The 9 Best Pool Heaters of 2021

Change the temperature of your pool without the hassle

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The Spruce / Chloe Jeong

Our Top Picks
This model is a low NOx pool heater that meets strict air quality standards.
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This model works for both inground and above ground pools, but you may need multiple panels to heat average to large pools.
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Skip the fuel supply if you choose an electric pool heater like this model for pools up to 15,000 gallons in size.
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Best Heat Pump:
Hayward HeatPro at Amazon
Less expensive than most gas pool heaters, a pool heat pump is a good alternative if you live in a warm weather climate.
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The all-weather cabinet features a poly-coated cabinet to protect the components inside from sun, wind, and rain.
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This model is affordable and ideal for smaller pools or light-duty heating in a warm climate.
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Smaller pools will benefit from this model that produces 125,000 BTU and boasts an 82 percent efficiency rating.
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A cupronickel heat exchanger is typically considered the best option for saltwater pools since it provides enhanced resistance to corrosion.
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Regulate the temperature of your pool with a 2-in-1 model that offers both heating and cooling functions.
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A pool heater means you can start swimming sooner and extend your season longer. These units work in tandem with your pool pump to warm pool water to a pre-set temperature and are compatible with both inground and above ground pools.

The type of pool heater you choose will depend on several factors, including the type and size of pool you have. More powerful pool heaters are typically required for large, inground pools. The gallons of water in your pool, along with how much you want the temperature to rise, will determine the BTU rating you should look for; residential pool heaters usually range from 100,000 to 400,000 BTU. The power source is also important, since you’ll need to decide between natural gas, propane, or electric powered pool heaters. 

Here, the best pool heaters to keep your water temperature constant for the whole swimming season.

Best Overall: Hayward W3H150FDN Universal H-Series 150,000 BTU Pool and Spa Heater, Natural Gas

Hayward W3H150FDN Universal H-Series 150,000 BTU Pool and Spa Heater, Natural Gas

Power Source: Natural gas 

BTU Output: 150,000 BTU

Pool Type: Inground

Pool Size: 450 square feet 

Raise your pool temperature and extend your swim season with the help of the Hayward Universal H-Series pool heater. Model W3H150FDN is a natural gas pool heater, which is often the most convenient choice for homeowners that already have a natural gas line installed. This 150,000 BTU heater is sized right for pools with an area of 450 square feet, which equates to about 13,000 gallons—depending on the specific shape and depth of your pool. However, the Hayward Universal H-Series is also available with increased heating power for larger pools.

One feature that makes Hayward pool heaters stand out is the use of cupronickel heat exchangers in all models. In comparison to copper heating elements that are more subject to corrosion, cupronickel is known for offering increased durability and longer life of service—despite exposure to pool chemicals, saltwater, and more. 

Best Solar: Smart Pool S601 Pool Solar Heaters

Smart Pool S601 Pool Solar Heaters

Power Source: Solar

BTU Output: Not Applicable

Pool Type: Inground or Aboveground

Pool Size: Varies

A solar pool heater is a great passive means of warming up your swimming pool. Instead of relying on gas, propane, or electricity, a solar panel heater absorbs energy from the sun’s rays. The solar heater then uses this energy to heat water passing through the panel from your pool pump. The warmer water is then returned to your pool. According to the manufacturer, you can expect to see the average temperature of your pool water increase by 6 to 10 degrees. 

With this explanation in mind, it’s easy to see that this is a great option for low-energy pool heating, but may not be the quickest way to heat a swimming pool. The number of solar panels you choose to install for your pool and the amount of sun received will play a big factor in determining whether or not this type of pool heater meets your expectations. 

The SmartPool Solar Heater includes a single panel array that is 4 feet x 20 feet. You can purchase and connect multiple solar panels to create a solar heater large enough for your swimming pool. While purchasing multiple panels, plus the necessary installation kit, may feel like an investment, it’s worth noting that you’ll incur no additional costs from gas or electricity when using this solar pool heater. 

Best Electric: Ecosmart US SMART POOL 27 Electric Tankless Pool Heater

Power Source: Electricity

BTU Output: Not applicable

Pool Type: Inground or Above ground

Pool Size: Up to 15,000 gallons

If you lack an existing natural gas line and don’t want the hassle of monitoring propane tank levels, an electric pool heater is another option to consider. The EcoSmart Pool 27 is a tankless pool heater that saves space while raising pool temperatures by 1 degree Fahrenheit every hour. A digital thermostat control gives you the ability to adjust the target temperature quickly and precisely.

Sized for pools up to 15,000 gallons, the EcoSmart Pool 27 uses a flow sensor to prevent element burnout. This is a 240V unit and it requires three 40 amp breakers for installation, so keep that in mind when determining whether or not you have the space required on the circuit board. While you won’t spend any money on gas or propane when using this electric pool heater, you can expect that it will cause an uptick in your energy usage. A big advantage of the EcoSmart Pool 27, though, is its price point. At less than $1,000, it’s significantly more affordable than many gas pool heaters on the market. 

Best Heat Pump: Hayward HeatPro W3HP21004T Pool Heat Pump

Power Source: Electric

BTU Output: 140,000

Pool Type: Inground or above ground

Pool Size: Varies

A heat pump is an alternative type of pool heater that uses ambient air to heat pool water. In warm climates, a heat pump is often more economical to operate than a gas pool heater or a conventional electric pool heater. The Hayward W3HP21004T is a popular choice that delivers up to 140,000 BTU and can meet the needs of heating an average to large swimming pool. 

Hayward designed the HeatPro series of pool heat pumps to be durable and quiet, especially in comparison with some gas pool heaters. For example, the stainless steel fan blade is profiled to improve airflow efficiency while also reducing the noise factor during operation. An acoustic compressor cover also helps to dampen noise produced by this pool heater. Since this type of pool heater is especially popular in warmer climates that often come with increased humidity, a corrosion-resistant evaporator fin and titanium heat exchanger helps to extend the service life of this pool heater. 

Best Gas: Raypak PR266AENC50 266,000 BTU Natural Gas Heater

Raypak PR266AENC50 266,000 BTU Natural Gas Heater

Power Source: Natural Gas

BTU Output: 266,000 

Pool Type: Inground

Pool Size: 25,000 gallons

This pool heater is fueled by gas, which is a convenient fuel source for many homeowners with an existing natural gas line. Raypak is a leading name in pool heaters. Model PR266AENC50 is equipped with features that make the heater easier to use while improving durability of the unit, such as digital electronic ignition.

A copper fin tube heat exchanger is typical for many gas pool heaters. However, Raypak adds an additional layer of protection against corrosion of rbis important component by adding a special component to the header, known as a ProTek shield. This module is intended to absorb corrosive materials before they reach the heat exchanger. As a result, it’s intended to break down over time, but is easy to replace and protects the heating element inside. In addition, this model is equipped with an electronic ignition that only fires when heat is needed. In comparison to a millivolt pool heater, which requires a pilot light to be lit at all times and burns fuel continually, the electronic ignition is more efficient and economical in terms of fuel consumption. however, this gas pool heater will need a nearby 120V or 240V power source

Best Budget: Raypak PR106AENC 105,000 BTU Heater

Raypak PR106AENC 105,000 BTU Heater

Power Source: Natural Gas

BTU Output: 105,000

Pool Type: Inground or above ground

Pool Size: Up to 10,000 gallons

A heated pool may feel like one of life’s luxuries, but it doesn’t have to be your biggest summer splurge if you shop for a budget pool heater. The Raypak PR106AENC is an affordable gas pool heater that offers 105,000 BTU to heat pools that hold up to 10,000 gallons of water. It’s compatible with both inground and above ground swimming pools. Raypak also makes this analog gas pool heater with increased BTU capacity for larger pools. 

This frills-free model includes an analog dial to set the target water temperature. Other pool heaters on the market often have an LCD display with digital temperature control, but this version relies on a turn-knob to adjust temperature settings. Inside the unit, Raypak has equipped this model to have a long life of service. Stainless steel burners and a copper-fin-tube heat exchanger are designed for durability despite wet working conditions.  

Best for Above-Ground Pools: Pentair MasterTemp 125 Low NOx Pool Heater

Pentair MasterTemp 125 Low NOx Pool Heater

Power Source: Natural Gas

BTU Output: 125,000

Pool Type: Inground or above ground

Pool Size: 15,000 gallons

Above ground pools don’t have the benefit of ground insulation, as is the case with inground pools. To keep pool water at an elevated temperature that makes swimming earlier or later in the season more pleasant, consider investing in an above ground pool heater.

Some inground pool heaters are too powerful for above ground pool set-ups. Save money and protect your pool from damage by choosing an above ground pool heater, like this model from Pentair. The MasterTemp series features natural gas or propane pool heaters that offer efficient, reliable heating for above ground pools. It has an 82 percent efficiency rating, meaning that only 18 percent of the energy produced is lost to the atmosphere and the rest is used to warm your pool. 

The Pentair MasterTemp 125 is a low NOx pool heater, making it eligible for installation even in areas with strict emissions guidelines. It plugs into a 120V electrical outlet and features electronic ignition to eliminate concerns of a standing pilot light. 

Best for Saltwater Pools: Raypak PR266AENX51 240,000 BTU Heater Electronic Ignition - NG

Raypak PR266AENX51 240,000 BTU Heater Electronic Ignition - NG

Power Source: Natural Gas

BTU Output: 300,000

Pool Type: Inground 

Pool Size: 25,000

Saltwater pools are known to take a toll on mechanical equipment and components, including a pool heater. However, you can minimize the potential for problems by choosing a pool heater specifically designed for saltwater pools. Most models have a copper fin tube heat exchanger, which can be negatively impacted when exposed to water from a saltwater pool. The best choice for these pools is a heater with a cupronickel heat exchanger. While the upfront cost is usually higher than a model with a copper heat exchanger, the payoff in terms of durability and service life makes sense for most pool owners. 

The Raypak PR336AENX51 is equipped with a cupronickel heat exchanger, along with Raypak’s ProTek shield that acts as a buffer against corrosion of your heat exchanger. The digital thermostat makes it easy to adjust the pool temperature to your preferences, and it can be tied into a remote system for convenient and automated control of your pool. 

Best Heater Chiller Combo: AquaCal SQ120R HeatWave SuperQuiet Pool Heat Pump

AquaCal SQ120R HeatWave SuperQuiet Pool Heat Pump

Power Source: Electric

BTU Output: Up to 110,000

Pool Type: Not Listed

Pool Size: 25,000 gallons

If you’re interested in extending your swimming season as long as possible, invest in a pool heater and chiller combo. This 2-in-1 pool heater from AquaCal is essentially a heat pump that uses warm air to raise pool temperatures, but it also has a module for cooling pool water using refrigerant. It can be used with both inground and above ground pools, but the manufacturer recommends that you choose a grid flow switch instead of a water pressure switch for above ground pool installation.

The AquaCal SQ120R stands out as a heater chiller combo for pools with smart features, like the ability to control the unit with the PoolSync app. Switch between heating and cooling modes or set the unit to keep your pool at a constant temperature with the Autotemp mode. You will need to buy a separate PoolSync WiFi Controller if you want to take advantage of this feature. 

In addition, this 2-in-1 pool heater is designed to withstand the elements. AquaCal has developed a special louvered top that allows for efficient airflow to the heat exchanger inside while minimizing the debris that enters the housing of the pool heater. A patented titanium heat exchanger is another standout feature of this pool heater and chiller combo. Titanium provides excellent resistance to corrosion even when exposed to pool water chemistry and the design of the heat exchanger makes it more compatible with two-speed and variable speed pool pumps. 

Final Verdict

Our top pick for pool heaters is the Hayward Universal H-Series W3H150FDN pool heater (view at Amazon), which comes standard with a cupronickel heat exchanger and can heat pools up to 13,000 gallons (or more if you choose a larger model in the Universal H-Series line-up). However, if you're looking for more control over pool water temperatures, opt for a heater-chiller combo like the AquaCal SQ120R (view at Amazon). This 2-in-1 pool heat pump can raise or cool the water temperature of pools up 25,000 gallons and is equipped with a long-lasting titanium heat exchanger.

What to Look For

Size

The size of your pool is a key factor to consider when picking a pool heater. The more gallons of water in your pool, the harder the pool heater will need to work to raise the water temperature. As expected, larger swimming pools will benefit from a pool heater with increased BTUs to more efficiently heat the water. 

Some manufacturers of pool heaters create a calculator that can help you to quickly and easily match your pool to the right size pool heater. For example, Raypak’s pool heater calculator uses your zip code, pool size, and swimming season months to help you compare energy costs when choosing different size pool heaters. 

BTU Output

Every pool heater will provide you with a BTU output rating. Most units range between 150,000 and 400,000 or more BTUs. A BTU (British Thermal Unit) is the measure of how much energy is required to raise the temperature of 1 pound of water by 1 degree Fahrenheit. You can approximate what type of BTU heater you need for your pool by multiplying your pool’s water capacity in gallons by the weight of a single gallon of water (8.6 pounds). The answer is how many BTUs you need to raise the pool water by 1 degree. 

Of course you’re probably looking for a larger rise in pool temperature than that, a few more calculations are needed. 

Determine the difference between your target pool temperature and the coldest ambient air temperature. For example, assume overnight air temperatures are 60 degrees Fahrenheit and you want your pool to reach 80 degrees Fahrenheit. This is a temperature difference of 20 degrees. 

Multiply how many BTUs are needed to raise your pool temperature 1 degree by the temperature difference. This is an approximation of the total BTUs that will be expended to raise your pool temperature. Divide by the time you expect your pool to reach target temperatures—often 24 hours, but it can be longer or shorter. Then, you have a rating of what BTU you should look for in a pool heater.

Keep in mind, though, that other factors like the use of a solar cover, the amount of direct sunlight received, rainfall, evaporation, and more can impact the performance of a pool heater. 

Solar vs. Gas

While gas pool heaters are popular for their superior efficiency, the biggest expense of operating these heaters is the natural gas or propane required for them to function. In addition, propane heaters may require tank refill or replacement regularly to ensure continued operation. 

Solar heaters eliminate the need for fuel altogether, since they use absorbed energy from the sun to raise the temperature of pool water. However, it can take longer to heat your pool using a solar pool heater, and the performance of this type of pool heater is directly dependent on the amount of sunlight received. This makes them a great choice for geographic areas with many sunny days, but a less efficient option in areas with more cloud cover. 

Pool Compatability

Most pool heaters are intended for heating inground pools. Some models are designed to also be used for heating above ground pools. However, it’s important to make sure that you are buying a pool heater that will be safe and effective for the type of swimming pool that you have. Otherwise, you may experience equipment malfunction or damage to your pool structure. 

If you have a saltwater pool, you’ll also need to consider whether or not the pool heater you’re considering is compatible. Technically, you can use any type of pool heater in a saltwater pool, but the heater may suffer from corrosion and impaired performance more quickly if it’s not intended for use in saltwater. This is because many pool heaters have copper heating elements inside. The salty water can eventually cause rusting of the interior components. A pool heater with a cupronickel heat exchanger is better protected against the corrosive nature of saltwater and is a better choice for this type of pool. 

Frequently Asked Questions

How long does it take to heat an average-sized pool? 

Many residential swimming pools hold between 10,000 and 20,000 gallons of water. How long it takes to heat this water will depend on a variety of factors, including how many degrees you want to raise the water temperature, the average ambient air temperature outside of the pool, whether you’re heating an inground or above ground pool, and what type of pool heater you choose to do the job. 

However, when you choose the right pool heater for the type and size of your swimming pool, you can often expect to hit target temperatures within 24 hours or less. It’s not uncommon for a gas pool heater to be able to raise temperatures by 5 degrees or more in less than 12 hours.  

How long can you expect a pool heater to last? 

Typically, pool heaters have a useful lifespan of 5 to 10 years. Heat exchangers are sometimes known for stretching this figure to 10 years or more. The corrosion from exposure to pool chemicals is one of the biggest factors that causes pool heater failure. 

How do you best maintain a pool heater? 

To maintain a gas pool heater, you should check the burner inputs for debris. Keep them clear of leaves, cobwebs, and accumulated dirt. If you have a propane pool heater, routinely check the tank gauge to ensure that you have enough propane for operation. For both propane and gas pool heaters, check the fuel lines for leaks. To do so, mix up some dish soap and water in a spray bottle. Apply the mixture to joints in the fuel line. If bubbles appear, you likely have a leak and repairs should be made right away.

For electric pool heaters, turn off the power supply and open the cabinet to safely remove the elements inside. Scrub any debris or corrosion with a wire brush to ensure optimal operation. 

With any type of pool heater, you should read the owner’s manual and take special note of any maintenance instructions specific to your system. Follow the steps for routine maintenance to ensure a long life of service from your pool heater. 

Why Trust The Spruce

This article was written by Erica Puisis, a home and lifestyle writer who has been researching the latest products for indoor and outdoor living for The Spruce since 2017. To compile this list, she considered a model's heating capacity, components, power source, and price, along with each manufacturer's reputation and reliability.

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