Grantanow
If you have a heat pump I assume it fails if the electricity supply goes off and then takes a long time to re-heat. Makes me unlikely to buy one.
Heat pumps should only be installed in highly insulated houses.
In which case the highly insulated house would hold the heat for a long time if there was a power cut, so you would not be cold unless it was a very long power cut and when the electricity came back on the slower heat again would not be a problem.
If you had a less well insulated house with storage radiators or instant heaters, they would heat the house more quickly when the power comes on, but because these types of heating are generally in less insulated houses, the house would cool down and be much colder when the power was off.
Have a wood fired stove as a back up heater.
