A properly sized heat pump optimally heats or cools a space under average operating conditions. However, in extreme conditions such as very low outside temperatures, an electric heater or other additional source (if already installed in the building) always makes sense, especially for air/water heat pumps. 

What are the advantages of installing an electric heater or supplementary heating source?

• 100 % Heating safety.
• The economics of heating in extreme conditions, where the heat pump operation can no longer cover the heat losses or is uneconomical to operate under such conditions.
• Heating operation in case of heat pump failure.
• The electric heater in air/water heat pumps is also welcome at the start of the heating system.
• In winter, because the heat pump cannot raise the temperature of the heating water sufficiently to heat the room and defrost the outdoor unit in a shorter time.
• But be warned, an electric heater is not a substitute for a lower power pump. If the heat pump is underpowered, the electric heater has to cover too much of the heating needs of the building, which leads to a reduction in the economic efficiency of the heating.