Alan Gage said:Thanks for the replies. I realize I'll have problems getting long burns from such a small firebox but I'm ok with that. If I have enough coals left over in the AM to light some small splits I'll be happy. I actually prefer a house cooler than most. 70 degrees and over I start getting uncomfortably warm.
BK - An average heat output of 1/3 or less from peak over a burn cycle would give me lots of room to play so that's good news. Even if it averaged 1/2 of peak output I should be sitting pretty.
Jimbo - Good point about the amount of time the outside temp actually stays at the design temp. It was colder than average here this winter but we never made it to -20. Lots of nights of 10-15 below and highs around 0. Last year we hit it a few times as well as setting a record of -32. But like you said, it doesn't stay there long. I've tried running the numbers with design temps of -10 and -15 and it certainly helps out.
You're right about calculating air loss, that will be the wild card. I'm going to be very careful about building a tight envelope. The plan is 2x6 walls full of cellulose insulation, OSB sheathing, housewrap, and at least 2" of rigid foam on the exterior (with taped seams). That will give me another R10 as well as creating a thermal break for the studs. Flat ceiling with at least R-60 blown in. I've never lived in a well insulated and tight house so I'm really interested (excited actually) to see how well it holds heat.
I'm also worried about the stove being too hot for the majority of the burning season. I'm used to burning 24/7 from December through the end of February. I'm afraid the house will hold heat so well that except in the coldest weather the coals will be burned down to nothing before it's time to reload. Which will mean starting a fire from scratch most of the time, which is a pain. That's one of the reasons for wanting to place it by some windows, to let some of that heat get away. But I don't want to lose too much of it and run out of BTUs when it gets really cold. I suppose I can always break down and turn on the backup heat if that's the case.
I guess there are worse problems to have....like trying to heat my current house with the wood stove when it's -10 and the wind is howling.
Thanks for all the great info everyone!
Alan
I'm not an expert but I've always heard cellulose with settle significantly over time. The builder insisted on using some in the ceiling and we finally agreed on R19 fiberglass with R30 equivalent of cellulose on top. I think I will regret not demanding R38 or higher fiberglass. I actually installed R38 in my pole barn and I think the builder concerns with leakage between the batts was silly. My walls were R19 (2x6) fiberglass. Now I see Owens Corning has this ATTI CAT type. Basically it is shredded fiberglass that blows in with a machine but it not supposed to settle and not as dusty to install. My local mom & pop lumber yard is advertising it now too. If you put cellulose in your wall cavities I think you can expect it to settle several feet over 10 years causing great heat loss. Research this a little more, sounds like you have a great plan for a nice well insulated home that will be easy to heat with your woodstove. I just wouldn't want you to be disappointed with the performance due to settling of the cellulose.