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What size boiler.

jtpfarm Member Posts: 35
Have a new home in progress. 60x40 main level plus a full walk out basement. 8' basement height and 9' main level height. The main level has 3" of spray foam all the way around and 30" of insulation in the ceiling. Basement has 1.5" on the underground walls, 4" between the floor joists, and 3" on the walkout wall. All floor heat.

How many BTU do I need?



  • Ironman
    Ironman Member Posts: 6,555
    You need to do a heat loss calculator based upon ACCA manual J.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    HVACNUT Member Posts: 4,190
    Oil, gas, heat pump, geothermal?
    Hydronic, hot air?
    Download the Slant Fin heat loss calculator.
  • jtpfarm
    jtpfarm Member Posts: 35
    L.P. gas is what I'm using.
    HVACNUT Member Posts: 4,190
    Download the Slant Fin heat loss app. Its free. If you get hung up on anything, in the Contact us section. Slant Fin will help.
    You can't use sq. ft. alone to calculate a heating or cooling load.
  • Paul48
    Paul48 Member Posts: 4,470
    You have put the cart before the horse. Maybe @Rich would be so kind as to show you the amount of work that he puts into designing a radiant system?
    EBEBRATT-Ed Member Posts: 10,253
    A heating system is an investment. Do you want it to work or do you want a hack job? Your choice. Get started right and do or have someone else do a heat loss. Sound like you need a qualified designer
  • Gordy
    Gordy Member Posts: 9,514
    edited December 2017
    This should have been decided pre construction sure things do not advance to far in which limits latitude in choices.

    As others said do the heatload calc. Room by room. Each room will have its own btu load.

    Then you have to decide what type of floor radiant. Many different details. I recommend sandwich, or panel method. Basement in the concrete. Concrete without pex is a shame.

    The heat loss will tell the designer many things.

    Tube centers
    Tube diameter
    Flow rates
    Boiler size

    Speaking of zoning what are your likes, or needs as far as controlling temps in different rooms.

    Speaking of zoning again. Be sure not to have zones in which loads are less then the minimum modulation of the mod/con boiler you choose.

    Speaking of boilers do you want a high efficiency, or mid efficiency?

    That’s just a start.
  • mikeg2015
    mikeg2015 Member Posts: 1,183
    What location (part of country)? Propane costs almost as much per BTU as straight resistance electric in some area with cheaper electric rates. Might make more sense to get a reverse cycle air cooled chiller or invest in geothermal water to water. UNLESS... you have a lot of power outages. Then you might still use propane for backup.
    HVACNUT Member Posts: 4,190
    Lots of good information here.