Pool heating basics: heat pumps, solar and season length
An unheated pool in a temperate climate is comfortable six weeks a year. Heating — done sensibly — turns that into five months.
5 min read
The heat pump is the default answer
Air-source heat pumps move heat from air to water at 4–6× the efficiency of direct electric heating, and they've become the standard for private pools. Sizing rule of thumb: about 0.3–0.4 kW of heating capacity per m³ of water for a covered pool in a temperate climate — our plan pages compute a suggested size for every pool.
Temperature is a budget dial
Every degree costs. 24 °C is sporty, 26–28 °C is family-comfortable, 30 °C is resort luxury with a resort bill. The affordable strategy: size the heat pump generously, run it at 26–27 °C, and cover the pool every night — the cover is worth more than the next size of heater.
Solar: free heat with caveats
Solar absorbers add free degrees when the sun shines — which is also when you need them least. They shine as season-stretchers in spring and autumn and as heat-pump helpers. Full solar-only heating needs a large collector area (50–100% of the pool's surface) and patience with cloudy weeks.
Frequently asked questions
- What size heat pump for an 8 × 4 m pool?
- Around 12–16 kW for a covered pool at 1.2–1.8 m depths in a temperate climate. Undersized pumps run constantly and still lose the shoulder season.
- What water temperature should I aim for?
- 26–28 °C for family swimming. Below 24 °C is training territory; above 29 °C costs steeply and encourages algae.
- Can I heat without a cover?
- You can, at roughly double the energy. A night cover is the single best heating investment.