By the UK Pool Guide – Home Swimming Pools, Reviews & Advice Team · Updated May 2026 · Independent, reader-supported

How to Heat a Swimming Pool Cheaply in the UK – 7 Proven Methods

Heating a swimming pool through an English winter seems like an expensive luxury. Gas boilers can cost £10–15 per day to run, and electric heaters push the price even higher. But there are practical, affordable ways to maintain a comfortable water temperature without bankrupting yourself.

The key isn't finding one magic solution—it's combining methods that suit your pool size, budget, and how often you use it. Here are seven proven approaches, ranked roughly by upfront cost and running expense.

1. Solar Pool Covers

A solar cover is the single cheapest heating tool you can buy. A decent one costs £150–400 and cuts heat loss by up to 95 per cent when left on the pool. It works by trapping warmth that would otherwise evaporate away, especially effective on sunny days even in British spring and autumn.

Running cost: virtually nothing—it's passive.

The catch: you need decent sunlight to see real gains, and it does slow down water circulation slightly. On genuinely cloudy weeks, a cover mainly prevents heat loss rather than actively warming the pool. Still, combined with other methods, it's essential. Unroll it when the pool isn't in use, take it off for swimming.

2. Thermal Insulation and Pool Blankets

Before heating anything, stop unnecessary heat loss. Evaporation from a pool surface is enormous—a 4×8m pool loses around 1,500 litres of water per month in summer, taking heat with it.

A thermal pool blanket (different from a solar cover) is thicker, often opaque, and offers pure insulation. Costs run £200–600 depending on size. Combined with a solar cover, this is powerful: you're preventing energy waste before spending money to heat water.

Check walls and pipes too—older above-ground pools often have poor insulation. Adding foam padding around exposed pipework is cheap and effective.

3. Heat Pumps

Air-source heat pumps are growing popular for UK pools because they work even in winter, though less efficiently than in summer. A decent pool heat pump runs £1,500–4,000 installed.

Running cost: typically £3–6 per day in summer, £8–12 in winter (far lower than gas heaters).

They pull warmth from the air and transfer it to the water—essentially a reversed fridge. Coefficient of Performance (COP) matters: a 15 COP heat pump delivers 15kWh of heat per kWh of electricity used. Modern units hit 10–16 COP in mild conditions.

The trade-off: they're slower to heat a cold pool than gas heaters (takes days rather than hours) and perform worse below 5°C. But for consistent, ongoing heating at reasonable running costs, they're increasingly the best option.

4. Gas or Electric Heaters

Traditional pool heaters work fast but cost a lot to run. Gas units burn £10–15 daily; electric immersion heaters are £8–12 daily. Both are fine for occasional use or rapid heating before a party, not sustainable for weeks on end.

If you already have a boiler, a pool heat exchanger that diverts hot water from your system is cheaper to add (£300–800) and uses existing heating capacity. Running costs depend entirely on your boiler efficiency and fuel type.

5. Solar Panel Systems

A dedicated solar pool heating system—panels that circulate pool water through tubes heated by the sun—costs £2,000–5,000 installed. This is a longer-term investment.

Running cost: negligible once installed (occasional electricity for pumps).

Payback takes 5–7 years in the UK depending on pool size and usage. In summer, a solar system can raise pool temperature by 5–10°C. Come October through March, output drops sharply, so you'd likely pair it with a heat pump or boiler backup.

6. Heat Exchangers

If you have a hot tub, spa heater, or home heating system already, a plate heat exchanger (£200–600) lets that system warm your pool without buying a dedicated heater. Hot water from your boiler or hot tub runs through the exchanger, transferring warmth to the pool.

Running cost: essentially the cost of the underlying heating system you're already running.

This only works if you have a suitable existing heat source. It's brilliant for hybrid setups but useless if you're starting from scratch.

7. Passive Water Circulation and Timing

The simplest tactic: run your pool pump during peak sunlight hours (10am–4pm in summer), not at night. Circulating warm water keeps the whole pool at that temperature rather than letting heat settle unevenly.

Running cost: you're already paying for the pump.

Also, aim to heat the pool in spring (March–May) when days are long and nights still short, so you maintain temperature through summer rather than scrambling to heat cold water in July. Use smaller pools and shallow water early in the season—less volume to heat.

The Real Approach: Layering Methods

The cheapest pools run a combination:

• Solar cover always on when not swimming
• Heat pump set to maintain 26–28°C in summer (very efficient at low lifts)
• Passive circulation during daylight
• Gas boiler only for rapid weekend heating or emergency top-ups

This approach keeps running costs to £3–5 per day in summer and £6–8 in shoulder months.

Running costs vary widely depending on pool size (small above-ground pools use much less than 10×5m in-ground builds), climate, and target temperature. A detailed comparison of the best pool heating systems for your specific setup is worth reading before investing in equipment.

Start with a solar cover and thermal insulation—both pay for themselves within a season. Layer other methods based on your budget and how frequently you actually use the pool.