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A heated pool is a pool you’ll actually use
Let’s be honest about the British weather. Without heating, most outdoor pools in the UK only reach a comfortable swimming temperature for a few weeks each summer. Add the right swimming pool heating and that window stretches from spring right through to autumn.
The good news is there’s no single “best” option. The right choice depends on how you want to use your pool, when you want to swim and what matters most to you: upfront cost, running cost or speed.
In this guide we’ll walk you through the main heating options, what each one is good at, and the questions worth asking before you decide.
How swimming pool heating works
Every pool heater does the same basic job, whichever type you choose. Your filtration pump draws water from the pool, pushes it through the filter, then through the heater before it flows back in. The heater lifts the temperature a little on each pass, and a thermostat switches it off once the pool reaches the temperature you’ve set.
What changes from one system to the next is where the heat comes from. A heat pump takes it from the air. A boiler burns gas or oil. An electric heater uses an element, much like a kettle. Solar collects it from the sun. That difference is what drives the speed, running cost and carbon footprint of each option.
Because the heater works hand in hand with your pump and filter, it’s easier and cheaper to plan heating in at the design stage than to add it later. If you’re planning a new pool, it’s one of the first things we’ll talk through with you.
There are four main types of swimming pool heating
Here’s how the four options compare at a glance:
- Air source heat pump: low running costs and holds temperature well. Heats at a medium pace and works best when the air is above around 8°C. Medium upfront cost.
- Gas or oil boiler: heats fast in any weather and holds temperature well. Medium to high running costs, medium upfront cost.
- Electric heater: heats fast in any weather and is the cheapest to fit. The most expensive to run.
- Solar: almost free to run once fitted, but heats slowly and needs sun and warmth. Higher upfront cost.
Air source heat pumps: the most popular choice for UK pools
A heat pump pulls warmth from the outside air and transfers it into your pool water. Because it moves heat rather than creating it, a good unit can put out several times more heat energy than the electricity it uses. That’s why running costs stay low.
Heat pumps are at their best from spring to autumn, when the air is mild. They’re quiet, reliable and pair perfectly with a pool cover. The one thing to know is that they slow down as the air gets colder, so they’re not the fastest option in early spring or late autumn.
Best for: most outdoor pools used through the main swimming season.
Gas and oil boilers: fast heat whatever the weather
A dedicated boiler heats water quickly and doesn’t care what the weather is doing. If you want to warm the pool up fast for a weekend, or swim well into the colder months, a boiler delivers.
The trade-off is fuel cost and carbon. Boilers tend to cost more to run than a heat pump, so many owners use one as a backup rather than the main source.
Best for: fast heat-ups, cooler months and back-up heating.
Electric heaters: simple and cheap to fit
An electric heater is the simplest system to install and costs the least upfront. It heats quickly and holds temperature accurately.
The catch is running cost. Electric heating turns every unit of electricity into one unit of heat, so it’s far more expensive to run than a heat pump. It’s usually best kept for smaller pools, spas and swim spas.
Best for: small pools, spas and occasional use.
Solar heating: free warmth when the sun shines
Solar panels or collectors use the sun to warm your pool water. Once they’re fitted, the heat is free. Solar is a great way to cut running costs and your carbon footprint.
On its own, though, solar relies on sunny, warm days and heats slowly. Most UK pool owners use it alongside a heat pump or boiler rather than instead of one.
Best for: cutting running costs as part of a wider system.
Hybrid systems: the best of both
If you want to swim for as much of the year as possible, a hybrid system is worth a look. It pairs a low-cost main source, like a heat pump or solar, with a back-up boiler or electric heater. The system switches over automatically when the weather turns, so your pool stays warm without you lifting a finger.
If you already have a ground source heat pump, biomass boiler or other hot water system at home, it may also be possible to link it to your pool through a heat exchanger. Ask us and we’ll tell you if it’s an option.
Sizing your swimming pool heating correctly
A heater that’s too small will struggle to keep up, especially in spring and autumn, and will run for hours on end. One that’s too big costs more to buy than it needs to. Getting the size right is one of the most important parts of the job. If you’re still deciding how big your pool should be, our guide to swimming pool size is a good place to start.
When we size a system, we look at:
- The surface area and volume of your pool
- The temperature you like to swim at
- The months you want to use the pool
- How exposed your garden is to wind
- Whether the pool is covered when it’s not in use
- Where the heater will sit and how far it is from the pool
Wind makes a bigger difference than most people expect. A pool in an open, breezy spot loses heat far faster than one sheltered by walls, fences or planting. That can be the difference between one size of heat pump and the next.
We’ll always size your heating to your pool and your garden, not to a rule of thumb.
A good cover is the cheapest heater you’ll ever buy
Whichever system you choose, most of the heat a pool loses escapes from the surface, especially overnight and on windy days. A well-fitted cover traps that heat in, so your heating works less and your running costs drop.
Covers also keep leaves and debris out and cut down on evaporation, which means less topping up and fewer chemicals. Pair a heat pump with a good cover and you have one of the most cost-effective set-ups there is. Our guide to pool running costs explains where the rest of your budget goes.
Simple ways to get more from your swimming pool heating
A few easy habits will help your heating work less hard and keep your pool warmer for longer:
- Cover up every time. Put the cover on whenever the pool isn’t in use, especially overnight. It’s the single biggest saving you can make.
- Pick a temperature and stick with it. Letting the pool go cold and then reheating it takes longer and often costs more than holding a steady temperature.
- Shelter the pool from wind. Fencing, hedging or glass screens all help keep the heat where you want it.
- Run your heat pump when the air is warmest. Heat pumps work most efficiently in the middle of the day, so set your timer to make the most of it.
- Keep the filter clean. Good water flow through the heater means it can do its job properly.
- Book an annual service. A yearly check keeps your system running efficiently and catches small issues before they become big ones.
Where your swimming pool heating system will go
Heat pumps and boilers usually sit close to your pump and filter, often next to the plant room. A heat pump needs good airflow, so it’s normally placed outdoors on a solid, level base with space around it. Keep it away from bedroom windows and your neighbours’ boundaries where you can, as the fan does make some sound when it’s running.
Solar collectors need a sunny, south-facing spot, such as a roof or a frame in the garden. Boilers need a fuel supply and a flue, and electric heaters need a suitable power supply.
Air source heat pumps are often allowed without planning permission, but the rules depend on where you live and the size and position of the unit. We’ll help you check with your local council before any work starts.
Five questions to help you choose
- When do you want to swim? For spring to autumn, a heat pump is usually all you need. For year-round swimming, look at a hybrid system.
- How quickly do you need the pool warm? If you tend to heat it up for weekends or visitors, a boiler or electric heater gives you speed.
- What matters more, upfront cost or running cost? Electric is cheap to fit but costly to run. Heat pumps and solar cost more at the start and save you money every season after.
- Is your pool indoors or outdoors? Indoor pools lose less heat to the weather but need the room heated and ventilated too.
- How green do you want to be? Heat pumps and solar have a far lower carbon footprint than gas, oil or direct electric heating.
Not sure where you land? That’s exactly what we’re here for. We’ll look at your pool, your garden and how you want to use it, then recommend the system that makes sense for you.
Pool heating questions we get asked a lot
What’s the cheapest way to heat a swimming pool in the UK?
For most outdoor pools, an air source heat pump combined with a pool cover gives the lowest running costs across the season. Adding solar can cut costs further.
Can a heat pump heat my pool in winter?
Heat pumps slow down in cold weather, so they’re best suited to spring through autumn. If you want to swim in winter, a hybrid system with a back-up boiler or electric heater is the better choice.
What temperature should I heat my pool to?
Most families are happy between 26°C and 29°C. Every degree warmer adds to your running costs, so it’s worth finding the temperature that feels right and sticking to it.
How long does it take to heat a pool?
It depends on the size and depth of the pool, the heating system and the weather. A boiler or electric heater works quickest. A heat pump takes longer from cold but is very good at holding the temperature once it’s there.
Do I really need a pool cover?
We’d always recommend one. A cover keeps the heat in, keeps debris out and lowers your running costs, whichever heating system you choose.
Can I add heating to an existing pool?
In most cases, yes. A heat pump or solar system can usually be connected to your existing pump and filter. We’ll check your equipment and your space first to make sure it’s a good fit.
Are pool heat pumps noisy?
Modern heat pumps are much quieter than older models. You’ll hear a gentle fan when it’s running, a bit like an air conditioning unit. Placing it thoughtfully, away from seating areas and neighbours, makes a big difference.
How long does a pool heat pump last?
With an annual service and a cover on the pool to take some of the strain off, a good quality heat pump should give you many years of reliable heating.
Is swimming pool heating worth it?
If you want to swim for more than a few weeks a year, yes. Heating turns your pool from an occasional summer treat into something the whole family uses from spring to autumn, which makes the whole investment far better value.
Talk to HiLife about heating your pool
Choosing the right heating system is one of the best decisions you’ll make for your pool. Get it right and you’ll swim more, spend less and enjoy your garden for more of the year.
Our team will help you find the right fit for your pool and the way you like to swim. In the meantime, you can explore our full range of pools. Call us on 01483 323 676 or email hello@hilifepools.co.uk for a friendly, no-pressure chat, or get in touch online and we’ll come back to you.
