- Description Air sourced heat pumps are the most energy efficient and cost-effective method of heating your pool or spa water. In fact, a PowerSmart heat pump will use around 75% less energy than a standard electric spa heater and 55% less energy than natural gas. This massive saving in electricity allows you to cost effectively extend the swimming season of your swimming pool or keep your non-SpaNET equipped spa or swim spa at temperature and ready to use all year round.