Semi-detached property, hosted by David

5kW air source heat pump supplies both heating and hot water.

Heating is through a combination of radiators and underfloor heating running at the same temperature in a single unzoned arrangement.

Hot water is stored in a Sunamp heat battery due to restricted space for a conventional cylinder.

We are very happy with the performance of the heat pump. It provides all our heating and hot water throughout the year without any problems.

The room thermostat is set to 20degC all year around and the control system looks after everything else. The weather compensation function means that the heat pump output increases as the weather gets colder to provide just enough heat to keep the house warm.

The low temperature heating system does take some getting used to - the radiators are warm rather than hot and the heating will run for up to 10 hours a day when it is really cold.

We schedule a hot water run for 14:00 each day when the outside air temperature is warmest and the heat battery is normally full after an hour. The Sunamp is equivalent to a 120 litre cylinder and will provide about 4 showers before needing recharging (we don't have a bath).

Our energy usage shows the heat pump uses approximately 720kWh a year for heating to generate 3000kWh of heat (420% efficiency).

Hot water generation also uses around 720kWh a year to produce 1600kWh (220% efficiency) and we have never had to use the immersion heater to supplement the heat pump, even in the depths of winter. The Sunamp is more expensive to run than a conventional hot water cylinder because it requires a 65degC flow, so this drops our efficiency.