Heat Pump Temp Economic Balance Point

[weather777]

Can someone please tell me how to determine the proper economic balance point for switchover temperature on a dual fuel (electric/propane) heat pump ? Its currently set at 40 degrees,but with propane at $2.90 gallon and electric at 9 cents KWh I doubt this makes sense.Is it difficult for a lay person to lower the switchover temperature themselves?

Thank you

[Bill Arden]

had to think for a moment... you mean an air source heat pump switchover due to outside temperature.

To calculate it you would have to know the systems COP(multiplier) value at each temperature or how much Btu's per Kwh it puts out.

The SSER number is only the average over a season and can only be used as a shopping guide.

[weather777]

Thank you --Yes ,that is correct.

The COP for 70 degree inside (we keep it 65,but COP not available)


OUTSIDE COP

10 degrees 2.15

20 degrees 2.65

30 Degrees 3.11

40 Degrees 3.53

[Bill Arden]

Next you have to convert to BTU's per $

>propane at $2.90 gallon
Next we need the furnace efficiency.


>and electric at 9 cents KWh
>10 degrees 2.15
>20 degrees 2.65
>30 Degrees 3.11
>40 Degrees 3.53

1 BTU = 0.00029307107 kilowatt hours
1kWh = 3413 BTU

So at 40 degrees you get...
(3413 BTU * 3.53 COP) / ($0.09 for one kWh)= 133,865 BTU's per $1
And at 10 degrees you get...
(3413 BTU * 2.15 COP) / ($0.09 for one kWh)= 81,532 BTU's per $1