Heat pump cost: what decides the price of a heat pump system

Capacity and what it has to do

Capacity is sized from the home’s heat loss, plus hot water and any pool it will heat. A larger capacity costs more, so an accurate heat-loss calculation matters: oversizing wastes money, and undersizing leaves the backup heater doing the work.

A heat pump that heats the home, the hot water and the pool is one machine doing three jobs, which often makes it better value than three separate systems.

Cylinder, buffer tank and controls

For hot water, a heat pump needs an indirect cylinder with a large coil, sized for its lower water temperature, and usually an electric element for the regular high-temperature cycle that keeps Legionella away. Many systems also use a buffer tank to smooth its running. Weather compensation and room controls add a little to the cost and a lot to the efficiency.

Radiators or underfloor heating

Heat pumps work best at low water temperatures, which suits underfloor heating perfectly. With radiators, they need to be larger than for a boiler to give the same warmth. In a new build this is planned from the start; replacing a boiler with a heat pump in a home with small radiators may mean changing some of them.

Placement and electricity supply

The outdoor unit needs a spot with free airflow, a solid base and a short, insulated pipe run to the plant room. Roof or long pipe runs add work. Larger units may need a three-phase supply or a meter upgrade, which should be checked before choosing the model.