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Range for Acceptable K factor?

bob_46 Member Posts: 813
Dave, I'm not sure what you mean by K factor. K=1000? In heat load parlance
k= conductivity or the amount of heat transfered through a HOMOGENOUS material, in BTU /SQ.FT. /Fº∆T/ IN. thickness. Which K are you refering to?


  • D107
    D107 Member Posts: 1,800
    With old, oversized boiler

    I calculated heat-only K factor of 8. 25 year old WM Gas 210K firing rate, 143K net, 40K heat loss. Tightened envelope, sealed chimney etc. Probably brought it down from 11 before. Foaming attic will likely bring it down another notch or two. I'm stuck with this unit probably for another 3-5 years.

    What kind of numbers are you seeing with Mod-Cons?


  • D107
    D107 Member Posts: 1,800
    similar to your forumula but not Delta T

    793therms/yr x 100Kbtu = 96,100,000btu/5467DD/1800sqft = 8.06 btu per sq/ft per DD. Thanks. I'd guess that modcons in a well insulated house could get down to a K factor of 4.


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