Pellet stove question
Ok…getting closer to getting the house project buttoned up and we still have to get the HVAC system back up with all the ducts as they were removed during the gutting process. We’ve decided to keep the HVAC system instead of going with my dream of a hot water system due to the responses from other questions on this forum.
My question is: would a pellet stove installed now keep the house warm enough to prevent freezing of the pipes and such? The walls will be approx R-20 and the ceiling in the second floor approx R-60 with an uninsulated field stone foundation (uninsulated for now).
I’m thinking I could install a pellet stove quickly as it is getting colder and then have the freedom to install my duct work at a less stressed pace. I’m having a hard time finding someone who really knows what they are doing in this field to consult with as far as duct layout.
House is a 1,500 sq foot four-square with hip roof, balloon framed, with updated windows. Thanks much!
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Geoffrey,
Unless your home has air barrier defects or poorly located water pipes, a pellet stove should have no problem keeping your house warm enough to prevent freezing pipes.
However, you didn't provide all of the details. Where are you located? You will face more of a challenge in Fairbanks, Alaska or Yellowknife than you would in Boston.
Most problems with freezing pipes occur when a pipe is located near an air leak. Typical problem areas include rim joists in crawl spaces or basements -- if you have a pipe near the rim joist, you had better have done your air sealing work well -- or any plumbing pipes located in exterior walls.
I'm in Northeast Wisconsin. Like I said I do have stone foundation walls and the rim joists/sill plate area will be insulated and air sealed as much as possible before winter but the foundation will not. the foundation is about 4'6" under the ground in the basement and there are some old windows which I plan on replacing. The only plumbing I plan on having actually near the exterior walls will be a toilet waste line and a vent for that same line..
but that will be in a soffit starting 5" to the interior side and beyond the insulation.
Like anything else, you have to do the math. Run a quick & dirty heat load calc on the above grade portion of the uninsulated foundation, which will probably be at least a quarter, and maybe even half the heat load of the whole house, and size the BTU-output of the pellet stove accordingly. Run the numbers on a 45F interior temp, and your 99% outside design temp.
Eg: assume your outside design temp is -10F, interior temp is 45F, and you have ~145' of foundation perimeter with an average of 3' of exposure. That's a delta-T of 55F, on ~435 square feet of foundation. A foot thick stone foundation has an R value of about R1 a U-factor of 1/R which is also about 1, so it loses about 1 BTU per square foot per degree, making the heat loss U1 x 55F x 435'= ~24,000 BTU/hr. The losses per square foot of the rest of the above grade walls are probably a 10th of that per square foot when you include window losses, but you're probably talking 4-5x more square feet. A 50-60KBTU/hr pellet stove would more than likely cover the whole shebang.
Or, do a spreadsheet on the whole house, using the real U-factors for the construction type & R-values, and the published U-factors on the windows & doors, and add a fudge-factor for infiltration. That'll show you pretty clearly just what an energy-sink uninsulated foundations are, even if you let the basement run cold and only heat the upper floors. Heat loads of uninsulated basements in excess of 20K are pretty common, even with 45F temps in the basement it can be more than a quarter the heat load of an otherwise code-min house.
I wonder if it's allowable to heat a house off of just pellets to start with? I'll find out. Another question..running the basement cold isn't an issue except for the pipes...do you think the first floor at 70 degrees would heat the basement enough to prevent it from freezing solid?
Geoffrey,
Yes, a well-insulated home can be heated with a single wood stove or pellet stove, as long as the design is compact, the house has a fairly open plan, and the bedroom doors are left open during the day. For more information on heating with wood or pellets, see All About Wood Stoves.
During very cold weather, your basement might freeze if it is not very well air sealed. This problem is prevented in many older houses by having at least one heating appliance in the basement. Even a water heater makes a big difference. But if you have no heating appliances at all in your basement -- no furnace, no boiler, no chest freezer, and no water heater -- your pipes can freeze, unless you track down all of your air leaks and seal them.
By "... allowable to heat a house off of just pellets...", I presume you mean "allowed by code" from a certificate of occupancy point of view? That certainly WILL VARY by location- wouldn't count on it. But many small tight homes in cold climates are heated solely by pellet stoves.
What Martin said about the temperatures in the basement- a basement that leaks a lot of air could potentially freeze at 10F or lower outdoor temps even with a 70F room above it, but if air sealed it would have to be a lot colder. It just depends.