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Learning heat loss calcs - looking for infiltration factors

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Macro
Macro Member Posts: 7
edited December 2020 in Radiant Heating
So I'm learning about heat loss calculations and boiler sizing etc. but I would like to be able to do that calculations myself manually before relying on a program or online calculator. I am finding it impossible to find the infiltration factor multipliers anywhere though. Can someone direct me to them? I don't mind if I have to pay for a download or book but I can't find it. I'm an ICI plumber but trying to expand my resi knowledge and skills to grow my own business. Thanks!

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  • Alan (California Radiant) Forbes
    Alan (California Radiant) Forbes Member Posts: 4,004
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    This is how we used to do heat loss calculations in the "old days":
    https://heatinghelp.com/assets/documents/110.pdf
    Thanks to Erin, Dan and HeatingHelp for keeping this in their archives.
    8.33 lbs./gal. x 60 min./hr. x 20°ΔT = 10,000 BTU's/hour

    Two btu per sq ft for degree difference for a slab
    Erin Holohan Haskell
  • GW
    GW Member Posts: 4,693
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    Infiltration, that’s the wild west, unless you have a blower door. This is a basic fundamental, the taller the structure, the more infiltration. The older the structure, the more infiltration. It’s likely why the old-timers put these huge radiators in the front entry/hallway.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    gary@wilsonph.com
    MacroTinman
  • Macro
    Macro Member Posts: 7
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    Alan (California Radiant) Forbes said:

    This is how we used to do heat loss calculations in the "old days":
    https://heatinghelp.com/assets/documents/110.pdf
    Thanks to Erin, Dan and HeatingHelp for keeping this in their archives.

    Thanks! There's a lot of old and roughly built homes where I am that I think this would be useful for. Is there any other resources you can suggest for learning about this stuff? I see reference to "Manual J" sometimes but I don't know what that is!
  • STEVEusaPA
    STEVEusaPA Member Posts: 6,505
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    Alan (California Radiant) Forbes said:

    This is how we used to do heat loss calculations in the "old days":
    https://heatinghelp.com/assets/documents/110.pdf
    Thanks to Erin, Dan and HeatingHelp for keeping this in their archives.

    That one's too old, doesn't account for global warming. Neither does mine from the 80's.

    There was an error rendering this rich post.

  • Macro
    Macro Member Posts: 7
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    Do you have a recommendation for where I can find something updated? Or even wheat to search for?
  • Jamie Hall
    Jamie Hall Member Posts: 23,318
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    Macro said:


    Do you have a recommendation for where I can find something updated? Or even wheat to search for?

    I think at @STEVEusaPA was joking -- the basic concepts haven't changed a bit, global warming or no. The only thing really lacking -- and easily accounted for -- is better insulation in more recently built or upgraded structures.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 15,535
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    @Macro

    Doing a few calculations manually is a good idea. Anyone can plug in a program and get results , but they won't know right from wrong.

    Doing a few manually will give you an understanding of how it works.

    Slant Finn has an app you can download that people use that is pretty good.
    Macro
  • Zman
    Zman Member Posts: 7,569
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    Infiltration factor is always a bit of SWAG. The height of the building, location of the leaks, wind exposure and mechanical fans all play a factor.

    A blower door test eliminates many variables. comparing past utility bills to heating degree days is also a good trick.

    I like this article.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
    Alan (California Radiant) Forbesmattmia2
  • Macro
    Macro Member Posts: 7
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    EBEBRATT-Ed said:

    @Macro

    Doing a few calculations manually is a good idea. Anyone can plug in a program and get results , but they won't know right from wrong.

    Doing a few manually will give you an understanding of how it works.

    Slant Finn has an app you can download that people use that is pretty good.

    I was having a look through it and it seems pretty comprehensive, almost too much for me! I'm not familiar with all the different variables you can choose from (wall types mostly) so I need to dig into it a little more.
  • mattmia2
    mattmia2 Member Posts: 9,660
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    Some of the inputs to the heat loss are always a best guess. The r-value of windows and wall and ceiling assemblies are also a best guess.
  • RNB716
    RNB716 Member Posts: 8
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    I just went through this myself.... As a DIY project mind you. Without learning too much, lol, I found this to be of help.

    best of luck with your project.
  • Dave H_2
    Dave H_2 Member Posts: 556
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    Take a look here, we went into detail on heatloss during the first few sessions of Taco After Dark, Summer School
    https://www.youtube.com/watch?v=52VCNqchLGo&list=PLsbNhUC4lCm_2aouRyJRpKXFBNHmW5nN_&index=14

    Dave H.
    Dave H
    Macro

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