Your heat pump is designed to run efficiently until -10°C,-15°C, or -25°C (without wind chill) depending on which model is installed in the home. All heat pumps require an alternative source of heat. The system can work efficiently until these temperatures are reached. At that time, some systems should be shut off, while others will automatically do so. Running electric baseboards or other sources of heat is necessary approaching these temperatures.
During cold winter months (February & January) a power bill should be expected to rise as the system has less ideal temperature to run. The entire season’s results will show savings. Relative to outdoor temperature and where the heat from a system will travel, it may also be necessary to run heat sources (ex. Electric baseboard) in other parts of the home. Don’t worry, as these sources will only be supplementing at a fraction of their regular use. To some measure, heat from the ductless system will reach these areas, and less heat is produced by the alternative (such as electric baseboard) in order to reach a comfortable temperature.
We recommend all systems be shut off at -15°C (with the exception of our cold climate heat pumps), this will assist the lifespan of the unit as it works hardest during colder temperatures. This will also maintain efficiency of the unit, as at this temperature the cost of operation is the same as electric baseboards.