Split heat pumps are a type of air-to-water heat pumps that consist of an indoor and an outdoor unit, connected by refrigerant lines. These heat pumps can achieve water temperatures of up to 65°C and are often used in systems where higher temperatures are not required (underfloor heating and fan coil units). An advantage over monoblock heat pumps is that glycol (antifreeze) does not need to be added to the water, as all the water is inside the building and cannot freeze.

The indoor unit integrates control electronics, the heat exchanger, the circulation pump, an expansion tank, a safety valve, and a three-way valve for domestic hot water (DHW). This allows easy connection to existing systems without additional components. The heat pump enables users to combine a system for heating domestic hot water (for underfloor heating or radiators) with a system for heating and cooling spaces using fan coil units.

For the most economical energy utilization, new buildings incorporate two installations: underfloor heating for space heating and fan coil units for space cooling.