Skip to main content

Best pool heaters 2021

Best pool heaters 2021
(Image credit: ShutterStock)

The best pool heaters keep you swimming year-round. After all, nobody likes diving into a freezing cold pool, which is why we’ve rounded up the top gas and electric pool heaters on the market right now. Make use of one of these and when the temperature dips, you can still enjoy swimming. To help you decide which type of heater is right for your pool, think about how you’d like the device to be powered. 

At present, the best pool heaters come in three types: gas, electric and solar powered pool heaters. Gas heaters are usually more expensive and noisy, but they heat water quickly. Electric pool heaters are usually more environmentally friendly and quieter. Solar-powered pool heaters, of course, use the energy from the sun, which makes them eco friendly. Although, as is often the case with these types of heaters, they require long hours of sunlight to heat water. So consider how much sunlight your pool gets on a typical day before investing in this type of heater. 

As with the best pool alarms, we’d also suggest setting a budget on how much money you wish to spend on your pool heater. The best pool heaters vary in budget - some can cost thousands, but you can find more affordable options that still heat your pool to optimum temperatures. It all depends on what you want from your pool heater, how quickly you need to heat up your water, and how big your pool is. If you’re looking for other ways to relax in your home, don’t forget to check out guides to the best hot tubs and the best swim spas

1. Pentair 460737 MasterTemp: Best propane pool heater

Best pool heaters: Pentair 460737 MasterTemp

(Image credit: Pentair )

Pentair 460737 MasterTemp

The best energy efficient propane gas pool heater


Dimensions: 36 x 25 x 30-inches | Fuel type: Propane Gas | Weighs: 128 pounds

Reasons to Buy

Best-in-class energy efficiency
Low NOx emission
Digital display

Reasons to Avoid


This propane gas pool heater heats up quickly so you won’t have to wait around for hours before taking the plunge. It’s certified for low NOx emission and outperforms industry standards. It has a rotating digital display so it’s easy to view, and user-friendly indicator lights help make it easy to both operate and monitor performance. 

The tough, rustproof exterior is designed to withstand all weathers, extending its longevity. The compact design and quiet operation mean you can swim in peace – it hardly makes a sound, so it won’t intrude on your poolside enjoyment.

2. EcoSmart Smart Pool 18: Best electric pool heater

Best pool heaters: EcoSmart SMART POOL 18

(Image credit: EcoSmart )

EcoSmart Smart Pool 18: Best electric

The best electric, tankless water heater


Dimensions: 6 x 14 x 17-inches | Fuel type: Electric | Weighs: 24.5lb

Reasons to Buy

Digital temperature control

Reasons to Avoid

Complex to install

This differs from other electric pool heaters in so far as it’s an electric tankless heater. Instead of traditional pressure switch activation, the EcoSmart Smart Pool 18 uses flow sensor technology, which increases its reliability and longevity and also reduces the risk of elements burning out. 

The EcoSmart Smart Pool 18 electric pool heater has a digital temperature display and dial that lets you set your preferred water temperature in 1-degree increments. It can be used as an alternative to a heat pump or as a booster. It’s compact and lightweight, and it’s energy-efficient – no matter what the ambient temperature.

3. Hayward HeatPro HP21404T: Most economical pool heater

Best pool heaters: Hayward HeatPro HP21404T

(Image credit: Hayward)

Hayward HeatPro HP21404T

Save up to 80% on your pool operating costs


Dimensions: 32 x 43 x 40-inches | Fuel type: Electric | Weighs: 250 pounds

Reasons to Buy


Reasons to Avoid

Not as fast as a gas heater

This HeatPro electric heat pump is ideal if you’re looking for an electric pool heater that will allow you to extend your pool season. It uses the outside air together with a titanium heat exchanger and profiled fan blade to generate heat for a fraction of the cost of gas pool heaters. 

The manufacturers say you could save up to 80% on your pool operating costs. As well as being energy efficient, it’s also easy to install and quiet to run, so you can enjoy your pool and backyard without the intrusion associated with a noisy pool heater.

4. Hayward H-Series H250FDN: Best natural gas pool heater

Best pool heaters: Hayward H250FDP Universal H-Series 250,000

(Image credit: Hayward )

Hayward H-Series H250FDN

High performance natural gas pool heater with low NOx emissions


Dimensions: 29.5 x 24 x 25-inches | Fuel type: Natural gas | Weighs: 165lb

Reasons to Buy

Low NOx emissions
Salt water and chemical corrosion resistance

Reasons to Avoid


The Hayward H-Series H250FDN is an energy efficient, high performance natural gas pool heater. The hydraulic design reduces circulation pump run time. It’s an environmentally friendly option for a gas heater as it produces low NOx emissions. 

This heater has a standard cupro nickel heat exchanger and offers ultimate installation flexibility on new or existing equipment pads. The forced draft system moves air through the combustion chamber at a precise flow rate, eliminating the outside weather variables that can affect the performance of a gas pool heater.

5. SmartPool SunHeater S120U: Best solar pool heater

Best pool heaters: SunHeater S120U

(Image credit: SunHeater)

SmartPool SunHeater S120U

Heat your pool with the power of the sun


Dimensions: 120 x 27.5 x 16-inches | Fuel type: Solar | Weighs: 17.5lbs

Reasons to Buy

Easy to install 

Reasons to Avoid

Requires long hours of sunlight

If you’re looking for an eco-friendly, cost-effective way to heat your pool, we think this is it. The universal system is suitable for in-ground or above ground pools, and this solar pool heater could not be easier to install – it’s designed to be placed on your roof, ground or fence, and it works in conjunction with your existing pool pump. 

This solar pool heater captures heat from the sun’s rays and can raise the temperature of the water in your pool by 6-10 degrees Fahrenheit, adding weeks to your pool season.

Which type of pool heater should you choose?

Understanding how each type of pool heater works isn’t rocket science but a basic grasp of the logistics will help you choose the best heater for your pool. There are three main types of pool heaters; gas pool heaters, electric pool heaters (including heat pumps) and solar powered pool heaters. The difference between them is the power source they use, but this affects everything from the installation process to the running costs, as well as which climates they are appropriate for.

Gas pool heaters

A gas pool heater runs in a similar way to your home’s hot water heater – it burns natural gas or propane in a combustion chamber and transfers that heat to the water as it circulates through the heater. It has to be connected to a gas line through an underground gas pipe. This means that while the initial upfront cost may be lower than other types of pool heater, the installation costs are usually higher. And depending on the location of your nearest gas source, installation can even be prohibitively costly. 

In addition to the added installation cost, the ongoing running cost of a gas pool heater is higher. The price of gas, which fluctuates, will determine the exact ongoing cost of running a gas pool heater.

Gas pool heaters are more powerful than other types of pool heater, so they’re good for heating bigger pools that hold a large volume of water, and useful if you want to heat your pool in a hurry. They’re also ideal if you live in a cooler climate, or if you intend to heat the pool occasionally and for short periods. If you’re looking for an eco-friendly way to heat your pool, however, a gas pool heater is not the answer.

Solar Pool Heaters

A solar pool heater is the most planet-friendly way to heat your pool. Unlike other types of pool heater, solar pool heaters use natural energy sources, making them the most economical option. A solar pool heater uses solar collectors to transfer the thermal energy of the sun to the water in the pool. You place the solar collectors near to the pool pump, so the heat is transferred to the water as it’s pumped into the pool. Once you’ve installed a solar pool heater, you’ll have almost no maintenance costs and no monthly operating costs. Once the panels are in place, you can sit back and let the sun do its job.

A solar pool heater is very easy to install. They don’t need to be connected to any kind of energy outlet, so you won’t need to hire an installer. They work slowly compared to a gas pool heater, but once the pool reaches the desired temperature, it’s easy to keep it there – just remember to ensure that both your pool and the solar collectors get plenty of sunlight and aren’t located in a shaded area. This type of heater is best suited to warmer climates that get plenty of sun. If you want to use the pool at night without experiencing colder water, you may need to purchase a diverter, so factor in the additional cost of this.

Electric Pool Heaters

As you might expect, electric pool heaters are the most popular type of pool heater, and arguably the most efficient. As well as performing consistently year-round, an electric pool heater is the fastest way to heat your pool. You’ll obviously have monthly costs with an electric pool heater – factor in that your electricity bill will go up – but you’ll spend less per month if you go for an energy-efficient electric pool heater, compared to one that’s cheaper to buy but has higher running costs.

Electric heat pumps are more eco-friendly than gas pool heaters as they use the ambient temperature to heat the water. They don’t need to be connected to a gas line, so they're also easier to install than gas pool heaters. Electric heat pumps raise your pool’s temperature less quickly than gas pool heaters, but they can be kept running longer for less money, so they’re more cost-effective if you want to use your pool every day.


As we’ve explained, some models of pool heater rely on the ambient temperature or sunlight to heat the pool, so climate is a key factor in determining which pool heater is right for you. The climate also affects the energy requirements you need when calculating the power requirements for heating your pool.

What size pool heater should you get?

Whether you want a gas, electric or solar pool heater, choosing the correct size heater for your pool is important. Gas and electric heaters are measured in BTU, or British Thermal Units. That’s the amount of energy it takes to raise one pound of water by one degree. 

The more you have to raise the temperature by, the more energy you need. It’s worth checking out one of the helpful calculators online to help you calculate the BTU you need in a pool heater. Consult a pool pro for more specific guidance.