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vandedav

Member
Mar 5, 2009
45
Southern Indiana
Hello all, haven't been on here in a while but would love to get your opinion on my current situation. We are looking at adding onto our house. We currently have a ~900 square ft house that is well insulated. I have always wanted to heat with wood but couldn't justify the expense of getting up and running considering it was only costing us about $600 per year to heat our place. We live in southern indiana and the winters are fairly mild. We get below freezing often, but never for to many days in a row. We are looking. At adding on to our house. The plan is to add a 30' x 30' split level addition off the side of our current place. The bottom level would have a walkout garage with the upper level being bedrooms and bathrooms. We would also have a partial attic room that would start out ad a playroom and storage that may eventually turn into more bedrooms.
What I am trying to figure out is how to heat and cool the place. I plan on insulating as well as we can, spray foam and the whole bit. I do not have a whole lot of windows in the design, so i shouldn't have to worry about to much loss there. In terms of the lack of windows for solar gain, we are in thick woods, so the sun doesn't get to the house very well. I have been considering a boiler with storage and either radiant in floor heat or radiators plus wall unit ac units in certain rooms. I would like to eventually add circuits for the old house to the new boiler.

A few questions:

Would a Garn unit be overkill for this situation?
If another boiler was used that didn't contain storage, could the sand under the slab be used as storage if it was surrounded by insulation?

I am sure I will have more questions as we get into the discussion. I appreciate all of your thoughts. Thanks.
 
I would say that a Garn Is probably overkill. It would work great but, it will take up a lot of room and cost a good deal more
than a small boiler with homemade storage. The slab will hold heat for a long time if insulated well but is still not the same as storage. If you were to use the slab as storage you would get temperature fluctuation. You would dump heat in the slab and eventually over shoot temp then you would wait for the temp to drop a few degrees below set point then dump more heat in.
With water storage you could keep a consistant temp. I've been heating my shop using the slab for storage but
out there a slight swing in temp is not a big deal.
 
How big of an issue do you think the temperature fluctuations would be with the layout we are looking at. The basement level with the slab would be the garage. With the second level being the living space. Would the temp flux be an issue up there as well?
 
If you had radiator panels upstairs you should be able to keep it a stedy temp up there. The biggest issue using your
slab for storage is controls and how much wood to use. I don't Know of any automated controls that would let you do you use the
slab as storage. It would all be done manually with a timer and the weather forecast in front of you. You cant pull the
heat back out of the slab so once the slab is charged your boiler still needs to heat upstairs and dhw if your doing that. That's why you should look into some real storage. 500 gallon would probably be enough for your situation.
 
vandedav said:
....If another boiler was used that didn't contain storage, could the sand under the slab be used as storage if it was surrounded by insulation?....
I wouldn't recommend this. Many possible outcomes and few of them are good. It is hard to beat good old water for thermal storage.
 
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