Hybrid heating (heat pump with boiler)
A hybrid heating system combines a heat pump with a second heat generator, such as a pellet boiler. This is particularly useful at high flow temperatures.
- Heating load of the house: the colder it is outside, the more heat the house needs.
- Heat pump output: it drops slightly in cold weather.
- Bivalence point: this is where the lines intersect.
- To the left of this, a heating element or a second heat generator helps out.
A hybrid heating system consists of two heat generators with different energy sources that share the work. Experts also refer to this as bivalent operation. Usually, the heat pump takes over for most of the year, and the boiler kicks in on very cold days.
When this is useful
According to the klimaaktiv Wegweiser (guide), combining a heat pump and a boiler is a good solution if the heat emission system requires temperatures significantly above 40 °C. One example from the guide: if an air-to-water heat pump runs inefficiently on cold days due to the large temperature lift, an existing biomass boiler takes over. There are also appliances that combine a heat pump and a pellet boiler in a single system.
What you should consider
- Two heat generators also means two appliances that require space, maintenance and a well-coordinated control system.
- klimaaktiv mentions pellet boilers as a suitable solution if radiators require a flow temperature of over 55 °C. At such temperatures, it is worth getting independent energy advice before making a decision.
- Often, the required flow temperature can be lowered, for example by replacing individual radiators or carrying out insulation measures. In this case, a heat pump alone may be sufficient.
Whether and how hybrid solutions receive public subsidies changes constantly. You can find the current status under Förderungen (public subsidies). The cost comparison tool helps you compare running costs.
Related terms
Monovalent, monoenergetic, bivalentBivalence pointFlow temperatureLow-temperature radiators
Sources
- klimaaktiv Wegweiser zur guten Installation von Wärmepumpen (klimaaktiv Guide to Good Installation of Heat Pumps, BMK, 2020) (accessed on 4 October 2026)
- klimaaktiv: The right heating system. A guide for homeowners (BMK, 2024) (accessed on 4 October 2026)
- klimaaktiv: So läuft Ihre Wärmepumpe rund. Tipps für die Planung und Installation (klimaaktiv: How to Keep Your Heat Pump Running Smoothly. Tips for Planning and Installation, BMK, 2024) (accessed on 4 October 2026)