woodstove and geothermal unit

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rmcfall

Feeling the Heat
Nov 28, 2005
308
In our new house I plan on installing one of the soapstone stoves (probably the Fireview), which will heat the family room, dining area, and kitchen. Some of this heat will make its way to the bedrooms, but probably not much due to the layout (ranch style home). I am trying to determine what sort of HVAC to put in since the existing furnace is shot. The unit will heat 4 bedrooms and a basement since the woodstove will do the rest. I have considered a 16 seer Carrier heat pump, but am also wondering about geothermal units. The HVAC contractor I am working with installs both heat pumps and geothermal units, but stated the geothermal might be a waste of money since I would have the woodstove. I am wondering whether anyone here has both a woodstove they burn 24/7 and a geothermal unit? If so, are you recognizing any payback from your geothermal unit?
 
I looked into a geothermal unit, gave that idea up for a wood stove.

Geothermal is an expensive option, and works best in slightly cooling dominated climates, not heating dominated ones. First, they're expensive. To be practical they need to save you money in winter and summer so you get double duty return on your investment to cover their initial costs. The reason they do better in cooling dominated climates is that as they cool your house you get more returns as the heat generated from cooling can be used to heat your domestic hot water so it performs double-duty in cooling mode. Whereas heating mode the cold created isn't used for anything so you get more return running in cooling mode than heating. In the north our ratio is like, 6000-8000 heating degree days and 400-600 cooling. In summer, it would hardly be used for cooling your house much in the north, which means in summer you need another source for domestic hot water. It also means you will only get less than half the payback of someone in the south. The next reason is soil temperature. If it's 30 outside and you live in the south your soil temperature is probably 60. A little more efficient for the geothermal to transfer that heat into the living area. Whereas, in the North you soil temperature may be 50. Not as efficient pulling the heat out of the 50 degree earth. Up north that makes it great for cooling, however you don't cool very often up north. It is more efficient than an air heat pump but also more expensive. Geothermal uses a decent supply of electricity which hinders payback time since electricity is expensive (but not as much as an ac unit or electric heat).

I did a payback of a geothermal unit, I live in the north. Cost for installation, convert my house over to HVAC, drill 9 holes into the ground, installation was estimated to be $24,000 IF they didn't hit rock which I live on rock. Doing a heating degree cost analyses vs. cooling my estimated savings/payback going to geothermal was 211 years! I then looked into Solar, which is the best form of heating, but like geothermal not cheap. Sure, the solar panels are cheap and use little electricity, but you need to have a new roof, radiant floor heating, new efficient windows, well insulated attic, floors, and should have insulating window shades so although a solar heating system is cheap the other stuff that you have to do for it to be feasible is not. But, at least with solar those things are things you should do anyway and I'm about 65% there to being able to heat with solar.

So, if you live in the north I wouldn't consider geothermal. Maybe put in another wood stove, think about solar, put in radiant floor heating, the do-it-yourself strap up kind, maybe consider a solar hot water heater which doesn't require all the things to your house solar heating does. If you live in the warmer middle-states, or south, then geothermal may be practical. Last month I saw someone on the web building a house in Canada very excited about the Geothermal heating system they decided to have installed in it, I felt bad for the couple, it's not going to work like they think it will, of all places Canada.
 
Thanks for the response. I live in Kentucky, so I guess I would probably see more of a payback. The system I am looking at doesn't cost near as much, but is still expensive...about $14,000. I really enjoyed burning wood in our previous house, so I look forward to doing it again in our new house. Doing so, however, might make putting in a geothermal unit a waste... hard to say I guess.
 
We have discussed this before what I would do is zone your HVAC system with a zone damper thermostatically controlled, one for the bedrooms and one for the wood stove area. If you effectivily use the wood stove, it will heat enough, that your thermostat for that zone will never turn on. When you are not home to attend to the stove, you will have that zone covered by central heating. The other reason is to zone your AC. You want suggestions weight out this one. Another option does the same thing, two complete systems two heater/ ac units that split the heating/ Ac load.
 
I plan on doing just what you said with regard to the zones. What I am wondering is...would a geothermal system be a waste of money in contrast to a regular air to air heat pump? I know that without a woodstove a geothermal system is the way to go. With a woodstove, however, I am not sure...maybe just an air to air heat pump would make the most sense....??



elkimmeg said:
We have discussed this before what would do is zone your HVAC system with a zone damper thermostatically controlled one for the bedrooms and one for the wood stove area. If you effective use the wood stove it will heat enough that your thermostat for that zomne will never turn on When you are not home to attend to the stove you will have that zone covered by central heating. The other reason is to zone your AC. You want suggestions weight out this one. Another option does the same thing, two complete systems two heater/ ac units that split the heating/ Ac load.
 
To help, I looked up the data KY.

Northern KY (Jackson) is 4358 heating degree days and 1059 cooling, Southern KY (Paducah) is 4192 heating and 1533 cooling and that's averaged over the last 30 years. So northern KY is 80% heating, 20% cooling and Southern KY is 73% heating 27% cooling. Still, heating dominated but better than where I am.

All that really matters is, your payback won't be as quick as if you were say 60% cooling and 40% heating going Geothermal but does that matter to you. Geothermal is a green energy source, and you'll be doing your part to help the environment and improving the world by getting it over other choices. I was willing to pay extra for it to be "green", just not as much as I was quoted!

:)
 
I think Geothermo would be a waste of money. I'm willing to bet your wood stove, if centrally located in your new home will heat your whole house, since your not in too cold of a climate. $14,000 can buy alot of firewood! Go with the Carrier for back up or zone heating.
 
Thanks for looking up the data on Kentucky. I was under the impression that most of the payback for geothermal systems came from money saved during the winter months, and that less payback was recognized during the summer months. It sounds like I am mistaken?

Anyway, I think you all are right--that geothermal would probably be a waste of money. I hope you are right, Todd, that the Fireview will heat most of my home. It won't be centrally located, but the living areas of my home will be completely open to each other (once I am done with it), so I have no doubt the stove will heat these areas real easily. Whether it gets into the bedrooms or not is another story, but that's where the zone system comes in...

Speaking of the Fireview, the specs on Woodstock's site don't say it heats nearly as many square feet as it sounds like the stove will actually heat. From the sound of your posts, you seem to have really enjoyed that stove, haven't you?
 
rmcfall said:
Speaking of the Fireview, the specs on Woodstock's site don't say it heats nearly as many square feet as it sounds like the stove will actually heat. From the sound of your posts, you seem to have really enjoyed that stove, haven't you?

I was concerned with those numbers also. Woodstock said there are so many variables on heating sq footage they went with a very Conservative number. If you have good insulation and open floor plan it will heat much more. Mine is heating 1800 sq ft with ease.
 
Correct, geothermal is most beneficial in cooling mode because while it sucks the heat out of your house it transfers that heat into your domestic hot water. Two birds with 1 stone and faster payback. Whereas having it in heating mode, creates cold which can't be used for any purpose and transferred into the ground.

You may be experiencing the identity issue of geothermal. The system you're referring to started out being called geothermal, but changed recently to geoexchange. Mention geothermal to people and they think Iceland, with lava, free abundant heat, steam. Tell them you're thinking of a geothermal unit for your property and they think you're crazy trying to tap into lava reserves below, "How deep do you have to drill!". Also, it was tough for people to get over the "geothermal" name and it being able to "cool" your house having visions of lava and steam. Hence, renamed to geoexchange and the "geological exchange of heat from one source to the other". Whether that be heat from the ground into your house, or heat from your house into the ground.
 
Two comments -

First on heating w/Fireview: We heat about 2000 SF with the Fireview centrally located; fairly open floorplan to stove. (~800 SF closed off in winter unless we have guests) Bedrooms stay about 5 degrees cooler. Oil heat kicks in only when highs are 20 or below and we have to leave the stove untended for > 8 hours. (nice thing about this stove is you can have good restarting coals after 12 hours+) Fairly new construction, in lower NY state, lots of windows... your mileage may vary, but in KY, I think you'll have no problems heating 2000 SF if well insulated and you can load at least every 12 hours.

Second on a similar topic to this thread - has anyone tried or seriously sized using solar HW for supplemental baseboard heating? I know it's hard to accomplish substantial heating through it, but we wouldn't mind using some supplemental baseboard heat more often if it could come off solar HW loop. Interestingly, the coldest days also tend to be the clear sunny days/nights and the longest periods where we can't tend the stove is during the day while we are at work so that part lines up fairly nicely for us. (I've noticed that cloudier days in these parts often tend to be warmer) Wondering if having some extra solar HW capacity to circulate say 140 deg. water through our baseboards might do the trick even on the really cold days to help carry the house a little longer before having to call for oil heat. Haven't analyzed the heat potential in detail yet, but wondering if anyone else has.

-Colin
 
Colin I like your point, (solar hot water heat) together after we iron things out It can be done. The other thing one can do for your bedroom, is place a small box fan on the floor aim it towards the stairs or stove. By mechanically removing colder heavier air, you allow warmer lighter air to replace it. Same job your Hvac system should be doing. Expanding it further, I can tell you many ways to insrease your effeciencies and save you money, High low returns with mechanical dampers. Lets design the most effecient cost effective system.

Colin solar hot water heat works with FHW systems but is a b_- ch to convert to FHA /AC systems, But I like your thinking
 
Thanks for all the feedback everyone...the Fireview really sounds like the way to go. I was looking at some of the other soapstone stoves for awhile, but the Fireview seems to get nothing but rave reviews...
 
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