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Calculating Actual Heat Loss

Post in 'The Boiler Room - Wood Boilers and Furnaces' started by jebatty, Jan 4, 2012.

  1. jebatty

    jebatty Minister of Fire

    Joined:
    Jan 1, 2008
    Messages:
    4,510
    Loc:
    Northern MN
    My data on weighed wood burns might have induced some of you to also do this for a sufficient period of time to use that data to calculate actual heat loss. My boiler and storage are inside the heated space. For Nov-Dec I burned 3014 lbs of wood. That works out to 12,455 btuh actual heat loss (3014 x 6050 / 61 / 24). Degree days in my location for these two months were 1993, which also means, fwiw, 6.24 btuh/dd. My shop is kept at 60F, so my heat loss does not represent an equivalent house.

    If some have boiler and storage inside the heated space and could do the calculation, and others have the same outside the heated space and do the calculation, we might start to get a better idea of the contrast from a heating perspective of boiler and storage location.

    You might want to try weighed wood burns for awhile and see what the result is for actual heat loss for your home or other building.

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  2. ihookem

    ihookem Minister of Fire

    Joined:
    Jan 25, 2009
    Messages:
    594
    Loc:
    Allenton, Wisconsin
    I have weighed my wood a few times. I also figured what my btu needs were. I figure an 80% efficiency with my eko 25. My boiler is 120' away so that makes a difference. I still wonder were I can find a good heat loss calc. on the internet. I use build it solar.com I think it' a good heat calc but want others to compare.
  3. Hunderliggur

    Hunderliggur Minister of Fire

    Joined:
    Dec 23, 2009
    Messages:
    602
    Loc:
    Lothian, MD
    I used REScheck from the Department of Energy to establish the code compliance for my log house to our local building department. At a UA of 834, I am 6% better than code without taking into account my solar orientation. UA 834 at 50F delta T (70 indoor, 20 outdoor), is about 40KBTUH. At 3 GPM and delta T of 20 in my radiant, I get about 28KBTUH per zone. Today it was more like 10F outside so my loss is 50KBTUH which is consistent with my zone pumps running most of the time.

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