B · Glossary
Backup heater
A backup heater is an additional heater, often electric, that can support a heat pump system for domestic hot water, low outdoor-temperature operation or fault and emergency modes when the product design allows it.
A backup heater is an additional heater fitted to or controlled with a heat pump system. In home heat pump paperwork, the phrase often means an electric heater in the indoor unit, hydraulic module or cylinder package, with its own capacity, power supply and controller settings.
Category
Heat pumps and heating
Applies to
Heat pumps & AC
Last reviewed
03 Jun 2026