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Converting from oil heat & electric hot water to geothermal and redesigning utility room and master bath

I am moving from Southern California, where I typically don't heat or cool my home to Central Pennsylvania.

The home I am purchasing has Oil Forced Air Heat and Electric Hot Water and appliances.

There are no Natural Gas Lines near the home - so Natural Gas is not an option.

The home was built in 1949 - Mid Century Modern Ranch home on a slab foundation, no basement. It is a 1784 SF home with 6 rooms - 2 bedrooms, 2 baths, kitchen, Utility room, 2 halls and Living Room. It was a cement block home and someone over the years added dryvit stucco to the outside. Exterior walls end up about a foot thick. The bedrooms and bathrooms have art deco glass block windows. The kitchen has a small window over the sink and a bay window in the breakfast nook area. The livingroom has a bay window and a front door. The master bedroom also has a set of french doors to the back yard. One hall has french door to the front patio and the second hall has a flat window.

The home does have central AC.

Issues -

1. The cost of oil is high and I expect it to rise.
2. The layout of the laundry/pantry/utility room places the hot water heater in the space that is used by the master Bath/ master closet. Would like to move things around, but not sure how.
3. Oven/Stove is electric (I am used to natural gas, but could learn to cook on electric and use the outdoor kitchen/bbq in nice weather)

I am thinking about going geo thermal for heat. I realize that initial investment is high, but don't want to be at the mercy of the oil market prices. The home is on over a 1/2 acre of land so I think geo thermal could be installed.

Thinking about what to do with the water heater - love the space saving of a tankless system, but without natural gas not sure this is a good option.

I don't know how to redesign things without a good idea of how much space will be needed for furnace, electric panel and water heater...

My ideas for redesigning include moving the washer dryer to the garage.

I don't know if it is good to use the same furnace, keep oil as a backup or buy a new one. Could a new one be placed in the garage or is it better left where it is? What are the pros and cons of moving the hot water heater?

it is obvious that the wall separating the master bath and utility room is not original (the glass block window is split by the wall with one row of glass block in the utility room, one row behind the wall and the remainder in the master bath.

I have attached a floorplan. The use of space in the master bath/closet is awkward and pictures of the home before the last purchase shows the shower was where the toilet currently sits and the listing showed that the washer/dryer were in the master bath. Not sure how it was laid out or what other changes were made. The last owner didn't disclose any structural or major renovations, but based on the photos, he did swap the position of the toilet and shower - don't know if it was done to code or permitted or if permits would have been required.

A little scared about what I may find when and if we redesign the master bath/closet, but am sure the space could be more efficiently used, especially if we move or eliminate the water heater.

Looking for advice, ideas, pitfalls that I should be aware of or thought that may change my plans.


Floorplan.jpg215.81 KB
Asked by Jennifer Hogan
Posted Sun, 04/06/2014 - 18:24
Edited Mon, 04/07/2014 - 05:52


12 Answers

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Picute of Utility Room and a couple of the Master Bath

20140223032538445746000000-o.jpg MasterToilet.JPG 20140223032216644147000000-o.jpg
Answered by Jennifer Hogan
Posted Sun, 04/06/2014 - 18:38

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Picture of the master bath before previous owner changed things.

Answered by Jennifer Hogan
Posted Sun, 04/06/2014 - 18:39

Helpful? 1

Hi Jennifer,

I'd actually think your house layout is more suited to heating with ductless mini-split(s) rather than a central ground-source heat pump (or any central forced air heat pump, really).

Here's why a forced-air ground source heat pump may not be ideal in your specific case:

  • The equipment required for a ground source heat pump (air handler + flow center + piping) may require slightly more floor space than your current oil furnace
  • Usually, you'd want a desuperheater to supply hot water during heating and cooling. To do that effectively, you'd need *two* tanks for holding water - one to serve as a buffer tank (which is pre-heated using the desuperheater), and another true hot water tank (fed by the buffer tank). Again, more floor space
  • The ductwork may not be sized correctly for the high-volume, low-temperature air produced by a heat pump. Oil furnaces typically move a smaller amount of hotter air.
  • You're on a slab - are your ducts run above the living space? If so, is the attic part of the conditioned space (i.e. the insulation applied to the roof or roof rafters, rather than above the ceiling)? If the ducts are not in conditioned space, you'll probably need to seal and insulate them, or redo the insulation so that the attic is conditioned space.

If you go the mini-split route, you have a couple different approaches you may take. Some may be able to save you even more critical floor space. For example:

  • You could keep your existing oil furnace, and install a mini-split or two to carry a the bulk of the heating load (at much lower cost). Just set the thermostat for the oil furnace down, and the mini-splits higher. This can take a significant dent out of your oil bill with very little work
  • Install a ductless mini-split or two, take out the oil furnace, and install electric resistance heat in the bedrooms as a rarely-used supplement. This will allow you to use the space taken by the oil furnace for some other purpose!

Your small house and simple floor plan make the ductless mini-split route look attractive. Go for one of the cold-weather units mentioned in one of countless articles on this site.

Lastly, is your garage heated? If not, don't put the washer & dryer there! If so - watch out for rust. Heated garages + road salt in the winter is what kills cars the fastest. You may consider not heating it.

Answered by Aaron Birkland
Posted Sun, 04/06/2014 - 20:13

Helpful? 1

I'd like to echo some of the advice that Aaron gave you. The best way to lower the cost of space heating for someone in your position is to install a few ductless minisplit units. A ground-source heat pump system (sometimes called a geothermal system) costs so much to install that it rarely makes sense for a single-family home.

I don't think that people in central Pennsylvania put a washer and dryer in their garage. That's a southern California approach. As Aaron pointed out, most garages are cold, as they should be -- and that is no place for a washing machine, since the plumbing will freeze.

When it comes to choosing a water heater, there is no simple answer. In some cases, a plain old-fashioned electric-resistance water heater may make the most sense. I recommend the following article: All About Water Heaters.

Answered by Martin Holladay, GBA Advisor
Posted Mon, 04/07/2014 - 06:50

Helpful? 1

You could also consider a central ducted heat-pump system tied
into the existing forced-air ductwork. I can confidently say that
it works a lot better than parts of the industry appear willing
to admit so far, and I think at this point all the major
manufacturers have ducted air handlers available [I know about
Daikin, I'm not 100% sure about Mitsu/Panasonic/Sanyo/LG and/or
the US brands without researching]. But minisplits aren't the
sole answer for heat pump retrofits.


Answered by Hobbit _
Posted Mon, 04/07/2014 - 12:22

Helpful? 0

I really appreciate the answers - as a novice to having to heat a home I didn't know where to start on the research or what could or couldn't be done. Had never heard of a mini-split or the central ducted heat-pump system. Looks like I have more education ahead of me!

As far as the garage, since it is 27'x37' I am thinking of splitting the area into several sections, one for storage, one for laundry, one for a workshop. I will only need 2 parking spaces in the garage. My current 2 car garage is 20x22 so I thought the extra sq footage would be fairly easy to section off.

The garage is not insulated or heated, but thought about adding insulation and minimal heating where I section off the laundry and work space. Thinking that if I place them against the wall that is common with the house there may be enough heat tranfer to safely do this without adding heat, but wasn't sure. Also wasn't sure how to get the water to the garage. There is a sink in the garage on the furthest wall from the house. Not sure why those pipes don't freeze or if I will have to do something to make sure it doesn't freeze.

Does my logic seem reasonable? Anything else I should be considering?

Answered by Jennifer Hogan
Posted Mon, 04/07/2014 - 12:51

Helpful? 1

The existing duct system may not always be suitable for a right-sized ducted heat pump retrofit-only sometimes, and many ducted systems have very limited capacity at central-PA type 99% outside design conditions. That may be a reasonable approach for a way-better-than-code house, but for sub-code R levels CMU house with sub-code windows it could be a problem. The thickness of the Dryvit stucco and the actual location matters. A 4" application of Dryvit (R15) gets you to about code-min for a climate zone -6 (the colder parts of central PA) CMU wall, and is just a hair above code min for zone 5 (most of central PA). See the R value for "mass walls":

It's fairly easy and cheap to buy sufficient capacity (and high efficiency) at cold temps with a mini-split solution, provided the floor plan is sufficiently open. Sizing any heating system correctly requires some analysis of the actual heat load.

Answered by Dana Dorsett
Posted Mon, 04/07/2014 - 13:38

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The location is Lebanon PA (17046 zip code). The home sits at the break between the city and the Amish farmland. It is literally the last home within city limits.

I am researching potential answers myself because most of the tradesman in this area will be Amish. The plus side is that they will be fair and honest and the work will be done right the first time. The negative side is that they don't trust anyhing new. They use horse and buggies for transportation because cars are an unneccessary luxury. They may not consider newer technologies when they offer advice and they may advise against newer technologies based on the culteral tendancies. They also will not be overly concerned with "green". Just not important to them.

Answered by Jennifer Hogan
Posted Mon, 04/07/2014 - 14:05

Helpful? 1

In Lebanon PA you're on the warmer edge of US climate zone 5, and your 99% outside design temp is about +13F. That probably seems cold to a soCal trans-plant, but that's a lot warmer than US zone 6, most of which has design temps in negative digits F.

But +13F is also no hay problema for cold climate mini-splits, or even some that aren't specifically designed to operate well into negative digits F.

A heat pump is basically an air conditioner with valving to allow the direction of heat being moved change directions from pumping heat out of your house to pumping it in. Ground source heat pumps (aka "geothermal" or GSHP ) is just one variation on the theme. Air source heat pumps draw their heat from an outdoor coil in much the same manner that air conditioners dump the excess heat of the house into the outdoor air.

Ductless mini-split heat pumps are basically a non-centralized air source heat pump that only directs it's heat to & from an individual room. With an open floor plan adjacent spaces naturally convect air between them whenever there is a temperature difference between the spaces, limiting that temperature difference, which make "point-source" heating & cooling an acceptable option. The issue then becomes how to deal with spaces that are doored-off from the adjacent spaces. Almost all of the ductless mini-splits that would be appropriate here are "inverter drive", variable-speed modulating systems, somewhat akin to 2-stage central air conditioners, only better, in terms of both comfort & efficiency. They're whisper-quiet compared to traditional ducted AC & heat pumps- most of the time they're idling along between low & mid speed, where they're quieter than your refrigerator. The outdoor units on these systems are similarly quiet- the fans & compressors are variable-speed, and the compressors are scroll-compressor technology that works with a rolling action rather than a reciprocating piston, for very low vibration and noise.

In your climate the better versions will operate at the same or BETTER efficiency of a typical GSHP, but are a fraction of the installed cost, and have very low system design risk compared to GSHP (or ducted systems). They are a well-engineered "system in a can"- the primary factors affecting efficiency and comfort being sizing it correctly for the load, and the outdoor air temperatures. When modulating at part-load the efficiency soars compared to running flat-out, but cycling on/off from being oversized starts to cut into their operational efficiency too.

I sincerely doubt you will find Amish tradesmen designing and installing GSHP systems, and wouldn't necessarily expect optimal system designs even if they did. There is real risk in GSHP systems, and you'd need to vet the contractor EXTREMELY carefully to be sure you get the performance paid for. Even though best-in-class systems would beat mini-splits on efficiency in your climate, most "as installed" real-world systems won't- or a least not by enough to rationalize the huge uptick in cost. Without knowing what your R-values and window-U-factors are it's hard to say with any certainty, but I'd hazard that your heat load a +13F is in the neighborhood of 25,000BTU/hr. If that is the case could probably do just fine with a single 1.25-1.5ton mini-split with the interior head mounted in the living room, and installing a 450-600watt radiant cove heater at the crown molding level in each of the bedrooms, controlled with both an occupancy sensor and line voltage thermostat. A cold-climate mini-split that size would cost $4-4.5K for a total installed cost in my neighborhood, the cove-heaters & controls would run ~$250 in hardware (intallation extra) for each room, but you'd have to work at it to break $7K.

Since a mini-split runs at better than 3x the average efficiency of the radiant coves it's better to "set and forget" the mini-split setpoint to some thing on the warm side to let it cover as much of the heating of the doored-off rooms as possible. If the doored-off bedrooms have individual heat loads of 5000BTU/hr or more (they probably don't, but if...) one could rationalize adding a ductless head for that zone. There are several 2-3 head "multi-split" units out there that could be used, albeit at a slight hit in operating efficiency over a single-head mini-split. By using an occupancy sensor control strategy on the radiant coves you can let those rooms run cool when not occupied. Radiant coves come on within 5-10 seconds, and since they heat the room by heating the OBJECTS in the room directly (including the humans), it's still pretty comfortable as the room is coming up to temperature.

Depending on your actual heat load numbers, a 3-ton Carrier Greenspeed fully modulating ducted system would probably fill the bill at a slightly derated efficiency from ductless, but I'm guessing the upfront cost would be more than 2x the cost of a ductless system. Dumber 1 & 2 speed heat pumps probably could too, but most of those run at about half the efficiency of a mini-split (or a Greenspeed.)

With a spa tub it's not clear how you would even fill the thing with an electric tank hot water heater unless it's a 100 gallons or more (or the world's tiniest spa.) Are you sure the existing HW heater can actually fill that tub?

Answered by Dana Dorsett
Posted Mon, 04/07/2014 - 16:39

Helpful? 0

Thank you for the explainations. This has been extremely helpful. Still in escrow, so I did not actually attempt to fill the spa tub. Never occured to me that the hot water tank wouldn't fill the tub, but we have a home inspection early next week.

What do I do if the water heater is not sufficient to heat the tub - add a flash water heater just for that or is there some other type of booster that could be used? I do love hot bubble baths and the current master only has a shower.

Trying to make sure that I budget money appropriately and don't spend money on a pretty couch when it would be smarter to get a new window or add insulation or upgrade the heating/AC.

I did add an option to the escrow to have a HVAC inspection prior to close in case the regular home inspection didn't answer all of my questions.

20140223032412352904000000-o.jpg water heater.JPG
Answered by Jennifer Hogan
Posted Mon, 04/07/2014 - 17:44

Helpful? 1

Sizing the water heater to fill the largest tub in the house would be better & cheaper than a flash-heater. If it's marginal with the existing heater you can gain capacity by cranking up the temperature of the tank, and if it doesn't already have one, adding a tempering valve at the output of the tank to keep the scald risk bounded. Tempering valves between the hot water heater and any bathing or hand washing fixture are now required by law in most locations, but may not have been when that unit was installed. (A mixing valve at the sink or tub does not meet code as a tempering valve by itself.)

Answered by Dana Dorsett
Posted Tue, 04/08/2014 - 15:18

Helpful? 0

Thank you all for the great information!

Answered by Jennifer Hogan
Posted Tue, 04/08/2014 - 16:28

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