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Calculating Manual Load for Heating

Crissie
Crissie Member Posts: 96
Hi, Looking for a free web based app so I can calculate / validate the my heating BTU's need. Getting different feedback from different contractors. The SlantFin web app doesn't work, it is frozen. Does anyone know of a different app? Thanks!

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 16,590
    As I said in your other thread, don't try to use it on a smartphone. Download the program to your PC.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • Crissie
    Crissie Member Posts: 96

    As I said in your other thread, don't try to use it on a smartphone. Download the program to your PC.

    I tried using it on a Desktop computer. It froze. unfortunately isn't working.
  • ratio
    ratio Member Posts: 2,871
    And as I said in your other thread, use the phone app. :wink::smiley::sweat_smile:

    Seriously, I can't speak about the web app, but at least the Android version of the phone app works. For me.

    Canucker
  • KC_Jones
    KC_Jones Member Posts: 4,695
    edited October 10
    I didn’t think the desktop one was even supported anymore?!  I tried getting it a couple years ago and it didn’t work then.

    The phone/tablet app works great, I just opened it again to verify and it’s all good.

    2014 Weil Mclain EG-40
    EcoSteam ES-20 Advanced Boiler Control
    Boiler pictures updated 2/21/15
    Crissie
  • CMadatMe
    CMadatMe Member Posts: 3,084
    edited October 10
    To figure out the loss through a outside panel. ( Design Temp Indoor - Design Temp Outdoor) / Panel R-Value = Btu/hr Loss per sqft of outside panel. Take that and multiple by the total sqft of the panel. Make sure you take out windows, doors and plug them in separately. Then add all the losses together for the total outside panel loss. Yea, its that easy. Don't forget to calculate both ceiling and floor loss should there not be a conditioned space above or below

    For infiltration factors. Per ASHREA .35 to 1. Take the cubic ft of the room x the factor. (R-19 Wall or tighter use .35, R-11 I'd use .75. Now add that to the rooms total outside panel loss and boom you have a basic launch point for the heat loss of the room. Software is great to save time but it's also carries fudge factors so they are about as accurate as doing the actual math manually. Do it both ways and let me know how far they fall apart.

    This would be no different than using Longest run x 1.5 x .04 to figure circ pump foot of head for the critics out there.
    "The bitter taste of a poor installation remains much longer than the sweet taste of the lowest price."
    Crissie
  • Canucker
    Canucker Member Posts: 698
    CMadatMe said:

    To figure out the loss through a outside panel. ( Design Temp Indoor - Design Temp Outdoor) / Panel R-Value = Btu/hr Loss per sqft of outside panel. Take that and multiple by the total sqft of the panel. Make sure you take out windows, doors and plug them in separately. Then add all the losses together for the total outside panel loss. Yea, its that easy. Don't forget to calculate both ceiling and floor loss should there not be a conditioned space above or below

    For infiltration factors. Per ASHREA .35 to 1. Take the cubic ft of the room x the factor. (R-19 Wall or tighter use .35, R-11 I'd use .75. Now add that to the rooms total outside panel loss and boom you have a basic launch point for the heat loss of the room. Software is great to save time but it's also carries fudge factors so they are about as accurate as doing the actual math manually. Do it both ways and let me know how far they fall apart.

    This would be no different than using Longest run x 1.5 x .04 to figure circ pump foot of head for the critics out there.

    I agree with that. As much as I like using the Slantfin app, it way over estimates infiltration unless you're aggressive with the numbers. The number it spits out is my max range and would try to find a unit the size below. @Crissie has the advantage of already knowing an accurate infiltration rate
    You can have it good, fast or cheap. Pick two
    CMadatMe