Always a good feeling when your calculations translate to real life.
Used the ResCheck program available for download for free from the DOE. http://www.energycodes.gov/rescheck/
It's a great program intended for calculating whether your new home or addition will meet energy standards. But it also will then calculate the building's heat loss. Wanted to to a heat loss calculation on my house now, and on my house when I'm done w/ the new windows, additional insulation, etc.
Did the heat loss check, and the calculation came out w/ my house needing 32000 BTU when it's -10 outside, or about 28000 when it's 0. It was a steady 0 degrees last night. No stove on, no dryer running, etc. Timed the furnace cycles a few times and found it was using about 27000 BTU. I couldn't ask for any closer than that!
The only problem of course is that the furnace is putting out 56000 BTU. I'll put this unit in the garage and change it out for a 36000 BTU output 2 stage model next year. I was planning on buying a furnace for the garage anyway, but this way I'll save money on the house heat w/ a better sized furnace. House will be better insulated too, only requiring 26000 BTU at -10 degrees, so I still will have plenty of headroom, but I can't get a smaller furnace.
Just thought I'd share the ResCheck program.
Last edited by Nate R; 02-21-2008 at 10:28 AM.
I haven't used the DOE software, but over the weekend I found, downloaded, and used the rather user-friendly heating loss calculator from Slant/Fin.
I found this by reading the HVAC section of a messaging board used by heating contractors, and apparently it is well known.
It is free at http://www.slantfin.com/heat-loss-software.html.