Heat Pumps

[ivanp]

Nope. It's not that simple, not at all. The C.O.P. number (usually about 4-4.5 for bigger modern heat pumps, 4.5-5 for small units) is how much heat generates per kwh of electricity spent, measured at +7C. Come +2C and this coefficient drops down to about 2-3 all heat pumps. It's a curve, most manufacturers provide it somewhere in tech docs. Basically the colder outside - the lower efficiency.

[Learning]

Nope. It's not that simple, not at all. The C.O.P. number (usually about 4-4.5 for bigger modern heat pumps, 4.5-5 for small units) is how much heat generates per kwh of electricity spent, measured at +7C. Come +2C and this coefficient drops down to about 2-3 all heat pumps. It's a curve, most manufacturers provide it somewhere in tech docs. Basically the colder outside - the lower efficiency.

I stand corrected. The efficiency drops off as the outside temperature drops below 7 degrees but the energy cost remains the same. The heat pump will draw the same power but its heat output per KW used will drop as Ivanp says.

Makes sense when you think about it. Its gathering heat from the outside so the colder it is outside the longer it has to work to gather that heat.

So, worst case scenerio for power consumption remains the same. Running the heat pump on full at a temperature its not going to reach, all day, with windows open, it makes no difference what the outside temperature is. It can only draw its maximum power consumption as calculated earlier by Bob.