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Slant Fin Heat Loss Calculation App

mferrer Member Posts: 33
As an Instructor in Hydronic Heating, I stress the importance of heat loss calculations for sizing HW boilers. I've played around with the Slant Fin phone app and found it fairly easy to use although I haven't actually used it for a specific job as I am not a contractor.

I was wondering if any companies here have used it. Is it a reasonable heat loss calculation tool? I would only recommend it to young students for educational purposes, but would be interested if it is widely used. It is a free app. What other tools are commonly used?

Thank you all!


  • Leon82
    Leon82 Member Posts: 684
    It usually comes in a little higher than the manual j or fuel use survey. It was about 10000 btu higher than my field use calculation
  • Zman
    Zman Member Posts: 7,607
    The Slant Fin app is user friendly and reasonably accurate. It should work well for your application.
    For residential projects I usually use the one in Siggy's Hydronic Design Studio. I built a spreadsheet version that works well for unusual or very large buildings.
    "If you can't explain it simply, you don't understand it well enough"
    Albert Einstein
  • GroundUp
    GroundUp Member Posts: 1,959
    I think the Slant Fin app sucks. It's awful to navigate, and always 20-30% high. There is an online calculator at builditsolar.com that is right on the nose with manual J and is super easy to use, and obviously much more accurate.
    EBEBRATT-Ed Member Posts: 15,844
    I like Slant Fin, it is simplified but most don't want to take the time to do any heat loss so it's better than a guess that's for sure.

    Some say is comes in high in my experience it is conservative but not what I would consider high.

    Like any calculation if you don't put the right numbers in the result will be wrong

    Other tool ? The B & G "System Syzer" you can get the wheel or uses it electronically
  • Jamie Hall
    Jamie Hall Member Posts: 23,661
    For what it's worth, I have used the Slant/Fin app several times, and on several rather odd applications. So far it has proven to be remarkably close to reality, The one thing I would say about it is that it is deceptively simple, and this can be a problem. If one doesn't pay attention to the numbers one is putting in and the assumptions which they are based on, it can be off. But then, so can any other calculation.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • mferrer
    mferrer Member Posts: 33
    Thank you all! I appreciate the comments. I will look into the other apps mentioned. Thanks for reminding me about the B & G System Syzer. I know I have one of the wheels somewhere. Just have to find it.
    Thanks again!