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I have a new Rheem 2.5 ton seer 12 heat pump with the high efficiency air handler. The system ended up with a 13.7 seer rating with the air handler coil combo. My question is: at about what outside temperature does the efficiency of the unit fall below 100%,or have a COP of less than 1?

I am heating a new 2200 square foot home ICF home with R-50 walls and R-50 cellulose in the attic. The house has good doors and windows(low e argon filled). Yesterday morning the outside temp was 1 degree above zero and the unit was running approximately 50 percent on, 50 percent off. At 30 degrees it runs about 25 percent of the time, so it has not been anywhere near reaching the balancing point. Because this house requires a fairly small amount of heat, I am afraid the balance point of the house may be lower than the point where the COP is 1.0. Yesterday we had a 52 Degree heating day, and I only used 29 kWh, including the use of lights and power tools, as we worked in the house all day, carrying dry wall in from outside, etc.

As odd as this seems, if this happens the heat pump may be able to keep up, but the strip heaters might be more efficient. I cant find any info on this, just wanted to see if anybody out there has any comments on this.

John
 

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COP
Coeff of Preformance. SOmple calculation BTU/HR DIvided WATT/hr Divided by 3.41. = COP. THis is the amount of efficency gain above electric heat.1=1
 

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bigdogx01 said:
COP
Coeff of Preformance. SOmple calculation BTU/HR DIvided WATT/hr Divided by 3.41. = COP. THis is the amount of efficency gain above electric heat.1=1

yes but how is he supposed to determine the btu output of his heat pump at 1 degree farenheit? the ari listings may have output (under perfect circumstances) at one or two temperatures
maybe you could "interpolate"

i can tell you that 50% on cycle is "kickin butt" at that temperature though
id let it run
 
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