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Community and Q&A

What heating system should I install in my 150-year-old house in Connecticut? Oil boiler, ductless minisplit, or something else?

OpusC | Posted in Mechanicals on

My family lives in a 2-story 2000-sq.ft. balloon-framed house in Western Connecticut (zone 5A). We currently heat exclusively with a Harman XXV pellet stove, which surprisingly keeps most of our house pretty comfortable even in the depths of our cold New England winters. Of course there are some rooms that will get down below 60 on the coldest of nights, but that just means we stay in the warm parts of the house, which works fine for us. We used to heat with a Burnham RS-111 oil-fired boiler piped through about a dozen beautiful and massive cast-iron radiators. We noticed some degradation in the old clay tiles in our chimney a couple of years ago, so we tried heating just with our pellet stove for the rest of that winter and it worked. We’re entering our 3rd winter of using just the pellet stove. We do miss the nice even heat of the old radiators–not to mention the fact that they heated all of our rooms equally–but we don’t miss the high oil bills.

I’ve done a pretty good job of insulating and air-sealing the semi-finished attic. There’s a combination of double-stud walls, rigid foam, air-tight drywall, and cellulose that brings it up to around an R-40. The walls of the house are true 2×4 with blown-in fiberglass of unknown quality from the previous owner. I’ve still got a few uninsulated shed-roof bump-outs to deal with, and I’d like to address the junction between the first and second floor (I’m pretty sure that I’ve got air movement through the siding into the balloon-framed floor system), but there’s not a whole lot more I can do without taking off all of the siding, which is too big of a job for me to tackle myself or pay someone else to do, so I want to focus on the heating system.

So here’s where we’re at:
– We feel like we should install a more-conventional heating system for future resale value, for supplemental heat, and for when we go away for vacations (so we don’t have to ask our neighbors to tend the pellet stove)
– Even though our old Burnham boiler is in OK shape, the chimney would have to be relined in order to use a boiler, but the liner would bring our flue below the 8-in. diameter required by the boiler, so we can’t use the existing boiler with our existing chimney
– I don’t think I want to install a power vent, which might be one option for using the current boiler
– My wife believes that we should install a new oil boiler (which would mean that we would have to put a 6″ SS liner in our existing chimney) because she thinks that prospective home buyers of an old Victorian house would be more familiar with and accepting of a hydronic heating system that uses the old radiators
– I don’t see us using the oil boiler (either the old one or a new one) very often, so I have maintenance concerns with having a mostly idle boiler
– A gas boiler is not an option–there is no gas piped into our town
– I’m leaning towards installing a multi-head high-performance minisplit heat-pump system
– Another alternative would be to install a pellet boiler, but that seems perhaps too exotic and expensive for our traditional old home
– Honestly, we don’t use AC much in the summer, so the added benefit of the AC with the heat-pump option has not been enough to definitively sell my wife on that option
– We hope to move to a new home within the next 5 years, so we’re not looking to invest a ton of money into a new system, but we do want to get something that will work well and be accepted by future home buyers when it’s time for us to move on

What do you all think would be my best option?

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  1. srenia | | #1

    I agree with your wife according to your circumstances. Replacing the boiler makes the most sense in the light you are moving as well. The future buyer heating needs are not going to be the same as yours. The old boiler can drive your resale value down as well. Replacing it makes the home more complete to a buyer.

    1.). If truly you want to save energy loop your water heating through the pellet stove and or new boiler. This would save more money in the short and long term verses a mini split.

    2.). Put new zone controls on the old radiators. Evens the heating out especially when new air sealing and insulation has been done.

    Mini splits are too small, too expensive and break down a lot - lots of maintenance.

  2. Richard Beyer | | #2

    I second that, your wife is right. Boy do we hate hearing that! ;)

    Another option is to install a power vent providing one is available for your boiler size. Your next option is to fix the chimney which can be done providing the degradation is not that severe. If it is to bad to repair it should not be lined for starters. Good masons (which there are many in your area) can fix any chimney problem. Just remember plumber's are not masons and masons are not brick layers so you need the advice from both before you proceed.

    Unfortunately to many contractors are lazy parts changers and masters of everything. Most are either not experienced in old buildings or simply are not interested in tuning in your old system. It's simple economics. It's more profitable to a tradesman to replace and take the easy road out than it is to diagnose and fix the real trouble. Take your time and seek out a good tradesman who will help guide you in the proper direction for your real circumstances.

  3. iLikeDirt | | #3

    This may be kinda out there, but how about replacing the oil boiler with a heat pump boiler? You wouldn't have to touch the the chimney and it would certainly be cheaper to run than anything that burns oil.

  4. gusfhb | | #4

    do you have gas in the street?

    It is pretty hard[read expensive] to make oil efficient. I did it with a Buderus condensing boiler, but I have no gas in the street. A new condensing gas boiler will be cheaper and not need the chimney[although neither does the buderus]

    If the boiler is not on its way out go for mini splits, as adding AC will probably increase resale more than a shiny boiler will.

  5. Richard Beyer | | #5

    Interesting gas is thought to be more efficient in an old home. I was once told this years ago and also considered switching over to gas from oil. A friend of mine installs these systems every day. A lesson learned was if your home is not a tight energy efficient model gas is not efficient, because oil burns hotter (btu's) and can get the water up to temperature faster when the demand is needed. Turned out after careful consideration, dollar for dollar gas would cost more. Today it's proving to cost more for other reasons as shown below. The sad part is as we try to save, which we did find ways, the utility companies refuse to lose. Up go the rates we pay!

    "Massachusetts consumers will pay significantly higher electric bills this winter as a persistent shortage of natural gas for generating plants drives power prices to record levels."

    "The cost for a typical household could top $150 a month, based on an announcement this week from one of the state’s two dominant utilities, National Grid. It said its rates will increase by a whopping 37 percent over last winter’s, solely because the cost of buying electricity from power plants has soared to the highest level in decades, according to a company spokesman."

    "The price shock is driven by New England’s increasing reliance on natural gas as a source for both heating homes and making electricity. The pipelines that ship natural gas into New England do not have enough capacity to meet the increased demand, and during winter, electric plants often end up paying much more for the fuel."

  6. kevin_in_denver | | #6

    I don't remember seeing anything called a "heat pump boiler" before. But sure enough, there is one now: "The NorAire air source heat pump boiler has been designed and optimized to be used for hydronic heating systems. Think of it as a boiler with an overall annual efficiency of 210%"

  7. GBA Editor
    Martin Holladay | | #7

    If you are planning to move within 5 years, I think the simplest thing to do is to line your existing chimney and to install a new oil-fired boiler that is compatible with your lined chimney.

  8. OpusC | | #8

    Thanks, everyone, for the thoughtful and detailed responses.

    Martin, after considering all of the variables and concerns, I've come to the same conclusion that you have: a chimney liner and a new oil-fired boiler will probably match my existing conditions and my long-term plans the best, even if the boiler itself isn't the most efficient heat source on the market. I guess I need to take my wife's evaluation of these scenarios more seriously. :)

    I'll save the high-tech HVAC plans for our next house, which will hopefully be an open-plan, super-insulated ranch house with a walk-out basement.

  9. gusfhb | | #9

    re: Richard Beyer

    the oil vs gas is simply errr, sillyness. You would have to provide some backup for the wild assumptions about gas costing more, it simply does not happen. Add that to the much higher cost of oil equipment and I have no idea where you are coming from

    Gas continues to be cheaper than oil, and the electric rates are not the point here.

  10. user-2890856 | | #10

    Math :

    50,000 x 24 x 5750(hdd) x .605 (cf)
    ____________________________ = 809 gallons oil
    .87(afue) x 140,000 x 70 (dtd)

    Same house with NG

    50,000 x 24 x 5750 x .605
    _____________________ = 1,175 therms NG
    .87 x 100,000 x 70

    Now start your debate ! Here where I live this equates to : Oil 2,410.00
    Gas 1,042 .00

    Remember Keith , this man does not have the option of gas though . You still bring up a good point though with the oil vs gas . Maybe you should start another discussion .

  11. Richard Beyer | | #11

    Good choice Rob.
    Guy's your math may be accurate and the gas guy I know may have his head in his rump according to you, but gas, oil, coal, solar and the hot air we all blow comes with a cost which is not a fixed price. Gas is rising so no matter what you want to debate over here I see gas going much higher than oil this season. The writing is already on the wall. Republicans have taken control so the "pipeline" has become center page again. This issue will not be limited to just Massachusetts. Unlike Martin who lives off grid, we all suffer the consequences of rising electric rates and fuel.

    “Limited natural gas transportation infrastructure ... has led to extremely high electricity prices in the Northeast U.S., and threatens the reliability of the region’s electric grid,” Tennessee Gas reported last month in its request to the Federal Energy Regulatory Commission for the pipeline across Massachusetts. “As a result of the fact that current natural gas transportation infrastructure is inadequate to meet the growing demand in the New England region, gas prices in New England are the highest in the United States.”

    "Supply troubles foreshadow the kinds of ramifications Americans could face if natural gas exports get accelerated or the oil export ban is lifted."
    "U.S. Propane Shortage Provides Lessons For Debate Over Oil and Gas Exports "

  12. user-2890856 | | #12

    Since oil is now being offered at a lower price to counter the moves that Russia and China are attempting I doubt that there will be much movement in any of it this year Richard . Propane will not skyrocket as it did last year , oil will be lower , Ng will be stable , electric will remain about the same . .
    I do however think it is time to start a real effort in educating people on how site derived energyu is the only real way to avoid being completely screwed as this energy game and people's lack of knowledge of how it really works is is exploited . You see , oil does not go up in price folks . Oil is traded in US dollars and when oil prices increase for the most part it is for the simple fact that it takes more US dollars to purchase the same amount of oil . Think I am hallucinating , check out this chart , see oil is still on the gold standard and the US dollar is almost toast as the worlds reserve currency .
    What needs to be done to me is clear , but I'm just a guy who knows how to move energy around and store it . i also know how to make Martin's PV Panels perform better and capture more juice than they do at present and as a by product of that process we can also make heat which we can then use to feed heat pumps more BTUs . We don't really need any of this theft that goes on . However that is a long way off so in the meantime why don't we all do the mot economically feasible thing for each of us . Look for advice from those who know but know how to pick through the nonsense . I will not be sucked into a political debate because all anyone knows about politics for the most part is whta the people on TV told you .

  13. Expert Member
    Dana Dorsett | | #13

    Replacing a functioning boiler that you don't intend to use except as back-up would be a waste of money. A retrofit stainless flue liner is probably the cheapest and "right" thing to do here.

    Selecting & installing heating equipment for the next owners is just plain silly. As long as the boiler works you can still sell the place, and buying a brand new oil boiler would not increase the sale price appreciably.

    The notion that oil is going to be cheaper than natural gas any time soon is a dubious proposition at best. The per-MMBTU delta my be narrowing now that crude pricing has dropped, but even if gas rised to $1.50/therm it would take $2/gallon oil to compete with it for space heating. Retail wintertime natural gas pricing hasn't been that high in New England in more than 7 years, but #2 heating oil hasn't been than cheap in more than a decade. At recent years' pricing oil has been more than 2x the cost of natural gas. This year it may be only 1.8x as expensive- not exactly "party time". At the current $3/gallon price point this week it would take an unprecedented natural gas price of $2/therm to be at parity.

    The prices are somewhat linked, but high crude oil pricing has been driving the cost of natural gas lower. As oil prices drop, there will be slow rise in the price of natural gas, but it will take at least three years of very low crude pricing before we could see $/MMBTU parity between retail #2 oil & natural gas.

    This is because the US gas-glut is a partly a function of the price of crude oil. "Dry" gas wells in shale or coal seams cannot be extracted at a profit at recent years' pricing, but those with high liquids fractions can, since the tight-oil & propane etc fetch a higher price. Once a well is fracked and producing it takes only about 3 years before it has produced 95% of all the liquids it ever will. Now that crude oil pricing is down due to economic slow down in Europe much of that tight oil is no longer profitable, which means the drilling rates have slowed down. Both shale gas and shale oil production will be falling off it that continues for three years, and the price of BOTH will rise, even if demand growth is flat or even negative.

    As soon as world oil demand picks up driving the price of oil higher, the price of the natural-gas in the US will fall again as the "drill baby drill" crowd picks up the drilling rate once again. Only when oil demand falls off permanently will the price of natural gas in the US fall to a "natural" level more closely related to the cost of extracting it. Right now and into the intermediate future, it's being "subsidized" by the liquids-fractions. Coal seam methane is still be profitable at prices well below what it takes to support dry shale gas production on gas revenues alone, but it takes more than the $2-4/MMBTU recent-years' pricing to keep developing coal seam resources and bringing them online.

    The ISO-NE gas- grid capacity issue has been a bit overwrought, but the spot price of gas can locally hit north of $100 /MMBTU (25-50 times the spot-market price at the Henry Hub) when that happens, and that's what occurred last winter, which is why the 6-month generating contracts are over-the moon high, doubling the wholesale price of electricity charged to the New England utilities. If you add up all of the hours that the gas grid was maxed out it only comes to 40 hours, and not more than a handful of hours at any given stretch. We're talking fewer than 1% of the hours in a heating season, but a much larger fraction of the fuel cost to generators. Unlike the power generators, local gas distribution grids are financially sheltered from those spot market spikes by longer term contract pricing. Under the regulatory decoupling most wholesale electricity contracts with generators are on a short term basis, and the generators are NOT able to fully protect themselves from the spot market. But local gas storage is one possible solution for them (and by extension, the electricity ratepayers.)

    At the ~25 cent retail price of electricity wrought by this situation all sorts of efficiency measures become no-brainer type investments. Those heating with resistance electricity can buy a mini-split, which would pay for itself in 2 seasons at 25 cents/kwh. But that would also reduce total electricity use, conserving gas-storage reserves. Electricity demand has been flat to falling in the ISO-NE region for about a decade now, and an electricity price hike will just further reduce demand in structural sorts of ways that last well beyond the winter season. If FERC Order 745 hadn't been shot down in the D.C. District court last summer, aggregators could have gotten capacity payments to be able to retain the ability to simply turn stuff off during demand peaks, which would reduce the gas-grid capacity issues that affected the gas-fired power generators, now that the limits are well understood, but alas, that "cure" going to have to wait for the legal appeals process to work out. In the meantime there is still exposure to those conditions should another Polar Vortex situation occur. But this is a reasonable cheaply solved problem.

    But this year it's pretty exciting stuff- National Grid's MA operation just had a 37% price hike, and N-Star's MA region has just requested a 30% price hike, all due to gas-fired power generating companies hedging their downside and recovering losses from last year in the new winter-term contract. As natural gas is the fuel behind something like 50% of the grid supply in New England, the gas grid tail wags the electric grid dog in ways that hadn't been seen until recently. But that is only a temporary condition, and has nothing to do with the market fundamentals around natural gas or electricity nationwide.

    The long term trend on electricity pricing is still downward, driven in part by the low & ever-falling lifecycle cost of wind & solar. Onshore wind hit lifecycle cost parity with $5/MMBU combined cycle gas awhile ago, and as gas prices rise, wind will steal an ever larger share of that market. Distributed PV in 2014 is cheaper than gas-fired peaker plants even at low spot-market gas pricing, and will be cheaper than $5/MMBTU gas in combined cycle plants in less than 10 years. Electricity price volatility in the near term will accelerate the rate at which newer-cheaper stuff gets built. It doesn't take a whole lot of "other" to over the gas-grid capacity limits that only get hit 1% of the heating season, but until it gets built, seasonal electricity price volatility can be expected in the ISO-NE region. But since that other zero marginal cost generation stuff is still operational the other 99% of the time it will eat into gas fired generators' capacity factors, and conserve any gas-grid storage that is in place. Electricity price volatility simply cannot go on for years- the market will take care of it.

  14. GBA Editor
    Martin Holladay | | #14

    Rob told us that "the chimney would have to be relined in order to use a boiler, but the liner would bring our flue below the 8-in. diameter required by the boiler, so we can't use the existing boiler with our existing chimney."

    You tell Rob that "a retrofit stainless flue liner is probably the cheapest and right thing to do here."
    OK -- we agree on that.

    You also said, "Replacing a functioning boiler that you don't intend to use except as back-up would be a waste of money." But once Rob lines his existing chimney, he can't use his existing boiler. So what do you suggest that Rob should do?

  15. OpusC | | #15

    Thanks for pointing out the concern about the flue size, Martin.

    And I would probably use the boiler for more than backup, if for nothing more than to keep the distant corners of my house warmer--including my kitchen which is far enough from the pellet stove that it stays on the cool side in the dead of winter. My house has a few zones already and we had run the boiler and pellet stove in unison a few years ago which kept our oil consumption at around 100 gallons per year and pellets at 3 tons. Now we're using about 4-1/2 tons per winter while just running the pellet stove. If we got a better boiler than our old one, I think we could run the two heating appliances in unison again, have a more comfortable house, and only spend a couple hundred extra dollars per year on fuel. That sounds like a good deal to me, even if it's not the perfect HVAC solution.

    Plus I still have a few insulation and air-sealing projects to do, so in the end I might not be spending any more per year on heat than I do now.

  16. user-2890856 | | #16

    Rob, Could you tell us how over radiated the house is and the heat loss ? Is the installed radiation so much that lower water temps could be used ?

  17. Richard Beyer | | #17

    Rob said; "If we got a better boiler than our old one, I think we could run the two heating appliances in unison again, have a more comfortable house, and only spend a couple hundred extra dollars per year on fuel. That sounds like a good deal to me, even if it's not the perfect HVAC solution."

    Hypothetically speaking, if a new oil (stainless liner) or gas (aluminum liner) system cost @ $7500.00+/- installed, the break even point before selling the home does not make much sense to me if your planning to spend on top of this an additional $200.00 per year. It makes more sense to install air sealing techniques with this money which will give you instant savings and a more comfortable home by doing so.

    I would start by requesting a energy audit from your local utility company first. This can be had for a minimal cost. After your air sealing issues are complete only then is it time to size the house for the appropriate sized furnace based off of the final blower door test. Otherwise your simply wasting money for an over-sized unit. Just my opinion.

    Martin said; "But once Rob lines his existing chimney, he can't use his existing boiler. So what do you suggest that Rob should do?"

    I suggest that Rob install a power vent in lieu of lining the chimney if one is available for his existing unit if he does not air seal his home. The cost difference outweighs any real benefit that the existing chimney provides. Most plumbers prefer power vents around here with new units and most all new homes have power vents over flue style exhaust.

  18. OpusC | | #18

    Richard McGrath,
    I know I did heat-loss and radiator calculations a while back--I'll have to see if I can track down my notes or I'll just redo them and get back to you. Are you thinking of suggesting something like a water heater to feed the radiators if there are enough of them and I get the house tight enough?

    Richard Beyer,
    I do plan to get an audit and do some more insulation and air-sealing. I don't anticipate getting the boiler before that is all done either. I'm pretty sure my existing boiler will be oversized once I'm done, but I'll have to run the numbers to know for sure.
    If I could make a power vent work, I'd be glad to consider it. It would certainly be cheaper than a new boiler. My issue is that the sill on my house is a massive beam sitting on top of old brick that is only about 8 inches above grade. I may be wrong, but to have enough clearance for a power vent I may have to go above the floor to clear the beam and get high enough that I clear the snow in the winter. That is unless it's possible to go through the beam or the brick and route the vent higher once it's outside the house. Going above the floor may be an option too though, because there is a built-in bookcase on the outside wall in one room that I may be able to box in to hide the vent. Any thoughts on this?

  19. Richard Beyer | | #19


    Elevations are crucial to code compliance. The minimum height restrictions are provided by the power vent manufacturer and code enforcement. Like I previously said, it's a good option if one is available for your boiler.

    I included a schematic from a power vent manufacturer which allows for a 12 inch soil to vent clearance below. This vent may be to small for your boiler though.
    Another option may be to build a false window well to allow for additional clearance when soil elevations are as low as yours. I would consult with your code official to make sure this is allowed in your area. I have seen it done in New Hampshire where they get an abundance of snow.

    What ever your choice, I suggest for you to consult with a power vent manufacturer before finalizing your decision. Best of Luck

  20. OpusC | | #20

    Hey everyone, I'm taking a second pass at this scenario, as I haven't done anything to address it since this thread was started, several years have passed, and now we plan to stay in our house a lot longer.

    Here's where I'm at:
    - we expect to be in our house for at least another 8-10 years
    - it's a 2500sq.ft balloon framed 1870s house with blown in fiberglass in the walls (but no sheathing under the siding, so not great for air-sealing), a well insulated attic, a stone basement, decent but not great vinyl replacement windows, and quite a bit of air-sealing already done in the rest of the house
    - I need to either get a new boiler and a stainless liner for our old chimney, OR get a power vent to make our 30-year-old cheap steel boiler usable ( though I'm not sure how much life is left in that boiler), OR start from scratch with something else, such as minisplits
    - I have a good indoor oil tank, and some nice old cast-iron radiators in every room
    - my old brick chimney definitely needs lining, and could probably accommodate a 5 or 6 inch stainless liner
    - we don't have natural gas as an option
    - our electric rates in Connecticut are pretty high, but I would consider looking into solar if people think switching to mini-splits is a good idea

    Thanks for your help!

    -- Rob Wotzak

  21. GBA Editor
    Martin Holladay | | #21

    Welcome back to the Q&A pages of GBA.

    Clearly, a few things have changed since you posted. Instead of your plan to move away in 2019, you are now planning to stay in your house until 2025 or 2027.

    That changes my advice. I'd lean towards the installation on a few ductless minisplits.

    I'm curious: since it sounds like you haven't installed a liner for your chimney yet, how have you been heating your house over the last 3 years? Have you been venting your boiler into the unlined chimney?

  22. Expert Member
    Dana Dorsett | | #22

    Martin- the second sentence of the original post reads:

    "We currently heat exclusively with a Harman XXV pellet stove, which surprisingly keeps most of our house pretty comfortable even in the depths of our cold New England winters."

    Now that the houses is tightened up and insulated, all but the smallest new oil boilers are likely to be 2x oversized for the design heat load, but it might be less expensive to install (and operate, at current CT electricity rates and oil pricing) than a few mini-splits.

    If the existing boiler is suitable for retrofitting a power vent, that may be the "right" thing to do from a financial point of view. Back when #2 oil was $4-5/gallon heating with the pellet stove or mini-splits was a HUGE amount cheaper, but now that it's in the $2.75 /gallon range that's no longer the case. CT has some of the highest electricity pricing in New England, currently running about 21 cents/kwh.

    The steady state efficiency of the oil-burner is probably about 85%, but the oversizing factor and idling/distribution losses probably brings that down to an as-use 75% AFUE.

    So at 75% efficiency a gallon of oil at 138,000 BTU/gallon delivers about 100,000 BTU/gallon as heat into the house, or 10 gallons per million BTU (MMTU) At $2.75/gallon that costs $27.50/MMBTU.

    A pretty-good name-brand cold climate mini-split will run an HSPF of about 12 BTU/watt-hour, or 12,000 BTU/kwh. So it takes (1,000,000/12,000=) 83 kwh per MMBTU. At 21 cents/kwh you're looking at about $17.50/MMBTU.

    That's still about a 35% discount from burning oil, but a far cry from what it was during the recent high-price oil era, and not a financial no-brainer in a 10 year analysis when considering the very substantial difference in up-front cost between power-venting the existing boiler vs. $10-15K for a bunch of mini-splits. From a resale point of view the mini-splits may or may not cut it from a code-compliance perspective, since all occupied rooms need to be capable of automatically/thermostatically heating it to 68F at the 99% outside design temperature. If there's a radiator in most or all rooms, the boiler system is probably compliant.

    But the boiler can't air condition or dehumidify, and the mini-splits can. It may be "worth it" to install one or two mini-splits for the luxury of air conditioning an as a greener way of heating than pellets or oil, while keeping the oil-fired system functional, even if you never use it. An oil-boiler that is essentially off all the time except for once per year testing prior to the heating season will easily go another decade or two, and you'd have a code compliant central heating system when it's time to sell.

    An new pretty-good smallest of the line 3 plate oil boiler + stainless liner to replace the existing oversized beast would run $5-8K in my neighborhood. A 1.25 ton cold climate mini-split is less than $5K and probably covers more than half your design heat load. If the beastie can be retrofitted as a power vent for a couple grand you could STILL buy at least one decent mini-split that would heat almost as well as your pellet stove.

    I'm a bit concerned about the blown fiberglass in unsheathed walls, with the siding nailed directly to the studs. When the stud bays were empty the siding had a great drying channel to dry into, but when full of fiberglass it doesn't. The fiberglass will wick some moisture off the back side of the siding, but it's less than ideal. This is often a recipe for causing the siding (or at least the paint) to fail. It'll be most problematic on the north side, where it doesn't get the heating/drying benefit of direct sun. If any of the siding begins to show signs of getting punky you may be in for installing sheathing + new siding, which isn't a cheap proposition.

  23. GBA Editor
    Rob Wotzak | | #23

    Thanks Dana, that's a lot of info to process, but I think I'm able to get the gist of what you're saying. Honestly, if I take any route other than the power vent I'll have to finance the project, and I'm a little wary of maxing out my current budget with a loan. I've worked as a remodeling contractor in the past, and with my skills I'm comfortable doing just about everything except commissioning/tuning a new system myself (whether it be a boiler or mini splits), so I'm open to creative solutions. Again, I'm happy to keep using my pellet stove to provide much if not all of my heat, but I'm uncomfortable with the lack of an automatic heating system that would allow us to leave the house for days at a time. If I do commit to financing a new heating system, my main concern is finding a heating contractor that has the know-how and integrity to sell me a system that matches my needs. I had a local guy in here this week who wanted to sell me a 100K btu Peerless cast iron boiler, and said he doesn't have one smaller to offer me. If anyone can point me in the right direction to perhaps even find a consultant who can spec a system for me, I know of some good individual contractors who could help me put the system in. Thanks again for your advice.

  24. GBA Editor
    Rob Wotzak | | #24

    Martin, I just wanted to let you know that I never used the chimney once I realized it was bad. I've been exclusively heating with my pellet stove since my original boiler died. I definitely like the idea of getting some mini splits, but my wife's still not convinced--and I do miss the nice even heat of our old cast iron radiators. My house was so much quieter and less dusty when we had a hydronic heating system.

  25. GBA Editor
    Martin Holladay | | #25

    Sorry I missed the reference to the pellet stove. I'm glad to hear that you haven't been using a defective chimney.

    If you want to hire a consultant to help you design a heating system, the consultant doesn't have to live near your home. For some suggestions, see this article: Who Can Perform My Load Calculations?

    (Although much of the article is focused on load calculations, it also delves into the issue of heating system design.)

    One more point to bring up when you and your wife discuss heating equipment options: Just because your house is dusty and noisy when heated by a pellet stove, doesn't mean that ductless minisplits will be dusty and noisy. I suspect that you will find that ductless minisplits are considerably quieter and less dusty than a pellet stove.

  26. Expert Member
    Dana Dorsett | | #26

    "Even though our old Burnham boiler is in OK shape..."

    "...since my original boiler died."

    Is the boiler itself now dead, or is it just the chimney/venting that's the problem?

    If it's less than a couple grand to retrofit a direct-vent approach to the "OK shape" Burnham it's probably going to be "worth it" to eventually do that, even if you heat primarily with a pellet stove or a mini-split. Even though it's almost certain to be ridiculously oversized the burner can probably be down-fired using a smaller nozzle, which will inevitably lower it's steady state efficiency, but improve it's as-used AFUE. (The smallest legitimate nozzle is probably specified in the manual for the thing, which is probably available online.)

    Martin has it right that a mini-split will be much quieter than most pellet stoves. Most good ones are quieter than a refrigerator except when running at maximum speed.

    Energize Connecticut offers a $500 rebate subsidy (per house) for mini-splits, which would surely take some of the sting out of a mini-split installation:

    For purposes of guesstimating a mini-split size (assuming you still want at least one mini-split, using it pretty much like your pellet stove), how much pellet fuel do you use in a typical season, what is your ZIP code (for weather & design temp data), and what is the nameplate efficiency (or model name/number) of your pellet stove?

  27. GBA Editor
    Rob Wotzak | | #27

    Dana, the original Burnham RS-111 boiler died, but someone gave me the same boiler in much nicer condition. Once I removed the old boiler to install the new one (should have been an easy task because the connections were identical), I noticed the problems with the chimney.

    My house has vinyl siding from the 80s over that silly thin EPS/foil underlayment, which is over the original clapboard siding. I've done variations on cut-and-cobble (spray-can foam and XPS) in the entire attic and in a few main-floor rooms that I renovated over the years. I also added cellulose inboard of the foam in the semi-finished attic where I did some double-stud framing with air-tight drywall. The house is just too tall and my budget too small to tackle a large-scale insulation upgrade right now. I might consider one day pulling the siding and doing some upgrades from the outside. If only I had bought a ranch house instead of a 40-foot-tall Victorian. :(

    We've used anywhere from 3.5 to 4.5 tons of pellets per year.

    My zipcode id 06776 (New Milford, CT).

    We're running a Harman XXV pellet stove which has a max output of 50,000 BTU. It's a nice stove with thermostatic control and an auto-ignition feature, so it will turn itself off on a sunny winter day if our sunroom pumps enough heat into the house, and light back up when the house cools off.

    Thanks again to you and Martin for all of your advice!

  28. Expert Member
    Dana Dorsett | | #28

    Using Danbury's weather data your climate is good for about 6200 heating degree-days per year. Your 99% outside design temperature is probably in positive low single digits F (Waterbury's is +2F), but for yuks let's use 0F as a design temperature, and 65F (the degree-day base) is the presumptive heating/cooling balance point. So for linear approximation purposes you have 65F heating degrees.

    The DOE presumes a thermal efficiency of a generic pellet stove is 78%, reality is probably more like 65% when operated outside of a test lab, but for estimation purposes let's use 70%.

    A ton of dry pellets has a source fuel content of ~16,500,000 BTU/ton, and you use ~4 tons/year, or about 66,000,000 BTU/year input. The heat that ends up in the house at 70% efficiency is then 0.7 x 66,000,000 BTU= 46,200,000 BTU.

    So per HDD that's 46,200,000 BTU / 6200 HDD= 7451 BTU/HDD. With 24 hours in a heating day that becomes an average output of 7451 / 24= 310 BTU per degree-hour.

    With 65 heating degrees that's an implied as-used heat load of 65F x 310 BTU/F-hr= 20,150 BTU/hr delivered into the same room as the pellet stove. (If the whole house were able to stay at 70F when it's 0F out it's probably more like 2x that much.) That's also probably less than half of the rated BTU output of your pellet stove.

    To do that with a single mini-split head takes a cold-climate 1.25-1.5 tonner, such as Mitsubishi's FH18NA, or Fujitsu's 15RLS3H:

    To keep rooms remote from the mini-split head heated to 70F would require doing a Manual-J load calculation on those rooms to get the sizing right, but for a single head located in the same room as the pellet stove either of the above units would be able to heat that space, but the amount of convective heat transfer to the other rooms will probably be less, since the air coming out of the mini-split will be maybe 110F, not the 250F+ column of air rising off the stove. It'll still do a lot for the upstairs rooms (assuming an open stairwell), but it'll be different, and it may well be worth adding another up stairs if it doesn't quite cut it.

    As far is down-firing the RS 111...

    I wasn't able to find the full manual of the RS 111 online, but the burner nozzle spec for that unit is a 1.1 gph version, so it's BTU/hr output rate is likely to be on the order of 125,000 BTU/hr, give or take a little (depending on the tuned as-used combustion efficiency.) The RS 109 was essentially the same boiler jetted with a 0.85 gph nozzle good for 98-100,000 BTU/hr of output. I suspect that if power-vented you could down-fire the RS111 to 0.85 gph or even 0.75gph without much problem, whereas if chimney-vented stack condensation would be a problem unless detuned to 75-78% or so. Clipped from the Beckett burner guide:


    RS109 AF........................F3 3-1/2” ...0.85 X 80°A — AF60ZP 100 B3001 S-6 / B-0 3”

    RS110 AF........................F3 3-1/2” ...0.90 X 80°A — AF60ZP 100 B3001 S-6 / B-0 3”

    RS111, RSM126 AF........F6 3-1/2” ...1.10 X 80°A — AF60ZG 100


    RS-111 is probably fairly similar (but not identical to) the RSA 110 (which has a DOE output of 128K, an IBR output of 111K ) or RSAH 110 (DOE output of 119K).

    In that series the water volume of the (0.75gph) RSA 85 is 8.5 gallons, to the (1.1gph) RSA 110's 9.1 gallons and are , which is less than 10% difference. If the RS series is similar, dropping in a 0.75 X 80°A nozzle and tuning it to the highest combustion efficiency it can deliver (probably 80-82%) shouldn't be a problem. That would deliver 80-85,000 BTU/hr of DOE output, which should be enough to keep the whole place toasty even well into negative double-digits F, with an oversizing factor of more than 2x but still less than 3x for the actual whole-house heat load @ 0F indoors / 70F indoors (everywhere) .

    If / when the power venting is installed and tuning it up, have the discussion with the burner tech and suggest a 0.75 X 80°A nozzle rather than whatever is currently installed- see if they have any issues with going that low. It's doubtful that you'd want to go any lower than that, given that it's a 32% reduction in burner size. If dropping that low keep eye on the return water temperature (with the system fully up to temp) entering the boiler- if it's 135F or less it could be susceptible to condensation on the heat exchanger plates, which would require some adjustments in the near-boiler plumbing. It's likely that it already has a system bypass or boiler bypass plumbed-in, a common method of limiting boiler condensation in oil boilers serving high mass radiation. There is usually a ball-valve on the branch for adjusting the flow to keep the entering water at the boiler at a higher temperature, and it would likely need to be adjusted if the boiler is now putting out 30-35% less heat. When the system is already heated up, tweaking the flow to where the return water is above 140F would be about right. (It'll be a bit lower temp during a warm-up ramp.)

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