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# Sizing a heat pump

#1
02-11-15, 11:33 AM
Member
Join Date: Dec 2011
Location: Usa
Posts: 236
Sizing a heat pump

Hello, I am new to heat pumps, I am going to be installing central air in my home and wanted to install a heat pump system as well. My main source of heat is hot water base board with an oil fired boiler, I use a coal stove as well. I performed two load calculations on my home, one that included my finished basement and one that did not.

Calculation without basement.

Calculation with finished basement.

As you can see, the heat load all but doubled with my finished basement. For cooling, a 2 ton system would be sufficient, even on the hottest PA days. However, if it drops to the 20-30 degree range, even with a 10kw heating coil, the heat pump would not put out enough btu(at 20 degrees, the 2 ton system with the coil is rated for 48,000 btu) That is 10,000 btu/hr short of what my load test is showing.

Since this is just going to be primarily a back up and off season system for heating should I just stick with a 2 ton system? If I size if off the heating need, it would put me at a 3 ton system which would be way oversized for cooling.

I don't plan on using the heat pump in temps less than 40 degrees, I may use it to keep a 60 some degree temp in the house if we are away any long period of time during the winter.

Thanks.

Last edited by Xandrew245x; 02-11-15 at 11:55 AM.
#2
02-12-15, 02:03 PM
Forum Topic Moderator
Join Date: Jan 2005
Location: Delaware, The First State
Posts: 14,247
Andrew, I feel there is something wrong in your calculations unless the basement is out of the ground.
If it is like the basements around here with only a couple of blocks out of the ground, no way should your heat loss nearly double. The same is true with the cooling.

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