Monovalent, monoenergetic, bivalent

The operating mode indicates whether the heat pump heats alone, an immersion heater kicks in, or a second heating system such as a boiler assists.

You will often read one of these words in quotes and data sheets. They describe what generates the heat in your house.

Monovalent

The heat pump is the sole heat generator. It must cover the entire heating load on its own, even on the coldest day of the year. It must be sized accordingly for this.

Monoenergetic

The heat pump provides all the heat up to a specified output. If the house needs more, a second generator that also runs on electricity switches on: usually an immersion heater. Both then work together. The Bundesverband Wärmepumpe (German Heat Pump Association) explicitly advises against aiming for monovalent operation with air-to-water heat pumps. A slightly smaller unit with an immersion heater for peak loads cycles less frequently and operates more efficiently during the transitional periods.

Bivalent

Here, the heat pump works together with a heat generator that uses a different energy source, for example a pellet or wood boiler. klimaaktiv calls this combination a good solution if the radiators require temperatures well above 40 °C. On cold days when the heat pump would run inefficiently, the boiler then takes over.

Which operating mode suits your house depends on the heating load, flow temperature and existing heating system. Ask for the choice to be justified in the quote. You can find tips on this under Check quote.

All terms · Heat pump knowledge