Without a good heating system, a swimming pool in the UK is uncomfortable to use for much of the year. The right heating system, properly specified, makes a pool genuinely enjoyable from April to October in an outdoor setting — and year-round in an indoor pool.

Air-source heat pumps are the most energy-efficient heating option for most outdoor swimming pools and represent the right choice for the majority of new-build residential pool projects.

Heat pumps work by extracting heat from the ambient air and transferring it to the pool water, typically achieving a coefficient of performance (COP) of 5:1 or higher in warm conditions — meaning that for every unit of electrical energy consumed, five or more units of heat are delivered to the pool. This makes them significantly more efficient than direct electric or gas heating.

Modern heat pumps are quiet, reliable and straightforward to operate. They are most effective when air temperatures are above 10°C, making them well-suited to the UK outdoor swimming season.

Gas boilers heat pool water more quickly than heat pumps and are less affected by ambient air temperature, making them capable of maintaining water temperature even in cooler conditions. They are a reasonable choice where the pool is used intermittently and quick heat-up times are important, or where a pool is used through colder periods of the year.

The running costs of a gas boiler are typically higher than a heat pump for equivalent heating output, and gas boilers have no long-term future as the UK moves away from gas for domestic heating. For new projects, a heat pump is generally preferable.

Solar thermal panels circulate pool water through collectors on a roof or ground-mounted array, using solar energy to add heat to the pool. In the right conditions — a south-facing roof or open ground area, and a pool used primarily in summer — solar thermal can provide useful supplementary heating and reduce heat pump running costs.

Solar thermal is rarely sufficient as a sole heating source for a UK outdoor pool, but can be a cost-effective addition to a heat pump system.

For most new-build outdoor pools, we recommend a quality air-source heat pump as the primary heating system, combined with a quality pool cover. This combination provides the best balance of running cost, efficiency and ease of use. We are happy to discuss the heating options in detail for your specific project.