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Sizing heat pump

I just did a manual J heat loss Heat gain for a house. The heat load was 32,078 and the heat gain would be 17,289. So do I do a 2 ton heat pump and the rest in electric back-up? Second choice, 1-1/2 ton heat pump and 15K in electric back-up or 2.5 ton heat pump with a little back-up?


  • Ironman
    Ironman Member Posts: 7,375
    What's the total SENSIBLE heat gain? You must size the heat pump to cover both the sensible and latent loads and consider them separately.

    Usually, in a residence, the sensible is 90% or more of the total, but a typical heat pump today has about 75% sensible capacity and about 25% latent. So, you don't look at the total for the structure and then look at the total for the equipment. That's a common mistake.

    Look at the sensible and latent capacity of the heat pump and make sure it's sufficient to match both the sensible and latent loads of the house.

    If 17.3k btus is the TOTAL heat gain of the structure, then you're probably gonna need a 2 ton heat pump with a 10kw heat pack.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    John Mills_5
  • megajennyposts
    megajennyposts Member Posts: 4
    Your calculations help me with the heat pump installation.