Generally, two kinds of heat pumps are installed:

• There is the in-house air source heat pump, which is completely integrated into the unit. It comes either with a two heat exchanger system for changeover between heating and cooling mode, or a four heat exchanger system for greater operational reliability.

• Alternatively, the air source heat pump with an outdoor unit and inverter technology, which directly supplies a changeover heat exchanger integrated into the supply air stream.

This integral air source heat pump utilises the exhaust airstream to discharge the condensing heat in cooling mode and the exhaust heat in heating mode. At the very minimum, the heat pump provides heating and cooling of the hygienic outdoor air required for conventionally heated interiors. Linking the air handling unit into the heating and cooling water network is not required in this case.