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There are few things more enticing on a sweltering summer’s day than a refreshing dive into a cool pool. But let’s be honest: If the water is one degree under 75, no one is hopping in. It may seem revitalizing, but when you get the chills after just a couple of minutes in unheated water, it’s hard to enjoy your outdoor oasis.

That’s where a pool heater comes in. But you’ll need to find one that isn’t going to completely rack up your energy bill—and actually works in the environment you’re in. “Which one you choose is going to depend on the size of your pool, whether there’s a spa, the size of your gas meter, and the size of your gas line running from your gas meter to your equipment,” says Caleb Brown, owner of Living Water Pool Service

We tapped pool builders and contractors to find the best pool heaters that will keep things just chill enough. Read on to discover the right one for you.

Our Favorites

Best Overall: Pentair Master Temp Pool Heater Natural Gas

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Power source: Natural gas | Square footage heated: 4,000 | Heat output: 400,000 BTUs 

What we like:

  • Smart connectivity
  • Works in dry areas
  • Certified for low NOx emissions

Worth noting:

  • Expensive

Why we chose it: With smart features, you can make sure your pool’s temperature is just right before diving in.

This Pentair pool heater offers 400,000 BTU of natural gas heat, but it’s certified for low NOx emissions, making it one of the most eco-friendly options on our list. Smart features through the Pentair Automation Systems make it especially easy to monitor your pool’s current heat status, and there’s a flame-strength sensor to ensure optimal heater performance, too. The unit uses a copper heat exchanger that works well in harsher conditions, like low pH or heavy use, so you’ll always enjoy perfect pool temperatures. Plus if you live in a dry climate, this might be the one for you: Brown prefers using natural gas pool models because they work better in the California heat, where he does pool installations. “We don’t have enough humidity out here, and most of the other electric heaters need about 60 percent humidity to operate,” he says. 

Best Electric: Hayward HeatPro Heat Pump

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Power source: Electricity | Square footage heated: 3,000 | Heat output: 140,000 BTUs

What we like:

  • Compact
  • Energy efficient
  • Quiet

Worth noting:

  • Not as powerful as natural gas
  • Only works in humid areas

Why we chose it: This electric heater uses 80 percent less power than a natural gas heater, ideal for those with energy efficiency in mind.

If you live in a more humid area, an electric pool heater may be the right choice for you. This one from Hayward uses an energy-efficient titanium heat exchanger to quickly heat up the water to an ideal temperature, even in the chillier months. This can lower your operating cost up to 80 percent compared to natural gas heaters. And those who live by the sea and have damage from the salt air will be happy to know that it uses an ultra-gold corrosion-resistant evaporator fin to prevent damage. Plus the electronic temperature control is easy to use whenever you want to change the temperature.

Best Propane: Sta-Rite Max E Therm Pool Heaters

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Power source: Propane | Square footage heated: 4,000 | Heat output: 200,000 BTUs

What we like:

  • Easy to replace heat source
  • Lightweight
  • Rust-proof

Worth noting:

  • Slightly less powerful than natural gas

Why we chose it: The rounded shape of this heater is less obtrusive than some of the boxier models.

This is one of the lightest and least bulky heaters on the market, and while pool heaters aren’t exactly stylish, the rounded shape of this one makes it a little more streamlined. The circular top allows the six-position control panel to rotate 360 degrees for easy viewing and programming, and the exterior is rust-proof. The heater is available in either propane or natural gas options, and it’s certified for low NOx emissions, making it an eco-friendly choice. The best part? How quickly it can warm up a pool thanks to a precise mixture of fuel and air that ignites in the combustion chamber for zippy heating.

Best Tankless: EcoSmart Smart Pool 27 Electric Tankless Pool Heater

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Power source: Electricity | Gallons heated: 15,000 | Heat output: 27 KW

What we like:

  • Tankless
  • Energy efficient
  • Can be used as a booster

Worth noting:

  • Takes some time to heat up

Why we chose it: This tankless electric pool heater steadily heats up and maintains temperature for a perfect pool day. 

Rather than using the traditional pressure switch activation that gas heaters rely on, EcoSmart Pool Heaters use flow-sensor technology to efficiently heat up the water 1 to 1.5 degrees every hour. Although that sounds slow, once you reach your desired temperature, it’s quite easy to maintain. This unit also offers a digital thermostat control, making it easy to switch the temperature. And because of its tankless design, it can be used as a booster for your current pool heater rather than replacing an entire system.

Best Solar: SunHeater S120U Universal Solar Pool Heater 

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Power source: Solar | Square footage heated: 216 | Heat output: Dependent on sun 

What we like:

  • Green
  • Good for above ground pools
  • Affordable option

Worth noting:

  • May need multiple panels
  • Heating depends on sun

Why we chose it: This sun-dependent design is the best above ground pool heater, no expensive machine required.

While Brown doesn’t recommend using solar heaters for large in-ground pools, as they’re not powerful enough, they generally work well for smaller, above ground ones (though note that depending on the size of your pool, you may need multiple panels to heat it properly). Set the panels up on your roof or on the side of your pool, depending on where you get maximum sunlight; the heater connects with your current pump to warm the water as much as 15 degrees Fahrenheit. 

How We Chose These Products

No one wants to take a dip in a frigid pool. A pool heater ensures that the water is at your desired temperature, ideally between 77 and 82 degrees Fahrenheit. As much as a heated pool is a luxury, you also don’t want your energy bill to soar, so we kept efficiency top of mind when selecting our picks. To help narrow down our search, we contacted pool contractors, who shared what to look out for while on the hunt for the best pool heaters and which models they’ve installed again and again. From there, we picked pool heaters that are superior in heating speed and work in a variety of climates.

Our Shopping Checklist

Types of Heaters 

According to Brown, the most used pool heaters are natural gas, as they’re pretty energy efficient and don’t require a certain amount of humidity to operate. However, there are other options that may work well for your climate and pool size—just make sure you know what you’re getting into. “I’ve walked into situations where they expect [a pool heater to] do all this stuff that it’s not ever going to do, and they’re frustrated when it doesn’t,” Brown says. 

Gas: These heaters use either propane or natural gas to quickly and effectively heat the water in your pool to a set temperature. They’re particularly good for colder climates or areas that lack humidity because the thermal energy quickly heats even the chilliest of waters. But they can be quite pricey and require the continuous purchase of gas or propane, too. 

Electric: There are two main types of electric heaters: tankless and heat pump. Tankless models function as a direct-flow heater and heat the water with electricity as it passes through. The heat pump model won’t work well in cold weather, however, as it relies on the outside temperature to help warm the water and reverts the humidity back into the water. Both models are cheaper than gas heaters but also require the continuous use of electricity, which can be expensive over time.

Solar: While not very common, solar pool heaters use a black or very dark tubing installed outside the pool to absorb heat from the sun and pass the heat to the water through heating tubes. They do require sufficient sunlight, meaning they’re best for warmer climates and direct sun, and you’re not able to set an exact temperature. “The only problem with solar is they don’t generate enough electricity to heat,” Brown says. Because of this, a solar heater is not very consistent, but it could be an energy-efficient and affordable option to warm up a smaller above ground pool. 

Heating Power

Pool heaters are typically measured in British thermal units (BTUs) to show how effective they are at heating. The higher the number, the faster it can raise the temperature. For example, 1 BTU raises the temperature of 1 pound of water by 1 degree. However, this is also dependent on the outside climate as well as how large the pool is. Brown says that the most common heaters are either 400,000 or 260,000 BTUs. 

Installation and Maintenance

The installation of a pool heater isn’t your average DIY project, which is why Brown highly recommends calling in a professional to ensure everything is connected properly. But once in place, these machines should have a long warranty; you may only need to replace individual parts over time.

When it comes to maintenance, you’ll have to replenish the gas source for gas heaters, which can add up, especially if you’re not cognizant of how much heat you’re using. “In the wintertime, if you’re trying to keep your pool heated and it doesn’t have a cover on it, you could spend $1,000 a month on natural gas to maintain it,” Brown says. Heaters don’t typically require too much cleaning or replacement, as long as you keep the heat source fueled.

Ask Domino

Q: Maintaining a pool is expensive! What’s the most affordable way to heat one?

To make your pool more affordable to heat—and ensure it doesn’t lose heat either—you’re going to need to use a cover. “Anytime you can maintain water temperature by minimizing evaporation, that’s going to be your key,” Brown says. “Solar covers, electric covers, anything that covers the pool and retains heat loss is going to make the pool the most efficient from a heating standpoint.”

Brown has seen an increase in the use of electric pool covers in particular, a no-fuss way of making sure your pool is covered when it’s not in use.

Q: What’s the fastest way to heat up pool water? No chilly feet, please.

According to Brown, the fastest way to heat up a pool is with a gas heater, which is more powerful than an electric or solar heater. “The gas heaters are the fastest as far as the amount of heat retained, combustion, and efficiency are concerned,” he says.

Q: Does it matter if I turn my pool heater off at night?

If you choose to turn off your pool heater at night, Brown says your pool will only lose about 3 to 5 degrees of temperature—as long as it’s covered. He typically runs his pool heater from 8 a.m. to 8 p.m. When the pool pump turns on in the morning, the heater will continue heating and get up to temperature again.

The Last Word

While not required, a pool heater sure makes taking a dip so much more enjoyable and comfortable. For fast and efficient heating, a natural gas heater like the Pentair Master Temp Pool Heater is a great option for all types of climates. However, if you prefer an electric model and live in a humid climate, the Hayward HeatPro Heat Pump is another good choice.

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