[Beached]

a lot of heat pumps in usa are air to air and have an electric heater in the heat pump to generate the heate when temperatures get so cold that air to air is not effective. without a geothermal system to extract the heat from, they get very expensive to run in very cold Temps when compared to gas hearing. Hensel why the myth that they don't work. no one thinks they don't work, they just think it's a worse solution than natural gas.

[8fingerlouie]

My Air to water heat pump also has a backup resistive heater built in, which kicks in around 0C. It doesn't fully switch to it until -15C, but uses it for assistive heating for things that cannot wait, like hot water.

Still, i use way less energy than i did with natural gas. The original estimate from the installer was that the backup heater would consume around 100 kWh during normal year, and considering my estimated "heating needs" of 13,000 kWh per hear, that's just a tiny fragment of that. Resistive heat is (almost) a 1:1 conversion of energy from electricity to heat, and the heat pump delivers a COP value of between 3.5 and 4, meaning i spend around 3500 kWh on the rest.

For comparison, 1m3 of natural gas contains roughly 10.5 kWh of heat energy when burned in a gas boiler, so to deliver 13,000 kWh of heat, i would have to burn 1250m3 of gas.

Where i live, in Scandinavia, electricity is around $0.13/kWh and natural gas is around $2.2/m3 (both including taxes), so in total it works out to :

- Gas : 1,250* 2.2 = $2,750 / year

- Heat pump : 3,500 * 0.13 = $455 / year

Gas is about 6 times as expensive as a heat pump here.