintenance intensive

    Don't want to sound as the " mini-split" guru ..
    But i fail to see how all this complexity can beat the current mini splits for heating..

    hell if you are afraid of temperature difference just use another 3000$ and get an additional unit installed

    Then, i've worked with numbers on solar heat panels last year, and we discussed this many times before and after Martin placed is famous " Solar thermal is dead "thread ...
    the numbers for Solar heat just don't add up any more compared to PV + heat pump COP

    Now waiting for the big names to bring their water heating air heat pumps from europe/asia to NA ...
    ( why don't we have similar hot water heatpumps as to the current mini splits evades me still )

    At similar efficiency, the cheaper and simpler systems are an easy choice.

  4. user-2890856 | | #4

    Thanks for the comment Jin , But .

    Nothing there is difficult and in fact it all is simple . many people are looking for comfort and comfort my friend is not a number on a thermostat as much as it is a state of being . I for one and many I have designed for don't wanna hear our heat , feel air blowing over us robbing the BTUs we have made naturally and would rather not see unsightly stuff all over the home .
    Solar thermal is dead huh ? Maybe solar thermal for those who never had a clue to begin with is dead , but thermal storage is far from dead . Look up Energy kinetics and thermal battery systems . both in Montana . When you have just enough knowledge to be dangerous contact me . By the way true green folk really would not base everything on first cost , much less equipment whose efficiency rates plunge the colder it gets .
    These easy choices you speak of are only easy for cheap parrots whom heard it from someone with a voice . Not all those with voices are worth listening to by the way .
    As far as Europe and Asia , did you know that over 65% of their heating systems are hydronic Genius ? You just keep being the puppet of the Mechanical Engineer my friend , some of us will exploit nature and use what she gives us effciiently while reaching Exergy . You may wanna look that word up .

  5. fitchplate | | #5

    AJ, I thought you would be on a first name basis with John S. He teaches at Niagara College between Lockport and Lewiston NY. He has a great column in P&M Magazine and his texts are the basis of most HVAC schools' cirriculae.

  6. fitchplate | | #6

    Richard. Times are changing. If I had met Dana or Martin earlier, my house's HVAC solution would have been put together a whole lot differently. I don't much like air blowin' on me either, but the numbers are very compelling and when you can get the same BTU's better than 1/3 the montlhy energy bill, you will have a hard time selling "green as anything other than the cash save on a heating bill.

  7. jinmtvt | | #7

    Richard :

    first i thank you for the new word, not being a native english speaker makes it a "discovery" every time i learn of new words ...although this time i might need to read the wikipedia definition ~ 10times before i understand the real meaning of it !!!!

    Then, what i am referring to are products similarto this :

    Don't think that solar thermal heat systems have a good efficiency during very cold winter time..they don't .

    PV is the same, costs less and still 100% usefull during summer time.

    We all know it is a matter a years before someone develop a dependable and affordable energy storage.

    Do your maths for your situation, but in my climate solar thermal is not and will never be interesting.

    Costs drive adoption ... being GREEN is not about a few egocentric happenings,
    it is about mass installments , where it makes a difference on the planet level.

    The only disadvantage of mini splits is comfort,
    that i agree, a very good hydraulic heating system can be more comfortable without any air drafts,
    but again ..

    for high efficiency we need smaller houses, in which temperature differences is lower and or easier to manage
    High mass inside the thermal envelope aids both sides.

    I'd rather invest a little more on insulation than on a complex hydraulic system that will need maintenance ( whereas insulation will never ).

    And i couldn't care less about what % of european heating systems are ,,,
    it doesn't have anything to do with the discussion and what is available now
    ( unless u have a number to show us on how many heating systems werecomissioned in the least few years which i doubt ..and every country/climate has their own complexities )

    BTW, my personal house has 100% in concrete floor electrical heating ( wires )
    and 4 Fuji RLSH2 minis ( the ones that still work down to -30c )
    so i am fully aware of comfort and thermostat settings complexities ...

    So unless u can setup a 2Ksqft house with full hydraunic heating system, that uses both solar thermal and air to water heatpump setup for under ~ 10k$ ....

    Minis + baseboards or whatever other radiant electrical heating devices you can come up with,
    will still be the current best solution for new reasonnable green houses.

    ( except if you have access to free renewable wood , then a very small super efficient stove can replace as much as u'd like of your heating )

  8. user-2890856 | | #8


    A heating system for a house as tight as we discuss here for under 10K is a snap . Grid tied PV is a great thing but when they meet the 30 by 30 or 20 by 20 numbers you and others will no longer be of any use to the utilities and there will be no money for free scheme . Here's some math for ya , it will still always take 29,291 watts to equal 1 therm . If you are not running solar Pv you probably receive your electric at a 90% less than transmission loss and unless you're receiving that generated by hydro or wind there is fuel being used to generate it . So the same unit of Ng that heated your house may be used by the utility to generate 29.291 Kw but by the time it gets to you it is only 2.9 Kw . But who cares it's not your money , and by the way , to quote Joe L . " It's about the energy stupid " Go ahead feeling all warm and fuzzy with the lie , someday , maybe you'll figure it out .
    Maybe I can clear up Exergy for you . It's the endeavour to allow the energy used to do the most work possible using the least amount of effort . Does losing 90% of the energy converted at the source by the time it reaches you sound efficient ?
    If you for a minute think that the grid is free you're a fool . you believe solar pV is something else huh ? Maybe you can explain to me and others how it is such a deal when N. Tesla pulled electricity from the atmosphere and wanted to distribute it to all for free . Wait a minute , we cannot get paid for that they said , destroy it all . You are quite the sucker huh ?

  9. fitchplate | | #9

    Richard ... I am all ears. If you can make me feel better about my regretted HVAC solution, I would be obliged. But your description is cryptic and general, and might assume some of us know more than we do. Can you please walk though your calculations and principles more carefully, point by point, comparing the options. I am in a cold climate about zone 6) with high heating costs so I am open to being educated with better alternatives.

  10. user-2890856 | | #10

    What is your climate Jin ?

  11. user-2890856 | | #11

    FlitchPlate ,

    My email is [email protected] , use it . my phone number is 732-581-3833 , you can use that also . My intent is not to educate the world . Quite to the contrary though it is to attempt to slow the flow odf bad advice and uneducated statements and misinformation .

    I never assume what anyone knows or that they know anything at all , I just respond to commenst and try to set the record straight . I fully understand the damage done by plumbing and heating contractors everywhere and why the technology that John S and myself promote is looked at the way it is . Fortunately for those of us who promote this there are worldwide studies appearing regularly that show the real numbers when stacked up against other technologies . Now , if we can educate the next generation of dsigners / installers we can save the consumer form stupid design and manufacturer myths .
    What was your regretted HVAC solution by the way ?

  12. kevin_in_denver | | #12

    Response to Charlie Sullivan,

    Here's my current favorite micro pump:

    Response to Richard McGrath: Please direct us to more information on zero energy homes that are heated and cooled with hydronics and/or solar thermal. Make sure system cost information is included.

  13. Expert Member
    Dana Dorsett | | #13

    Richard: I'm not sure what the source of all that invective is, but active solar "efficiency rates plunge the colder it gets" too- even more so when they're covered in snow.

    The expense of solar thermal hydronic systems can be pretty daunting. On new construction there is usually more comfort to be had (and true it's definitely not the number on a thermostat) by pouring that money into a high performance building envelope, at which point mini-splits (or tiny wood stoves) point-source heating becomes pretty viable. Mini-splits at low speed are barely audible (about as loud as the circulation pump on my radiant floor zone), and are not some tepid wind-chill high cfm blast either. A few degrees of higher air temp in a high-R house buys a lot of comfort- more than it would in a lower-R (read "cooler average radiant temperature) house.

    While it's true that most residential heating systems in Europe are hydronic, I find little evidence of that being the case in Asia. I'd be extremely surprised if Asian home heating was "...over 65% of their heating systems are hydronic Genius..." the way it is in Europe.

    Hydronic air source heat pumps that work at reasonable efficiency exist, but are also pretty pricey, and many won't cut it at cooler Canadian or US-upper-midwestern design temps, but compared to active solar of comparable cool/cold weather performance they still offer favorable price/performance suitable climates.

    Solar thermal may not be completely dead, but it does have competition, and the cost curve on the competition is gaining ground. Ever-better-cheaper heat pumps leveraged by ever-cheaper PV has already put many solar thermal solutions behind the eight-ball. Solar PV is rapidly become a mainstream commodity, and will only become ever more so in the coming decade as it drops to the buck-a-watt (installed price) level. The number of moving parts and potential points of failure of grid-tied PV and ductless heat pumps are small relative to most solar thermal home heating solutions, and both the up-front and lifecycle costs can be lower too, even in 2014.

  14. jinmtvt | | #14

    mr Richard,

    first off, i do live on hydro electricity ( Quebec ..) but this has not much to do with the current discussion.

    Zones i work with are 6-7 ...

    Dana could explain it better, but my guess is that most grids aren't going to be as "dirty" as you propose in the near future.

    Could you please list a current system for under 10K$?

    Last time i checked, sealed tubes solar thermal panels weren't exaclty free.
    Then you'd need a second energy for nights etc..which one are you pushing for ?

    what's up with Tesla ???? why do you bring this in ...
    You start to sound like "Terry " :p ( sorry Terry ahha )

  15. charlie_sullivan | | #15

    Kevin: thanks for the link to the micro-circulator. Here's a company that has the full line of those, with a little more data.

  16. Expert Member
    Dana Dorsett | | #16

    BTW: " 29,291 watts to equal 1 therm"

    I'll assume that means watt-hours, not watts, and it's actually (100,000/ 3.412= ) 29,308 watt hours, if 100% efficient (resistance heaters) but leveraged at a seasonal COP of 3 in a mini-split it's only 9,769 watt-hours, if measured at the meter, 10,855 watt-hours at the primary tap of the first transformer at the power station, assuming 10% grid losses.

    A therm of gas burned in a boiler is not 100% either, and has the additional energy burden of grid pumping & control power.

    Natural gas burned in a combined cycle gas plant is about 50% thermal efficiency from fuel to load, assuming a 10% grid losses.

    A better class mini-split will run a COP of about 1.8 at an outdoor temp -10F even when running full blast,. better than that if it's modulating at a lower speed. That's the source-fuel to heat-delivered equivalent of a 95% efficiency gas fired system, maybe better, depending on how carefully the hydronic designer was on reducing pumping & control power.

    The seasonal COP average that you'd in western Montana would be about 3 (even using the early "FE" series Mitsubishi units, which are about 15% less efficient than the newer "FH" series, as monitored tested by Ecotope in-situ in occupied homes in Idaho Falls ID a few years ago, sample size N=12), there's no way a condensing boiler can even touch that source-fuel efficiency, since it's well north of 100% fuel BTU-in to space heating BTU delivered.

    In coal-heavy US grids with older ~30% thermal efficiency single-cycle coal baseload power it's currently somewhat cleaner to go with condensing gas than with ductless mini-splits, but with newer combined cycle coal it's something of a wash on a greenhouse gas basis. But if the externality costs of high carb fuels gets built into the price (either through a carbon tax or other means) they rapidly become the highest-cost form of new electricity, and there is a strong financial incentive to retire them. Even without those externality costs applied new-coal doesn't compete well with midwestern wind, and even new combined cycle gas (at the current historically low gas pricing) is neck-in-neck on lifecycle cost with new wind. And wind (like PV) is getting cheaper year on year, though not at the same rate as PV. Wind is currently cheaper than PV, but that will not be the case in a decade (barring unforseen technology breakthroughs on wind equipment cost & efficiency.)

    Most US local grids are not 100% thermal coal. Of all kwh shipped on US grids in the past couple of years coal (new, old and in-between) accounted for less than 40% (and generally shrinking. In MT over half of all kwh shipped was either hydro or wind, as of 2012: Even if ALL of the rest of the power on the state's grid was 30% thermal coal (which it ain't), heating with mini-splits would be somewhat lower carb than heating with condensing gas boilers. Even if MT only barely hit's it's EPA assigned grid emissions targets,whatever that carbon footprint for mini-splits is today, in 15 years it will be 21% less. But it's likely that MT will beat that (and soundly), independent of the approach taken to compliance: But a condensing gas boiler in 2030 will have about the same emissions profile per MMBTU as one installed this week.

  17. user-2890856 | | #17

    I'm sorry Dana . Did I once mention a boiler of any sort for the purpose of this discussion ? Quick question , would an air to water heat pump operating in 0* conditions be more or less efficient than a thermal storage tank feeding a wtw heat pump with 33+* fluid ? Funny you should mention Montana , big things happening in Montana . IGSPHA is upset with Colin Wunder and James Schenk . See it seems that they have been doing multi source heat pumps in homes in Montana and Wyoming and New Jersey . Please take the time to actually view the attached link .

    For the less technically savvy .

  18. user-2890856 | | #18

    Also sorry about the math faux pas . When you have the same measurement on 2 sides of an equation I cancel them out . However , based on your response I gather that you readily figured that out but hardly see the need to have pointed it out . BTUh , Kwh . Hours cancels out in a mathematical standpoint . You are very intellectually superior , I'll give you that . I also apologize for the invectivness that you sensed although that was not my intent , i did not realize you and others may be so sensitive . i will do my best in the future not to offend anyone's sensibilities . however , throughout the remainder of this discussion i will be frank and straight to the point . It may get uncomfortable and I apologize to all in advance . I will prepare some math which will substantiate my points , some will include Ng appliances and others will not . There is lotsa stuff that needs discussing and some uncomfortable truths for some of the present company . REMEMBER , this is all about conservation and future well being of the citizens of this rock . Please correct me if I am mistaken about our goals and how this all became important . The lies , truths , deceptions and market spin .

  19. GBA Editor
    Martin Holladay | | #19

    At one of my first full-time jobs, I was hired by a plumbing wholesale house to design hydronic heating systems for heating contractors. Hydronic heating systems are efficient and elegant when properly designed, and are often a good way to heat a large building.

    For residential applications -- especially for green homes, which should be small -- it's usually hard to justify the high cost of a hydronic heating system. Boilers, circulators, and hydronic distribution systems cost more than simpler heating systems, and they aren't a good match for air conditioners. That's why it usually makes more sense to spend the money that might have been spent on hydronic heating equipment on a better thermal envelope for the house.

  20. wjrobinson | | #20

    Dana, for me in my area, there are applications for many types of heating systems. Also I have customers who prefer one over the others. And there are homes here that go from cabins up to mansions. You should see some of the utility rooms set up like you're in the basement of a high rise, hotel or hospital.

    And I have a friend who just installed a three floor radiant system. I love radiant in a basement if it is to be living space, could be radiant panels, floor etc.

    Natural gas used through a condensing modulating boiler works best if done with low water temperatures such as radiant floors or oversized radiant panel heaters.

    My friend with the new three floor radiant set up has the same temperatures in the home from the basement all the way to the peak of the 26' high cathedral ceiling. It's his choice for a home, and it's quite nice. Of course I love what Marc Rosenbaum does and is teaching us all about.

    Another blog with some related posts etc....

  21. wjrobinson | | #21

    Dana, how about a natural gas cogen motorized heat pump... COP of 3 plus capturing the heat from the motor running...

    Anyway the point of my posting this "question" is that in twenty years I now have new choices when I replace a boiler and the circulators.... Grundfos Alpha's and Taco delta T circs now are neat and can be more efficient and do neat things... Modcons can work well with my old radiant install... I can do outdoor reset, I can do higher heat output to get a floor warming then drop it down.... I can change temps at the modcon instead with a mixing valve if I want to

    One thing many don't do right is get the return temp down for modcons to come even close to their rated 95% rating via condensing...

    Here's a problem I see with my friends set up... it condenses as we have collected it in buckets... but his set up has no way to ramp up the system to full burn if the floors have been off and the temperature has to rise from 50 to 70 for a weekend visit. Right sizing heat systems has changed the thinking for what to do with rarely visited second homes. The Temps need a day to rise in homes set way back with radiant or small heat systems.

  22. GBA Editor
    Martin Holladay | | #22

    Lots of radiant floor systems (especially systems with tubing embedded in concrete) suffer from the slow response time problem that you mention. When rooms get too hot, they are very slow to cool; when rooms are cool, they are very slow to heat.

  23. wjrobinson | | #23 is a great site, Dan Holohan is the man...

    just noting this site for those that have not wandered into it...

  24. wjrobinson | | #24

    Martin slow response is a problem for superinsulated mini split homes too when set back to 45-55 for vacation homes.

    We solve it many ways... via the internet, going by to raise temp for them... and more... many just don't want to leave the temp high if gone for days to weeks...

  25. wjrobinson | | #25

    The two radiant floor installs I deal with have no problems with over or under heat if they leave the temp set. The customers also love the systems. They like the lack of air blowing and the lack of units along the baseboard too. Many of us in my area do not air condition, we have lakes and swimming and ceiling fans, lions and tigers and bears oh my or actually raccoons and fisher cats and wild turkeys oh my...

  26. Expert Member
    Dana Dorsett | | #26

    Richard: "Did I once mention a boiler of any sort for the purpose of this discussion "

    It's really hard to parse what your actually trying to say but you suggested that Jin should "Look up Energy kinetics...".

    Energy Kinetics is a manufacturer of gas & oil fired steel boilers outfitted with heat purge controls and buffer tanks.

    What's really unclear to me is what is meant by "...manufacturer myths ..." or "The lies , truths , deceptions and market spin ", or "Go ahead feeling all warm and fuzzy with the lie , someday , maybe you'll figure it out ." If you have something of content to say, it's being obscured by attitude.

    The notion of using large low temp water tanks as thermal buffers is not new (Harvard University did near zero energy house based on a very large solar buffer tank back in the 1930s), nor is using the heat of fusion of water as energy storage ala Wunder & Schenk. While there may be some cost advantages over traditional GSHP solutions, and increases solar thermal collection efficiency by ~50% or so, it's not at all clear that it beats mini-split + PV solutions on $/MMBTU. The efficiency of pumping heat out of 32F water/ice is higher than pumping it out of 0F air, but that's ignoring the efficiency & lifecycle cost of putting that heat in the buffer, as well as the very high efficiencies that modulating air source heat pumps achieve when it's above freezing out (which is most of the heating season.) If you can pencil out the system cost (including design, since they are all custom designs), it would be at least a starting point for a substantive discussion on the merits of the approach. The number of necessary system components & heat exchangers seems high, but Wunder & Schenk seem to think it will reliably beat GSHP systems on cost, despite buried 2000+ gallon buffer tanks.

    I'm fond of Rube Goldberg contraptions that work at decent efficiency (like my own hydronic heating system I retrofitted into my 1920s antique), but in new construction there's usually better bang/buck putting the money into a high performance building envelope (the components of which are longer lived & near zero maintenance) than putting it into overly complex hydronic systems.

    AJ: " about a natural gas cogen motorized heat pump... COP of 3 plus capturing the heat from the motor running..."

    The original concept behind Marathon Engine was a natural gas engine directly driving a heat pump, but they have since moved on to a strictly micro-cogeneration (no direct drive heat pump) solution.

  27. fitchplate | | #27

    After leaving it at 55 F for a weekend, my TT boiler driven panel radiators warm up the place in minutes; returning it to a livable temp using <110 f supply temps. it gets heat into the place a lot faster than lighting wood stove.

    I can happily attest to the benefits of an obsession with a caulking gun and dense packing cellulose. Last weekend I allowed myself to run out of propane and waited 3 days to fill the tank: with no auxiliary heating, we had about a 4 F degree drop each 24 hr period. Lows were in the mid 20's. I am sure I am benefiting from some mass storage of heat in the 8" - 12" think cellulose filled walls and ceiling.

    But the f.....n propane was 2.40/gal (current NY state average). Meanwhile electricity dropped from 30 cents/kwh to 26 cents last month. I am thinking to upgrade my basic $70 Grundfos circulators to Alphas.

  28. user-2890856 | | #28

    Flitch , wait till Q1 2015 and obtain the most versatile circ that can be had . This new Taco offering engulfs every other ECM circs performance curve . Same money also . Look up . Don't know about NY programs but in Mass and othet states these and other ECM circs are eligible for a 100.00 rebate . Making most of them right around what PSC , single speeds cost .. The new model is VT2218 . Remember planck's statement in his papers from before any of us were here about the second law ,"Frictional pressure never does positive work " .
    What's your reset curve on that thing ? At design and say 40* ?

  29. wjrobinson | | #29

    The Taco is on shelves now, I am playing with one and an Alpha right now.

  30. fitchplate | | #30

    Richard, I will gladly look into the Taco and the rebate options. Thanks

    As for "What's your reset curve on that thing ? At design and say 40* ?" I don't know how to figure that out. If you see my comment below today's new GBA Blog posting: "Energy efficiency is narrowing the stupid/hurt gap", you will see just how stupid and therefore hurt I am when it comes to my hydronics (and a few other things).

    I guess resistance to admitting my lack of knowledge at the time of designing and building would be considered frictional pressure. I am up for some postive work.

    The only curve I know about is the "learning curve":

    1. First there is "unconscious incompetence" (e.g., Flitch building his house)
    2. Then "conscious incompetence", (e.g., Flitch reading GBA after building his house)
    3. Then we work to have "conscious competence" (e.g., other people explaining to Flitch how he can apply new knowledge and save energy costs by revealing his ignorance on GBA)
    4. And finally, there is "unconscious competence" (e.g. the others on GBA straightening out Flitch when I don't even understand what is revealed about me and my house by my posts)

  31. fitchplate | | #31

    AJ ... I would rather see those little 'coons smiling into the camera than pancaked on the road. Just keep 'em off my roof.

  32. user-2890856 | | #32

    Flitch , Great answers , I like it , honesty that is . You say your panel radiators bring the house to temp in short order and keeps it toasty using 110* fluid . At what outdoor temp though . Your home has infinite heat loads at varying outdoor conditions so you can vary those SWTs automatically using a reset curve which in your case is built right into your boiler , I think , I will read previous to confirm . This shoulde certainly be utilized in your case because the colder the Entering water temps at your boiler the more efficient it will perform . The key to this is changing the emitters output to as closely match the heat loss of the building at any time . Are you running the same water temp at all conditions or are you utilizing the reset ? If you are using the ODR feature then you should fine tune it to optimize performance of the entire system .
    The frictional pressure comment was not meant to point out anything other than Delta P pumps or constant pressure pumps do much less for you than a Delta T pump . Frcition and / or reynolds numbers mean a great deal ,more for heat exchangers ( GSHP , TXV , FPHX) than for mechanical systems which interact with another system which for this discussion we will call a reservoir ( the air in your home ). Example : If your pressure pump is flowing an amount of water at any temp and the return water is coming back at a lower Delta T than the entire system ( emitters , boiler , circs) was designed and sized for it is flowing too much fluid . It is not performing the work we designed it to do . Delta T is a number , a very important number in fact . It is the answer to the universal hydronics formula . So if you used a 20* Delta T to size the emitters and circs and figure out the proper flows at different design conditions and you are getting water back to the boiler at 10* lower temp your system is not operating as designed . Energy can only depart from an emitter at a rate that we have no control over , the reservoir will only accept heat at a rate that is completely dependent on the Delta between the air surrounding the emitter and the fluid temp within it . As that Delta narrows after the mechanical system s turned on the heat transferred begins to lessen . It is at this point that the Supply and return Delta of the fluid starts to narrow which means you did not deliver the energy that the system changed from one form to another . The Delta T pump has sensors on the supply and return pipes and regulates flow dependent upon the programmed Delta T thus keeping the flow much tighter throughout the cycle . In short if your pump is using energy to flow water at a rtae that does not allow the mechanical system to transfer the energy at the designed for conditions it is wasting energy . Whilst a Delta T and a Delta P pump have identical energy requirements to operate the Delta P pump is much less efficient because it is not performing positive work . That is Exergy and the old saying , " you can't fool Mother Nature all rolled into one . Delta T pumps also don't care what the temps are , only that the Delta remains as close to constant as possible.

  33. fitchplate | | #33

    AJ ... photo of the big racoons at my cottage :-)

  34. wjrobinson | | #34

    Delta P circs the Alpha selfs sets up to your system. Or it can deal better with a system that has one circ feeding multiple zones modifying it's wattage to less when less zones call. Being an ECM motor it uses less wattage than a typical 007.

    The delta T unit also favors multiple zones on one circ and also saves lowers the wattage draw being an ECM motor.

    If I have any of this goofed up, I will correct it after Richard takes a peak at it.

    Siegenthaler shows many set ups with less pumps and more zone valves, which like he says many hydro gents install lots of pumps... pumps pumps and more pumps... primary secondary tertiary quaternary, quinary, senary, septenary, octonary, nonary, and denary loops... oh my..

    Flitch nice pic, makes me want to pet the nice bear..

    So Siegenthaler has unlimited info online, this latest PDF chats up modern systems for super insulated low energy homes.

    Very interesting as there are very few if any high tech installs around here in affordable homes.

  35. user-2890856 | | #35

    John is a very smart man and has many texts that support my facts on Delta T . John does not regularly comment on either technology either . A simple question is this , If we design for a specific Delta T , size for a specific Delta T , why would a Delta P pump be more appropriate for a heating system ? I can post heat load calcs for any individual house at many different conditions using many different emitter types . In all of these , flows , pressures , head , temps all change . One thing is always a constant , I'll give you three guesses what that parameter is .
    I also have a quote from Upton Sinclair that everyone may want to think about when quoting industry professionals and this is very important . " It is impossible to get a man to understand something when his paycheck depends upon his not understanding it " I have everything John has ever published in my shelves . While he often refers to Pressure pumps if you thoroughly read his writings and know the equations and understand the laws of thermodynamics , they support my position . By the way , I warn anyone who starts to explore the laws that if you are thorough it will chew up the better part of your entire next year and you'll still only know a bit .
    Let's look at it this way everyone . BTU is based on the universal hydronics formula . If your system is 50,000 BTU you should be flowing 5 gpm at Delta of 20* , 10 gpm at Delta of 10* , 2.5 gpm at Delta of 40* , so on and so forth . Anything other than these rates will put your source out of sync with your system . PERIOD . Your rate of heat transfer will not match the rate at which the equipment is changing energy from one form to another . End of discussion . For a further explanation of differences between the 2 technologies Google John Barba . It is really very simple .
    I am quite familiar with the document you posted Aj . Do this exercise , Go through it and see how many times you see Tr , Tw T this T that , then count the Ps . fact is the only real pressure that concerns me is the worst case head so I can insure my circ can perform properly at all conditions . Net positive suction head Required and available . At different temps pressure will change , at different flow rates pressure will change , fact is the Delta T pump does the same thing as the Delta P with the exception that what it is reacting to is ACTUAL system conditions as they are related to performance . The system is telling the pump how it is performing , what better messenger could there be .

    look through these , go back several Barba blogs and it will all become clear . No mumbo jumbo , just the facts

  36. GBA Editor
    Martin Holladay | | #36

    You're losing me. You wrote, "BTU is based on the universal hydronics formula. If your system is 50,000 BTU you should be flowing 5 gpm at Delta of 20*..."

    I'm guessing that "BTU" is a typo, and you meant to write "BTU/h." But who knows?

    If this is going to be a technical discussion, we need to distinguish between BTU and BTU/h. I hope.

  37. user-2890856 | | #37

    Martin ,
    Sorry for the confusion . But in my defense I thought I was among peers whom understand the definition of BTU " the amount of energy required to raise one pound of water one degree F in one hour " . the hour is understood . No typo . we need not get all consumed with language that is clear and should be known , maybe that is the problem with these discussions . I am at present preparing a sample Ph standard house for whomever wishes to take part please feel free to design a system and include installation , operation costs for a year . Let's put this thing to bed . By the way feet in pressure calcs used to include pounds , since pounds appeared on both sides of the equation always we cancelled them out , now we just have feet pressure . Maybe we can all agree that it really is not necessary to put /h after BTU since a BTU is inherently inclusive of the hour

  38. Expert Member
    Dana Dorsett | | #38

    Martin- Don't correct him about units or he'll give you a paragraph of why it should be obvious, the way he did with me earlier in this thread when I commented " I'll assume that means watt-hours, not watts..." ! :-)

    At the risk of drawing more complaint (and violating my own advice :-) ), BTU is a static unit of energy that is not at ALL time dependent: A BTU is amount of heat it takes to raise one pound of water by 1 degree Fahrenheit, whether it took three centuries or three nanoseconds. BTU/ hour is a heat rate. We certainly can NOT "...all agree that it really is not necessary to put /h after BTU since a BTU is inherently inclusive of the hour." , since BTU is not in fact "...inclusive of the hour...".

    The notion that "When you have the same measurement on 2 sides of an equation I cancel them out " works, but that is not what you in your watts-to-therms equivalence, since a therm is a fixed amount of energy independent of rate, whereas a watt is power- an energy rate. The fact that you also mis-keyed or got the watt-hour to BTU constant wrong made it even more confusing, which is why I felt the need to be explicit about what I assumed you meant by that.

    Sometimes the " per hour " can be inferred, sometimes not. A therm is not a therm per hour, a watt is not a watt-hour. There is a certain clarity about using more precise language, especially when you' re not really showing the math, where the reader can carry the units forward, even if the writer doesn't. Ever seen Ziggy use BTU when he means BTU/hr? Some in the hyrdonics biz will use BTUH to indicate that it's a rate (and hourly, not per minute or second or day) skipping the " / " to save their carpal tunnels, which at least distinguishes it from a fixed unit of energy.

    I personally also find it easier to follow when there are paragraph breaks.

    I'm still looking for the evidence that over 65% of Asian homes have hydronic heating system. (I suspect it's closer to 6.5% in Asia, where point-source heating/cooling seemed to dominate in my personal experience.) I'm sure there are luxury condos houses with radiant floors, but when I worked in Korea kerosene or electric space heaters (or sometimes molded charcoal blocks in a 5-gallon steel bucket propped up on bricks) were far more common than radiators. I can't recall seeing even even ONE home with radiators or baseboards, but it's been a couple of decades. I've never seen them in private homes in Japan either- pretty much the Korean point-source approach, but without the charcoal blocks. (Charcoal blocks as a space heating & cooking fuel seems pretty common in China, more common than in Korea.)

    A penciled out cost estimate of one o' them ice-battery + heat pump + solar thermal systems would also be pretty interesting. I have no doubt that they work, and I can believe it's cheaper than a straight-ahead drilled GSHP solution, but I'm still a bit skeptical that it beats the upcharge on a "Pretty Good House" or better with a coupla mini-splits (or even a Daikin Altherma) and some PV on upfront cost. (I'm even more skeptical on a lifecycle cost basis.)

    According to the crayon-math on my napkin the latent heat of fusion storage of 2500 gallons of 32F water is about 30 therms, which is enough to get a not-too-lossy house through a few dark days of low solar-thermal input, but pumping the heat in & out still takes power, and no matter what the COP of the heat pump is when pumping heat out of 32F water/ice ( probably ~4, maybe 5 if the designer is really stingey on pumping power), if spending the difference in money on the building envelope cuts the heat load in half the ductless solutions wins (on both seasonal power use and upfront cost, without even getting into maintenance & lifecycle cost calculations.) Applying the complexity of a system like that to a Pretty Good House makes less financial sense than it would on house that really can't be heated reasonably without room-by-room balanced or zoned heat distribution. Cost-wise it has to beat drilled GSHP (which runs about $9K/ton in my neighborhood- I've never seen a system come in under $20K, and damned few under $30K), which makes me think there could be a retrofit market where the math works, given the daunting cost of deep energy retrofits on building envelopes compared to hitting those performance levels on new construction.

  39. user-2890856 | | #39
  40. exeric | | #42

    Richard McGrath,
    At the risk of saying something painfully obvious, the main reason not to show "attitude" in human to human interactions is that everyone makes mistakes. When a person makes a mistake, whether its you, me, or the other guy and its harmless and not part of an on-going problem, then I generally just let it go. Life is too short. But when a "genius" like you is intent on nailing people, then you better be perfect from then on. Otherwise you will never be given the benefit of the doubt. I would have thought you would have picked this idea up since you are no longer a child, (I presume).

  41. fitchplate | | #43

    Gentlemen ... please don't lose the constructive direction that will help the unstudied (but not completely stupid) readers like me. I read John Seganthaler many times in the past but he’s technically beyond me and its just not my field of work. I read the Seigenthaler URL posed by AJ and I read Tacos white paper on variable speed drives and I reread what you are talking about, Richard, re: Delta P vs Delta T. Some of it I get and some will take some more and slower explanation of principles and performance variables. I really appreciate Dana' frequent analysis re: comparing technologies and real life pay back calculations (i.e leasing PV’s will help but I want to reduce the need for electricity and fuel before I make it myself).

    As with many reading this site, I am stuck with a practical matter and cannot make a radical retrofit. In my case I have an oversized 120,000 BTU boiler, a TT Excellence, for 1200 sq ft conditioned space with 4 zones, 11 panel rads, driven by 4 (apparently already out of date) Grundfos circs (i.e. they are not ECM and not variable speed smart pumps). I am soon to retire and I will be on a reduced and fixed income. So every dime saved is important.

    I want to tweak and retool my hydronic system now (before retirement) to keep my electricity and propane costs to a minimum. Just like folks emphasize optimizing the envelope (air sealing and insulation – which I have done in spades) I also want to optimize the heating system I have, not the one I should have put in. It was AJ’s posting, Seigenthaler’s power point, and Richards posts that shone a light on some possibilities of reducing both power and fuel consumption

    In theory at design temp of -10F, I need 18 BTU’s/sq ft/hour for 72*. My HVAC designer/installer would not believe the calcs so he oversized the system. I have to rely on all your good judgment and sell sheets on the web, that replacing my Grundfos circs with variable speed, smart, high efficiency pumps like the Alpha or BumbleBee will make a practical dent by reducing operating costs (i.e. fewer watts to distribute and regulate the heat) and make my boiler work more efficiently (i.e. less fuel to maintain the desired temperatures).

    If Taco’s VT2218 is able to improve electrical efficiency by as much as 80%, that is pretty significant. Fuel saving on top of that would be a real bonus.

    AJ - what did you pay for the VT2218. The Alphas are about $175 right now.

  42. krom | | #44

    My semi informed guess, is that you will want to ditch all those pumps for one ECM pump, and zone valves of one sort or another.

  43. user-2890856 | | #45

    Flitch ,
    You need storage to stop the bleeding and short cycling . You need to be able to make that energy do positive work . So your load at design is 21,600 , this number is still above the low end modulation of the installed TTs burner . This is not good . Do you make hot water with this boiler also ? Your complete repair of the installed system does not have to be at aprice that is crazy .
    My comments on these sites are for the purpose of helping folks fiw bad systems and to help others whom are contemplating hydronic systems to make good choices . Besides those , my goal is also to possibly help would be designers / installers to learn what things are truly important so they can identify that a manufacturers rep seminar on a piece of equipment is just that and has little to do with application based knowledge .
    If you are interested in tweaking your system to get the most out of it you can contact me to discuss.
    Eric ,
    Your points are well stated even with the un necessary derogatory comments . This goes all ways and I will not be combative . However , you must realize that mistakes in the form of misinformation on a site such as this effect the integrity and value of all statements . I am not perfect and never stated that this was the case . What I am is technically sound and deal with facts , and , no I don't deal well with folks pointing out grammar , formatting errors and /h to muddle the conversation .
    The fact that I have the chutzpah to say what I mean and mean what I say as opposed to attempting to be clever is of no consequence to me . The idea that anyone would point out my humanity and say nothing of others snide comments is troublesome . I have no idea of others backgrounds or their knowledge base and when I point out that someone's information may be incorrect I expect not to be berated for doing so . some people here have gained beneficial knowledge from my posts and have dodged bad advice . I'm happy with that . Maybe everyone should fact check their information before posting to papers by labs and other industry interests and at a minimum , take them for what they are .
    I will continue to be me and speak frankly and controversially in my ongoing attempt to assist those who search for the truth about many numbers of things .
    I apologize in advance to those who may not appreciate my frank nature .

  44. wjrobinson | | #46

    Flitch, the Alphas for you would save money and would work well as direct replacements or you could drop down to one Alpha and zone valves which is where the Alphas really save energy.

    Post pics of your set up, start a thread and maybe a few of us can help.

    As to Richard saying your modcon is bad he is wrong in my mind, you have one of the best modcons made IMO. It has great turn down. You also should be using outside set back.

    The easy switch for now is to an ECM circ. The delta T will according to the man. save much more than an Alpha but I think in some cases no so much. If you have one Alpha on four zones and you run much of the time with one zone calling, it will be running at very low watts.

    Alpha online $156 Taco bumble bee $185 online $195-210 supply house if you are not a large purchaser.

    Taco Flo Pro university for education... John Barba

  45. jinmtvt | | #47

    The problem is that you started the attack by saying that mini splits are not cost effective/energy efficient/green ( call it as u wish ) and that a hydraunic system fares better in efficiency and comfort.
    While most of us may agree on the comfort issue ( although in a super insulated house it might not make as much of a difference )
    you have gave us no proofs of your sayings.

    Where is your system setup example with pricing and efficiency ??

    It is very easy to find numbers and extrapolate for minis,
    well because there are far less variables in this system.
    The installtion and operation is also quite simple compared to a circulating/solar thermal balbal system.

    So justify a more complex and costly system, the effeciency and comfort will need to be up by quite much.

    While you can be as frank as you can , which is a good thing,
    it does not mean you are right .

    Please post your maths for the efficiency vs other type of systems,
    i am surely not the only interested reader!

  46. Expert Member
    Dana Dorsett | | #48

    The mere presence of Kyung-Dong Boiler/Navien in Korea or Rinnai in Japan, and the fact that they make hydronic heating equipment (among their vast array of other fossil-burners) does not make hydronic heating anything like the norm in those countries. If you do an images search on the words...

    home heating japan do see SOME radiant floor, but most of it is point source heaters such as kerosene, electric or fossil-fired wall furnaces.

    A search on...

    home heating korea

    ... shows some radiant floors, even (way down the line) some radiators, but also charcoal bricks, electric-blanket type pads for sitting on, and space heaters.

    It's not a statisitcal breakdown, but gives me the impression that yes, just as in the US rich folks will heat their homes with radiant floors, but the average home is heated with point-source heating.

    To be sure, as expected, an images search of...

    home heating europe

    ...delivers mostly images of radiators and radiant floors, in stark contrast to what is seen in first-world Asian country name searches.

    I finally figured out why Richard was using wattsinstead of kilowatts for the metric to British unit conversions- he was thinking in terms of power (watts, BTU/hour) whereas I has assumed he was talking about energy (kilowatt-hours, BTU.) Since electrical energy is billed in kilowatt-hours, no watt hours maybe I should have inferred that. A watt is energy rate measured in time units of seconds (joules per second). A kilowatt-hour is whole lot o' joules, an unwieldy number, which is why kilowatt hours is normally used for billing, not joule.

    But that only points out the confusion that occurs when using units of power on one side of the equation, and units of energy on the other- it's sometimes hard to know if the writer is talking about energy or if they intend to be talking about power (energy rate). There is a constant to convert watts x hours or kilowatts x hours to BTU, but if you are dividing out the hours on each side of the equation you end up with watts (or kilowatts) on one side, and BTU / hour (sometimes abbreviated BTUH by hydronics pros) on the other. For those chutzpah to actually say what they mean., perhaps it's wise to actually say what they mean, and not equate power t& energy in their notation.

  47. wjrobinson | | #49

    Dana, we need you and Richard here at GBA. Somehow figure out how to laugh and post with each other.

    You even called me out about my 5 cent mini heat... you know what I mean and so do any others who have interest.

    Short cut language is here to stay... LOL

  48. jinmtvt | | #50

    Dana , check the prices of panels on solar bvd website..
    i've seen some 240W @ 0.55$/w ... many now under 0.75$/w
    getting there!

    with the enphase micro inverter,this brings us dangerously close to 1$/W panel and inverter cost now!

  49. user-2890856 | | #51

    a little patience please Jin . I stated a few comments ago that I was developing a Ph type house for us to use as a model so there can be an apples to apples comparison of first cost , energy utilization and life cycle cost . I state ahead of time that " the house as a system" theory should be taken into account in all aspects . I am positive that my true goals will become crystal clear no matter how muddy other technologies may or may not appear proceeding . There will certainly be alot of math involved .
    i asked Martin to provide the model some time ago . I believe he thought I was looking for a free design to build a house honestly . Now I will find the time in my busy schedule to do so and we can begin . Maybe we should start a new discussion beginning with the heat loss details and family information whom will inhabit our fictitious house . What say you all ?

  50. user-2890856 | | #52

    Aj ,
    I did not say that Flitch's boiler was bad . Tt is a fine product . I said that the low end modulation is right around his design day heat loss . This means that there is little chance that this boiler will ever run long enough to be as efficient as designed to be . in short , it will short cycle damn close to all the time . While Alpha pumps will save you electric use at the same rate as Delta T ECMs , they will not enhance how your source and system convert and deliver the energy you spent your money on , They are efficient in only one way whereas the Delta T pumps increase your SYSTEM efficiency . remember , if you don't deliver what the boiler made your efficiency goes down .
    Flitch's boiler could benefit graetly from a few reasonably priced additions that will allow him to benefit from equipment as opposed to being penalized .

  51. user-2890856 | | #53

    I will locate the other % numbers , but they are a bit harder to get . Please don't disregard this decade old paper though , maybe you did not see it in a previous post .

    Please also remember that Asia is huge and includes dozens of countries .
    will include the most recent numbers soon . They are quite current .

  52. Expert Member
    Dana Dorsett | | #54

    Richard: The ASHRAE Journal paper statement that,

    "In Korea 90% of residences are heated with underfloor heating systems." a completely incredible number, as in "not really believable", or utter crap. I suspect (but don't know for sure) that at least 10% of residences in Korea (and probably way more than that) have no heating system whatsoever. It wouldn't surprise me if 90% of Korean homes with hydronic heating systems have radiant floors though- extra-cushy in that culture since most people sit on the floors at home, (as in Japan.)

    It may be true that urban Korean high-rise residences built since 2000 have under floor heating, but I don't know that either.

    I haven't been in 90% of Korean residences, but 0% of those that I HAVE visited had under floor heating. I have a nephew currently working in Korea who has spent the last three years there. I probably won't see him until next summer, but I'll be curious as to what his take is. This article rings true with my direct observations:

    I fully understand the scope of Asia. Most Asian homes have no heating system at all, let alone hydronic heating systems. I suspect hydronic heating may be the standard in urban Kazakhstan (Soviet era legacy technology), but in Afghanistan mini-splits (where there is a power grid) or small stoves/fire pits are the standard. Most of south Asia is more interested in air conditioning than heating, and get by with point source heating. I've seen dozens of Hindi movies in the past couple of years, and I DO notice mechanical systems in film- even rich folks in India don't have hydronic heating, but they sure have air conditioning! In high-rise urban China there is substantial hydronic heating, but most homes in China are unheated, except for portable space heaters. (In parts of China I've spent time, the charcoal-in-a-bucket or electric space heaters seemed to dominate, and most people just hang out at home with heavy coats in winter.)

    If you limited the discussion to only homes with CENTRAL heating systems, that by definition rules out the vast majority of homes in Asia, and very large fraction of homes in Japan & Korea, and clearly rules out those homes heated with mini-splits (which are quite numerous.)

  53. user-2890856 | | #55

    Dana ,

    Look up the recent side by side study done by Infosys of their building in Hyderabad India . The study contains first cost , through changes in both sides and energy usage for 3 years . It also includes some other interesting stuff .
    Fact is and what I am trying to point out that over the years and as some (very few) hydronic guys have added a good knowledge about the buildings in which they are installing , several ways to use hydronics and radiant have been developed . The reference to overpriced elaborate control strategies in my opinion comes from guys allowing the men whom supply them with materials tell them what they need . This compiled with the fact those supply house gents don't know how to enter the information on the heat load calcs was how we got this notion that it has to be out of range of most . I fully intend to highlight this , I think you for one will be surprised . No matter what fuel we use it must be used effectively , that come from design .

  54. GBA Editor
    Martin Holladay | | #56

    I lived in South Korea for 6 months. The traditional heating method in Korea (known in Korean as ondol) is based on the hypocaust system -- that is, snaking horizontal flues under the floor. Koreans like warm floors, and usually sleep on them.

    The weather in Seoul is similar to the weather in Boston. Winters are cold and snowy.

    The traditional ondol floor, fed by coal briquette burners located in outdoor courtyards, have given way in most cases to modern hydronic radiant floors. I can't verify the 90% number, but it doesn't surprise me. Virtually all Korean homes I visited in the 1980s were heated, including the inns (yogwan) that were built in the old, traditional style. It's hard to imagine that many Korean families would be willing to give up the pleasure of sleeping on a heated floor during the winter.

  55. krom | | #57

    Feel free to use my house to model, just let me know what I need to send you! I'm still struggling with deciding how to heat it.

  56. jinmtvt | | #58

    Richard: please start a new thread with all the info revelant to your model
    this one will be hard to follow on for newcomers in the future

    I can't wait to see what you will come up with,
    but at the same time i wonder....

    a complex system that needs to be specifically adjusted and designed per case?
    How do you propose you get that to every houses working properly ?
    How many GSHP failed to deliver because of the bad design/installtion/tuning ?

    Simplicity is key.
    Almost impossible to scew up a mini split installation
    ( even more so with the recent pre-charged units ...i succeeded with no prior experience in any refrigeration work on multiple occasion with much basic toolings )

    So the design efficiency of this type of installation is going to be stable and repetitive
    whereas a circulating + boiler+ solar thermal system would be very much dependent on many many uncontrollable factors.

    Lastly, a simple solution is also very easy to upgrade/replace in the future.

  57. jinmtvt | | #59

    Just fiddled with my electric bill.
    After a recent raise of price from Hydro Quebec,
    and their fixe prices and stupid redondant taxes
    ( yes we pay fooookin provincial and federal taxes on a gov owned power provider... )

    i end up paying 0.088$ CAD / kwh

    much more than the "annouced ~6cents/kwh"

    i guess we stopped having some of the last expensive electricity in NA a while ago ....

  58. rsmith02 | | #60

    Just a quick reply on heating sources in Asia. Here in Japan I've seen one hydronic heating unit. It was in a hot spring resort and directly fed by underground hotsprings, no boiler necessary. It was unusual enough for the Japanese I was with to comment on it. I said I had a similar system when I lived in New England but it ran on natural gas. It looked foreign to them.

    There is underfloor radiant heat here though I haven't seen much of it. I believe some is fed by air to water minisplits. More common are unvented kerosene stoves and in modern homes, businesses and hotels, ductless or ducted minisplits. Given the sky-high price of natural gas and global oil prices, ductless minisplits are cost-effective and Japanese companies make and market them. I recently bought a Fujitsu Nocria X aircon and as of early Dec. have yet to spend more than 50 yen a day on heat.

  59. user-2890856 | | #61

    This may very well be the problem . Manufacturers and the industries have been making things so easy because there is such a lack of education . This exists in mechanical and building industries . We both are plaqued with proper design and installation . This problem is compounded when you take into account that the average age of the SKILLED labor force in this country is 52 and there is a lack of new blood coming in . This is going to be compounded as our infrastructure is crumbling and a whole bunch of 50 somethings are getting ready to retire , who will rebuild . education has been lacking for quite some time and that is the other or should I say the main personal goal for me , educating consumers and new guys on how things should be done when they are chosen .
    It does not matter which technologies we choose , the thought that when any utility damn near corners a market that they will share the wealth or pass on the savings is a fairy tale . They are greedy and could care less about the end user . Whether you use GSHP , NG , electric , solar , wind , does not matter . The thought that when you add water into the mix it becomes expensive is amazing .
    The air , mini split industry continues to compare to hydronic and reach a level of comfort provided by hydronic heat . There is a reason for this . Mitsubishi just developed and will be vigorously marketing a new sensor to be used with their systems . It senses the Mean Radiant Temperature at the exterior walls and windows and will run until that is satisfied . It seems as if they are continuing to try to mimic or achieve what hydronic systems offer . It also seems that as time goes on the units keep getting a bit more costly also .
    Look up studies that are recent . VRF vs Hydronic , VAV vs hydronic .
    Please let me add everyone that every house is different and has a best solution for that house . I try to figure that out for every home whose plans I am tasked with looking at and design around that . Boiler plate systems are a terrible idea , especially when the only thing they are based on is first cost .

  60. wjrobinson | | #62

    OK, we have talked about this and that.... talk is cheap is the saying....

    Time for actual built examples with costs and pics and schematic drawings.

    Let's compare some reality here.

    Dana, you have some great numbers on mini splits... Richard we need some numbers.

  61. Expert Member
    Dana Dorsett | | #63

    Martin: Most of the Korean homes I visited weren't that old- but perhaps some of them had the ondol type heating systems (I was basically living out of hotels in my 3-4 month stint there.) Of what I can remember there were both electric and fossil fired space heaters, mostly permanently fixed in place, like wall-furnaces. I saw several homes that appeared to have no permanently fixed heating, but had portable kerosene or plug-in electric space heaters, which was also how the factory offices were heated.

    Ondol heating may be under floor, but it's not exactly hydronic heat, eh? ;-) I' hazard it's not central heating doing the whole house, or thermostatically controlled either. (I'd be surprised if any 2 story houses in Korea with ondol first floors have anything like it on the upper floors.)

    The private Japanese homes I've ever slept in all had a single space heater (kerosene or propane) in the main living area, and electric-blanket type mats over the tatami to cuddle on top of while watching ridiculous game shows on TV, no central heating. IIRC one had electric heat in the bathroom (but not the heated toilet seats I've read about. :-) )

    I have no problem conceding a comfort edge to radiant heating (either radiators or floors) in conventional houses as compared to ductless heat pumps, but concede nothing to hydronic fin-tube baseboards, which are predominantly convectors, with very little radiant output. Radiation isn't the only way to increase the mean radiant temperature: In high-R houses with high performance windows the mean radiant temperature is already at or near the room temperature on all surfaces. In those houses the additional comfort of even radiant floors is pretty subtle (unless you take your socks off when it's at the 99% outside design temp.) The additional expense for that extra bit hint of cush is typically pretty high relative to ductless heat pumps.

    In new construction spending the money on best in class hydronic heating systems rather than on the bujlding envelope usually ends up with a higher energy use, higher maintenance system. Even at 2x the efficiency of a mini-split (the thermal battery type hydronic heat pump + solar systems won't hit that), it won't trump cutting the heat load by half.
    AJ: The NEEA has really done the in-situ third party tested efficiency numbers, as well as the customer satisfaction numbers on mini-splits, and the new generation stuff is even more efficient.

    I'm not saying it's an ideal solution for every situation, but for high-R houses it's hard to beat on price/performance. I've spent a lot more for a lot less retrofitting cushy hydronic heating into may not-so-high-R antique, but it's still a lot less money than a deep energy retrofit would have taken. In new construction I'd have opted for a different solution. Retrofitting a mini-split into my mother's place (displacing the original ducted hot air solution) was a no-brainer, buying a lot in increased comfort AND saving a lot of money on heating costs (and giving her quieter better more efficient air conditioning to boot.) The open floor plan made up for the not-so-high R values for making that work. To retrofit a hydronic system into her place would have had a price tag at least 4x the price, and with her fuel options it would have cost more than twice as much to run. Sure, radiation would have been somewhat more comfortable, but not $15,000+ USD more comfortable, with much higher fuel & maintenance costs too.

  62. DIYJester | | #64

    I have a hydronic system and it seems the biggest cost is actually the boiler, zoning and design. The tubing is actually dirt cheap. As far as the zoning and controls, with a little know how and controls/programming experience you can easily create a control system based on Arduino or Ruby Pi microprocessors. I can't comment on the efficiency to run as the A$$hat that built my system insulated the floor, but "forgot" the insulation.

  63. PAUL KUENN | | #65

    PV junk prices

    Those prices are for Chinese PV garbage on the roof top that you'll have warranty claims problems in the future. I've installed PV over many years and most of that new stuff cannot be trusted.

    I can vouch that mini-splits don't work in our area. Most winter nights 0-15F and you'll need a back up heating system to run most of the winter. Air does not blast our but the make up air off the cooler floor will always cause drafts and dust bunnies to dance. Yuck!

    Don't forget the utilities will love you as you're signing on to them for life and the price will ONLY go up! My solar thermal version is free far before a mortgage is paid off.

    I'll say it again, here near Green Bay, WI 4 thermal panels (4x8') tilted at 70 degrees (because we're not stupid enough to mount them flush on a roof) so the snow sluffs off immediately will get two 70 gallon tanks to 150 degrees in one day of "moderate hjgh cloud" sunshine. With a properly insulated house like ours, that buys you two days of very warm floors. Viega system running at 95 degrees F.

    No tubes in a slab, that's a waste of heat. Under the wooden floor or using a "Warm Board" or the like so the floor is warm in 15 minutes and feet are toasty and happy.

    Simple, easy to do and won't take money from the vacation fund. Guess it doesn't matter as we like to play on cold and snowy glaciers for fun:)

    It's simply too bad that most builders DO NOT know how to build...


  64. user-2890856 | | #66

    Thank You Paul Kuenn . Proper design , well thought out and simple installs are hard to beat . Solar thermals do real good on the ground also , saves money on mounting hardware , labor and on the occasion that snow would stick to a panel placed at the proper angle it'll be easy to clear being on the ground . Nobody has yet to read and be creative and / or think outside of the box . Life cycle costs , first costs , solar pv , grid tied because we all need to help the utilities that have treated us so fairly and been so generous . Start thinking more about site derived as opposed to site generated folks .
    Let's think really green and figure out how to get rid of all the bad stuff , refrigerants , chemicals , all of it .
    i must admit , I had a different idea about green when I first heard about it a long time ago . can someone tell me when this movement became about how to build green homes as cheap as possible . How about getting rid of or at a minimum not contributing to heat island effect . How about not letting low hanging fruit such as tubing in your driveway to collect energy in the summer and make most if not all of your hot water , yes you can even make a drainback driveway . Everyone is so interested in selling the wares of the industries that have profited from what you despise and build these types of homes to combat it is amazing . All they have to do is tell everyone , we're sorry , we'll work harder to make newer products that are better , oh and by the way can you put these panels on your roof and help us make some energy we can sell to your neighbor and when the systems need repairing you're on your own . Is Passiv Haus really passive ? I don't think so .
    home details for our experimental budget house will be up this week , sorry for the delay but I do have a 60 hour job . Thanks for your patience and your participation . By the way , who will be designing and specifying this home ?

  65. jinmtvt | | #67

    Paul : most PV panles in reasonable quantities are now at around 1$/w from the bigger vendors,
    and some are USA made ( example SHARP etc.. )

    Have you ever done maths on how much energy your thermal panels are gathering ?
    If not please do so now .... would help greatly to compare it to your total insolation to get an idea of the efficiency of your system.

    Are you running a drain back or closed system ?

  66. jinmtvt | | #68

    Paul :
    if i am not wrong in my off my head maths...

    shows approx 1.2kw/h per m2 per day of insolation

    your 4 panels make up for approx 11m2
    and the temp raise of your 70gal should represent approx 11kwh
    something is not right
    cause this would mean you are getting near 100% eff out of your solar thermal panels :p
    gimme some numbers so i can find my error!

  67. user-2890856 | | #69


    What is not right in your opinion? His system could be quite capable of raising 140 gallons of fluid 55* if in fact it ran down to thermal equilibrium . 140 x 8.33 x 55* =64,141 . Solar fractions for properly designed and installed Solar Thermal systems in the mid 90% range are not uncommon .

    Caleffi system NAS300621P8 for instance is a 4 panel (4' x 8") system with a 120 gallon storage capacity that is SRCC OG300 Certifiedand has an Energy Star Solar Fraction of .97 . this system can and does produce 128,000 BTU per day . I pay app. 16,800.00 for that system .
    What is so hard to believe and why is it that everyone that is a regular on this site questions everyone about everything ? There are many technologies out there and many of them perform in excess of what some here predicate them on . as I have said many times , what you have seen and think is the norm is not simply because 90%+ designs and installations are improper .
    This should be named Green Building Advisor , Missouri edition .
    Maybe with the numbers I have provided you can find your error , I hope this helps . Everyone is not data logging , some folks find it easy enough to compare what they are used to paying against what they pay now simply by looking at usage and bottom lines on their utility bills .
    You may find it interesting to know that direct sunlight is not necessary on the panel to heat water either .

  68. GBA Editor
    Martin Holladay | | #70

    You wrote, "Minisplits don't work in our area. Most winter nights 0°-15°F and you'll need a back up heating system to run most of the winter."

    Even if you aren't exaggerating about the frequency of temperatures between 0°F and 15°F, it's very easy to design a ductless minisplit system that operates quite well in the climate you describe. There are two important steps:
    (a) Choose a cold-climate minisplit that is rated down to -13°F, and
    (b) Size the system properly, so that the output of the unit(s) at -13°F is adequate to meet the home's design heat loss.

    Of course, if you didn't follow these simple system design rules, it wouldn't be surprising to learn that you are disappointed with the results.

  69. GBA Editor
    Martin Holladay | | #71

    Solar thermal systems work. I have one on my roof.

    The only problem is that when it comes to space heating, a solar thermal system isn't cost-effective. The number of BTUs collected each year is too low to justify the high cost of the equipment.

    Moreover, these systems collect lots of BTUs when you don't need them (June, July, and August) and very few BTUs when you need them (November, December, and January).

    But these systems work.

  70. user-2890856 | | #72

    Sometimes I buy lots of a certain product when the price is right for later use Martin . Figuring out how to store those items is the key . Everything does not have to come from Europe although studies from Germany have shown that energy can be successfully stored and used later . Right now I am working on another form of passive collector that will serve 2 purposes . There are several products out there operating efficiently right now that are scoffed at by many . Funny thing is that they work in the real world and have been shown to perform when installed yet people still laugh . Mt thought is that a melding of technologies without cost being the deciding factor is what will be necessary to secure a safe future for this rocks inhabitants .
    I get the impression that a certain amount of things you did back in the seventies were kinda looked at like what myself and my brethren are looking into, that look would be , what , are ya kidding me you hippie . turns out many years , possibly decades later you were on track , who'd a thunk it .
    Grid tied stuff is not the answer , you're more of the way there than most . Now if you could only capture , cage and use that energy when you need it most . Some folks may have some ideas about that .

  71. jinmtvt | | #73


    look at this:

    this is pretty typical curves

    during summer time one might achieve high efficiency,
    but during winter time, when your panel is something like 60c and the exterior air is -10c,
    efficiency is much lowered.

    so it is impossible to get that much energy during the heating season, in cold climates.

  72. user-2890856 | | #74


    This is a very interesting chart . But as this man Paul told us nothing of what technology he is employing to convert this energy to heat , or what type of panel he has , the chart is of little use to us . At 52% efficiency as your chart shows he could still heat his house as he stated since it would require only 64,141 BTU to raise his tank temp from 95* to 150* . Also remember that he stated that amount of stored energy could heat his home for 2 days . he also stated it performs this way on a day with high cloud sunshine so performance and collection could be higher . The key here is to optimize any system whether it be PV , STHW , mini split .
    I would also point out that this chart is very vague . Is this an overcast day , sunny day , what besides temp are the conditions under which the test device is operating , whose panel is this that is being used , what angle and at what position on the globe ? Hardly scientific and should probably not even be considered .
    I also point out that this panel is 158* F at an outdoor temp of 14*F . The numbers actually match his statement , he stated 150* tank temp and the panels are operating at 158* , factor in HX penalty and the numbers work . Thank you for your contribution . Again I will show the math , 140 gal x 8.33 # x 55* ^T = 64,140 BTU .

  73. wjrobinson | | #75

    Jin, that is an interesting site

  74. user-2890856 | | #76


    I know why you linked to the chart you did but why not mention this part and others ?

    Stop cherry picking data , you could have easily included the link to the site and directed us to an area or provided link to your chart and the site . I would say on a global level this would make a monster impact . it makes me question how many may or may not stand to gain by pushing mini splits . Could it just be a fact that getting more less than ideal equipment is the short sighted goal and we'll do better retro fits later ? Have we gotten to a point where the industry is compromised to a point that best is just too expensive so we'll settle ?
    Earlier in this thread I believe , i mentioned this type of technology . Would anyone who has been involved in this discussion disagree that this brings the cost of thermal down in the initial phase while making the PV more efficient .

    For discussions such as this we all need to be transparent and look at the whole big picture . The second link clearly shows that 1,450 KWh per year were saved per residence if you average it . Boy , that solar thermal sure does suck . I am not here to be RIGHT , just to attempt to show other options that are more in line with our goal . Depending what our goal is .
    Jin , why don't you tell us who you really are so maybe we can find out , "who Jin is " as opposed to a Mortal Kombat character from a video game ? We already know Dana has an in depth background in electrical and Martin has been doing this since before it was cool , I have been saving real people , real money and energy for the better part of 2.5+ decades . My goal is Righteous with a bit of self interest mixed in but I do employ electrical sources when they fit the system being designed . Who are you JIn ?

  75. jinmtvt | | #77

    Richard :

    first off.. Jin is a fictional character from a video game yes..but it is from Tekken serie, not Mortal Kombat ( damn did i play MK1 at the local arcade when it got out back then .. ahah )

    Then who i really am is of not much interest.
    Suffice to say that i am not ( yet ) a professional in the building industry, but i am going to be if i can finish my current project and move on.
    What i am for now is someone that is extremely interested in learning as much as possible on efficient building and design, and i have learn as much as one can, daily, from this very website
    for ~ 2 years now ( and i thank everyone here for their participation to this great community )

    Now let's get back to topic because who i am is not very interesting.

    I linked the chart because it looks clean, and shows similar data to the few hundred others i have found over the internet in the last year or two, while learning about solar thermal.

    The reason why i am questioning Paul energy statement,
    is that my quick maths showed for nearly 100% efficiency in capturing insolation which got me tricked up quick to look up to what i had missed in the past.

    You say 140 gal x 8.33 # x 55* ^T = 64,140 BTU
    which translates to ~ 18.75kwh
    ( i hate BTU ... just does not seem to mean anything for me :p )

    my quick math was : 250l X 45k^ x1w x1h = ~11kw
    ( i assumed 45k from 20c up to 65c )
    am i doing something wrong in my water energy math ?? probably ..please correct me on this

    but this error only pushes my argument further

    Paul did not state a date for his example,
    so i assumed december

    again same link :
    this site shows 1.15kwh/m2 of insolation for december at his location
    ( got the correct green bay ? you guys have too many same name cities in every )

    4X 4'X8' panels = 128sqft =~ 11.75m2

    11.75m2 X 1.15kwh = 13kw/h of mean daily insolation
    how can one extract 18kwh from 13kwh evades me

    please don't assume that because one questions something ,
    he is not interested into the matter and or trying to diverge everyone to something else.

    I have no stakes in Mitsu/Fujistu if that is what you wish to know :p

    I was very interested into solar thermal up to a point,
    enough to even consider producing flat panels for all of my future project.
    ( had some quotes done on plated coil and new specialized alum tubbing
    and worked some time with a friend on design for the product )

  76. Expert Member
    MALCOLM TAYLOR | | #78

    Richard, The regulars ask question to find out useful answers. They hope to use those answers to inform the way they design and build. Useful answers include understandable data and practical tried solutions, not promises of future advances that are just round the corner.

    Any perceived "heat" in the discussion goes both ways. Disagreement over the efficiency of radiant or solar thermal seems to enrage proponents that post here. Trying to claim some moral high ground by labelling your actions "righteous" really doesn't further the discussion either.

  77. user-2890856 | | #79

    Malcolm ,
    Not so much trying to claim some moral high ground as opposed to letting this community know that my statements and what I share comes from a good place , it is not to be right . I learn things everyday still and will continue to . My question of Jin was just to help aid me in my decision process whether to continue to engage . Certainly that is not a bad thing .
    I also am not enraged , frustrated maybe , enraged , No . The data is there , the knowledge is there , just trying to share what I know . Unfortunate that so much money is spent on studies and cute little charts to prove / disprove so many technologies as opposed to educating people on the benefits of all there is available . Really just trying to make a difference for real people , not any company , utility , technology . Water just happens to be the device that all other heat transfer methods are compared to , the predicate device as it were , I wonder why that is ?
    I don't think anyone disagrees that radiant is superior , everyone likes the feeling of the sun on their skin to a point . Solar thermal works to , just think , if it did not work really good we would not be sweating sea levels and temps . Come on guys , see the forest through the trees .
    Jin ,
    We don't know either what starting temp was when Paul's panels started to add energy to his tanks . I chose 55*F because after running for 2 days at that 95* according to him would need to be recharged . It is simple to deduce this as he stated this is the amount of time the system would keep the house toasty as it were . I chose 2 High quality panels from an American and a European manufacturer to show the possibility that he was in fact correct . The Caleffi panel has a rated output of 32,000 BTU/day x 4 x .52 (as per the chart you linked) = 66,560 BTU . I'll let you all tell me how many KWh / KW , I'd hate to create confusion . You can dislike the BTU all you want it is here to stay and when dealing with fluid based systems probably should be used since it is used even where the metric system is used . Energy is where you find it gentlemen , it does not require mechanical means to change it's form . Using energy to change energy's form is just plain crazy . This whole thing is about saving energy yet all I keep hearing is how we should use energy to change energy from one form to another to heat and cool our homes . Every energy exchange has a penalty guys .
    Stop supporting the very industries that created the problem and use the energy that is right in your yard . Storage is cool , don't wait for someone else to tell you it is . Spend the money on insulation , then spend some more to insulate a tank and store every (enter your preferred measurement here) of energy you can harvest . You can do it forever and end the madness . Jin , Don't give up on using solar thermal for your future projects and go ahead and make your own panels , it's not that hard as I am sure you are aware of . Just watch where you source your materials .
    Martin , ever read a book from the 70s titled ECOLOGY ? It's a good read , if you have not yet .

  78. jinmtvt | | #80

    Richard: you can keep your BTU if you wish, i see no problem with that.
    I regularly use both metric and imperial systems, daily ..but BTU is not quite used in Quebec
    as it is in the english provinces of Canada.
    I was only stating that an X number of BTU still seems to be a hard grasp for me, compare to a KWh.

    That said,
    The Caleffi panel you are mentionning, the rated output is for what?
    General maximum output ???
    Paul has mentionned his location, i went in a looked for an idea of the insolation he is seeing now probably, i am sure he is not "heating" his house during the summer months.

    Even if you are using the 50% efficiency, you need to explain the rated output of the panels before converting to energy. Surely you know that.
    Every location will see different insolation, thus will yield different resutls nah ?

    BTW, you should not be frustrated at all, unless you have a personal problem.
    Nobody here has insulted you, or said you were a liar as far as i know.
    As Malcolm stated, we are all here to share and learn.
    To do that requires interaction and 2 humans or more...

    And again, as you do not seem to have read my posts completly,
    i am inquiring about this because i am interested, not because i want to push down solar thermal.

    And my background and or experience should not be a deciding factor ( unless i was working for a implied product company : ) for which you decide if you are going to pursue the discussion.

    Again, look up the numbers of insolation per area for his location,
    and please explain to me how you can use a solar thermal panel and get more than
    what is available as solar energy in your system.

    nice quick ref for usa insolation levels here :

  79. jinmtvt | | #81

    Ok searched a bit but found the following :

    from the SRCC

    This is a 40KBTU rated solar panel from Caleffi .

    As i thought, ~40KBTU output is at maximum condition
    ( cold water , warm climate high exposition )

    note this is a 3.5m2 panel and not a ~3m2 ( 38sqft vs 32sq ft )

    so this panel should be collecting something in the ~4K BTU/day during winter

    and this is @ 3.2KWh/m2 daily from the SRCC doc, which Paul location does not get during December.

    Richard look this up and please let me know if i am wrong on something here.

    I might have overlooked something,
    but this is in par with what i found when i was looking at solar thermal vs PV about a year ago.

    don't forget that as you heat up the water storage, the efficiency of the transfer goes down quite a bit

    Fully understand how solar thermal is direct heat, don't worry.
    But it can also be used more directly, through windows, which are kinda required on a building.

  80. wjrobinson | | #82

    I started this thread to discuss modern hydronic heating.

    We should start a new thread to discuss solar thermal use specifically. Most of us that desire knowledge need practical info.

    We need;

    exact installs,costs, equipment used examples including exact pieces and manufacturers, pipe sizes, graphs, heat loads, data we can dig into.

    Data is king and actual installs is key, Just talking it's great is a useless discussion.

    I may need to split this discussion to hydronic heat via modcons and fuel use and to one where solar is added.

  81. jinmtvt | | #83

    It's all Richard's fault dad!!!
    :p i apologize for helping steer this thread AJ :)

  82. Expert Member
    Dana Dorsett | | #84

    Paul writes:

    "I can vouch that mini-splits don't work in our area. Most winter nights 0-15F and you'll need a back up heating system to run most of the winter. Air does not blast our but the make up air off the cooler floor will always cause drafts and dust bunnies to dance. Yuck!"

    Not exactly the right description of how modulating ductless heat pumps really work. Ductless heads take their air from the top side, and direct it downward/across the room at varying rates of speed. While you wouldn't want to park the head where it's blowing directly onto the kitchen table, most of the time it'll be running at the lowest blower speed, wafting a gentle & very quiet 115F-120F breeze across the room. It's nothing like single-speed ducted heat pumps (or fossil burner hot air solutions.) Both Mitsubishi & Fujitsu have models with a guaranteed output level at -13F / -25C, and they continue to operate (at a non-specified output) down into the -20s F. (IIRC Jin reported his Fujitsu units were still putting out substantial heat at ~ -28F or so last winter.)

    Then later: "I'll say it again, here near Green Bay..."

    Green Bay? Green Bay is somewhat warmer than where Jin Kazama is currently heating his house with mini-splits. The " doesn't work here..." argument might be true in Fairbanks (design temp of -41F) or Whitehorse (design temp -31F), but it's simply not factual that you can't heat with mini-splits in Green Bay (design temp -8F) . Reference:

    Also... "Don't forget the utilities will love you as you're signing on to them for life and the price will ONLY go up! My solar thermal version is free far before a mortgage is paid off."

    The utilities? The utilities are themselves in "fear and loathing" mode (or at least some of them are, and others will become so.) Barclays bank has downgraded the utility sector bond ratings broadly, in the face of the oncoming PV tsunami.

    Many utilities will HATE you for putting up PV on your roof, since it's direct competition with them. It's up to the regulators to decide if they can bar you from putting them up or whether you need to pay enhanced fees (both have been tried, mostly without success). Third party ownership of rooftop PV is as common as outright ownership by the homeowners, and is free on day 1, comes with a 20 year power purchase agreement with a discount from the standard utility rates, and all maintenance issues are managed by the solar company. In some states beginning in 2015 SolarCity is offering $0 down 4% 30 year financing deals for outright purchase, comes with a 30 year warranty & performance monitoring too. It's cash positive from the first power bill on, and you get to take the Federal Income Tax credit. I don't see any deals like that on solar thermal, though Jigar Shah (founder of Sun Edison, third party ownership solar company) is talking about creative financing on solar thermal with his new company, Generate Capital Inc. (Full disclosure: I have no financial interest in any of these companies, and though I've not met him, I have a personal friend in common with Jigar Shah, who helped develop the business model for Sun Edison.)

    The "...for life..." issue is also in question. The economics of grid-defection get better with every fee-gouge the utilities apply to PV owners, and in the year-on-year reductions in cost of batteries on your side of the meter. Grid defection makes many uncomfortable, but it's already viable and economically rational in Hawaii and much of Australia. If the utilities make it too painful to stay hooked up, they will indeed be losing that revenue stream.

    The lifecycle cost of PV power (even without subsidy) is already below the grid-retail price in much of the northeastern US, and those costs are falling every year (unlike solar thermal.) There is no such thing as "...the price will ONLY go up..." going up when you're net-metered AND net-zero-energy, except for fixed grid connection fees. If the fees become egregious, unplugging is no longer out of the question.

  83. PAUL KUENN | | #85

    Sorry Gents!

    I'm a 54 y.o. who works long hours inspecting fire apparatus, bike to and from work (16 miles on winter fat tire bike) and xc ski afterwards every night. Now that we just lost our snow:(, I do have a bit time to read and write. As a lifetime member of the MREA, I help alot of folks with PV and solar thermal installations and building pretty good homes.

    I have lots of temp gauges on my solar hot water system and look at it almost every day. That's it. I have 4, 32sq ft. Heliodyne collectors and I have a super insulated house. it's a closed loop system with 50/50 glycol/water at 32psi. Collectors are at 68 degree tilt so snow avalanches off immediately. Loop passes through the external exchanger for DHW tank (50gal.)first then goes to two floor tanks (2x 70gal), one with external and second is internal. All tanks are super insulated as the basement can get to 55F.

    Back up heater for DHW is the Air Gen Tap heat pump and I have a very efficient Thermolec heater to boost the floor water heat.

    Each morning I check temps. Water for floor heating in the tank (before warm floor circulation begins) is usually about 90 degrees from the night before. When I get home and it was a mostly sunny day in November through January the tanks range from 145F to 160F. In summer when the tanks approach 175F, water is sent through a series of basement floor registers as a heat dump and we don't need the dehumidifier all summer as it stays at 72F (basement floor is uninsulated).

    I mentioned most home air heat pumps didn't work in this area as they have warming coils to keep them defrosted and with 27c per KW here in WE Energies territory, it becomes a huge electrical bill. We're closer to Antigo, much colder than GB but who's ever heard of Antigo? That means you're paying billionaires for wasted energy that wasn't needed if the house was built right in the first place. Can you tell I hate utility companies?

    Hope this helps, PK

  84. Expert Member
    Dana Dorsett | | #86

    Paul: Unlike typical ducted air-source heat pump systems, ductless mini-splits do NOT use resistance heaters for defrost- they reverse the cycle and pull heat out out of the house for defrost function. The only resistance coils in the units are tiny heaters to keep the bearing lubricants up to temp (that only come on when it's well below zero out.)

    You can definitely heat low-load houses with mini-splits in Antigo WI. According to data sets (!dashboard;q=Antigo%20wi ) your mean mid-winter temps are even in positive double-digits at about +13F in January , +15F for February which means you'd get a seasonal average COP of about 2.7-2.9or so with a latest-greatest Mitsubishi FH series. That's at least 9200 BTU/kwh, or 109 kwh/MMBTU. At 27 cents kwh that's $29/MMBTU, not exactly cheap, but it beats propane or heating oil in most markets (comparable to heating oil at this year's lower prices, cheaper than the 5-year average price for heating oil.)

    The utilities in WI are among the most backward-looking in the US, and seem to have the state regulators snowed. Wisconsin earned special mention this year from the Green Tech Media policy wonks as among the biggest losers, even mentioning by name the concessions to WE Energies:

    This can change, however, and will (eventually). At 27 cents/kwh it will be financially rational to unplug from the grid with PV + storage solutions within ten years, at the anticipated decrease in cost of those systems by then. If WEPCO finds net-metering too much competition for their crappy "business as usual" business model, they haven't seen ANYTHING as financially damaging to them as outright grid-defection.

    This is already beginning to happen in Australia, where typical residential retail rates are 30-35 cents, where the miserly net-metering arrangement is for the utility to pay 0-8 cents/kwh for the instantaneous power being put onto the grid rather than "running the meter backward" the way it is usually done in the US. That kind of arbitrage buys a lot in batteries and controls, even for those who don't have enough PV to go completely off grid. It doesn't take outright grid defection for more PV & storage to cut into utility revenues. Behind the meter storage was approved in California for PV operators, over strenuous arguments from the utilities. It can happen in Wisconsin too.

    BTW: Have you had any reliability or performance issues with the AirTap? (It's hard to find intelligent nuanced reviews on heat pump water heaters.)

  85. PAUL KUENN | | #87

    Thanks for the update info Dana!

    I asked for clarification from those that said they had "mini splits" but turns out they had the outdoor air to air heat pumps. That would make sense now. I appreciate the clarification. There are only about 3 other houses within 100 miles other than mine that a mini split would work in. Unfortunately, there are only two builders out of about 300 that know how to build a Pretty Good House in NE Wisconsin. On evening walks and local get-aways, I walk through every new construction and see only old methods used. Six to eight studs in a corner or above windows and doors... such waste

    Our AirTap is now 5 years old and has performed well. At first I pushed it to heat the two big floor heating tanks and when the coils frosted up, I had to add their heating coil which melted some internal plastic. Then when moving it to the DHW tank, the copper tubing broke (might have been hung up on the internal copper loop?). Believe it or not, after two calls they replaced the unit free of charge. Now that's service. That might have been because they were new and they knew I gave lots of lectures. Anyways, I have it timed to go on during late hours to avoid the highest KW prices and it heats our water from 90F to 125F in about one hour. I use the condenser water to clean my salty bike off each night:).

    It hurts to know that we always get a "D" for solar in the homeland of the MREA. I'd love Walker to burn his hands touching my solar thermal tubing... just say'n!

    As I've mentioned before, solar does work and I love our thermal set-up. We pay about $165 to WE Energies for the whole year. Get back about $175 on solar credit from February to October. Proof is in the pudding. I'd like more PV but they keep decreasing solar payback and upping "line usage" rates.

    Happy Solstice everyone and thanks for such good information! PK

Log in or create an account to post an answer.


Recent Questions and Replies

  • |
  • |
  • |
  • |