The 6 Best Pool Heaters to Extend Your Swim Season in 2021

If you’re reading this article, you’re probably one of two types of folks:  you’re a meticulous planner looking to extend your swim season as painlessly as possible… or you’re starting to feel temperatures dropping, and you need to start warming your pool back up right now.

Most pool owners enjoy pool seasons that stretch for months. But unless your local temperature’s always warm and balmy -- an impossible dream for anyone outside South Florida and the tropical parts of the world -- that comfy pool season will eventually give way to the chill of winter.

Swimming pool heaters are the most common solution used by temperate-dwelling pool owners to extend their swim seasons. There are three main types of pool heaters:

• Solar pool heaters
• Gas or propane pool heaters
• Electric heat pumps

Many homeowners we've heard from -- roughly 95% -- choose electric heat pumps for their energy efficiency and reasonable lifetime cost of use. However, there are benefits to solar and gas pool heaters as well, which can offset their drawbacks in certain scenarios.

Solar pool heaters are the most environmentally friendly way to heat your pool… but they also tend to heat your pool’s water slower than gas heaters or electric heat pumps, and they require a lot of surface area to work properly.

Gas or propane pool heaters are the best choice for year-round swimming. They’ll heat water quickly and can work at any temperature. However, the cost to run these heaters can also add up quickly, particularly if you want a warm pool all the time in the wintertime.

Let’s look at some of the best and highest-rated pool heaters of all types.

We’ll evaluate these heaters by their initial cost, the pool size they’re compatible with, and some other important details you’ll want to know before taking the plunge on something you should expect to use for many years to come.

Best for above-ground pools: FibroPool FH120

• Price: $1,499
• Average customer review: 4.3 stars (get it on Amazon)
• Type: electric heat pump
• Maximum pool size: 7,500 gallons
• Heat output: 20,000 BTUs
• Dimensions: 36” long x 16” wide x 24” tall
• Weight: 74 pounds

The FibroPool FH-120 can plug into any 120-volt GFCI outlet to produce 20,000 BTUs, enough to heat 18’ round above-ground pools, 12’ x 24’ oval-shaped pools, or any other combination of dimensions with less than 7,500 total gallons of water capacity.

FibroPool claims it takes less than half an hour to install this heat pump, but that estimate probably assumes you have some basic knowledge of plumbing.

FibroPool claims a COP (coefficient of performance) of 4.81, meaning it outputs 4.81 times as much heat into your pool per dollar of electricity used. This number may vary depending on electricity costs in your area, but it’s a good baseline to assess the FH-120’s value and performance.

Reviews are generally positive -- one commenter from Buffalo hooked the FibroPool FH-120 up to a 10,000-gallon pool (no word on whether it was above-ground or not) and raised their water temperature from 61 degrees to 83 degrees in three days.

Another commenter claimed the cost to run the heat pump round the clock, for an average water temperature of 93 degrees (which seems a bit warm to me, but anyway…), was only $25 a month, which is pretty affordable for bathtub-temperature pool water.

Best for spas and tiny pools: EcoSmart Smart 11

• Price: $469
• Average customer review: 3.6 stars (get it on Amazon)
• Type: electric heat pump
• Maximum pool size: ~1,000 gallons
• Heat output: 10 gallons per minute heated (no BTU rating)
• Dimensions: 12” long x 4” wide x 9” tall
• Weight: 16 pounds

Got a spa, spool, or plunge pool in your backyard and don’t want a heater that’s too big and powerful for these smaller sizes? Try the EcoSmart Smart 11 electric heat pump.

Reviewers and professional respondents alike note its capacity to be somewhere in the range of 500-1,000 gallons, with one response claiming the EcoSmart can heat 900 gallons of water by 15 degrees in just three hours.

If you’ve got an even smaller aquatic space to warm up, you may want to consider the EcoSmart 5.5, which is specifically designed and marketed as a spa heater.

It costs about as much as the EcoSmart 11, but you’ll probably save some money on electricity usage over the long run. However, if you have a full-size pool, you might want to consider one of the other options on our list…

Best for smaller to midsized inground pools: FibroPool FH055

• Price: $1,929
• Average customer review: 4.3 stars (get it on Amazon)
• Type: electric heat pump
• Maximum pool size: 13,500 gallons
• Heat output: 55,000 BTUs
• Dimensions: 16” x 40” x 18”
• Weight: 110 pounds - 160 pounds

FibroPool’s maximum capacity is rated for “mild to humid climates” with an ideal target of 80% humidity and 80 degrees of ambient temperature.

It’s a great heat pump for Florida pools (and for those in other warm, damp places like the Gulf Coast or the Caribbean), but its actual capacity will decline as you move towards more northerly latitudes and colder temperatures. Use this heater with a pool no larger than 10,000 gallons and you should be quite pleased with the outcome.

FibroPool loves to tout its COP, and the FH055 trounces the FH120 in this regard. You can expect 5.92 times as much heat to flow into the pool for every dollar of electricity the heat pump uses.

Still shopping for a new pool, and unsure of which type of pool might be right for you? Take our Pool Type quiz and get answers in just a few clicks! Tap the button below to start:

Best for heating inground pools fast: Hayward H Series

• Price: $1,849 - $3,199
• Average customer review: 4.1 stars (get it on Amazon)
• Type: natural gas
• Maximum pool size: ~1,000 gallons
• Heat output: 150,000 - 400,000 BTUs
• Dimensions: 21” wide - 36” wide
• Weight: 110 pounds - 160 pounds

Hayward is a well-known name, as it’s one of the pool industry’s most popular suppliers.

The H Series of gas-powered pool heaters ranges from 150,000 BTUs (suitable for pools as large as 20’ by 20’, or 400 square feet of surface area) to the top-end 400,000 BTU model, which can heat pools with up to 1,200 square feet of surface area.

The entire H Series line boasts a thermal efficiency of about 83%, which means these heaters effectively convert 83% of their utilized gas power into warmer pool water.

However, several prominently featured reviews from recent years note that these gas pool heaters can break rather quickly, so you may want to dig a bit deeper before putting this (or any other) heater in your Amazon shopping cart.

Best eco-friendly modular heating solution: Smart Pool S601

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• Price: $289 (per panel)
• Average customer review: 4.0 stars (get it on Amazon)
• Type: solar
• Maximum pool size: 80 square feet (per panel)
• Heat output: not rated
• Dimensions: 4’ wide x 20’ long (per panel)

Solar pool heaters can require a lot of space -- commenters on this product have recommended having solar heaters at least 60% the size of your pool’s surface.

For example, a single four foot by 20 foot panel would effectively heat about 48 square feet of pool, or roughly the equivalent of a 6’ by 8’ cocktail pool or plunge pool.

Someone with an 18’ by 36’ pool commented positively on the ability of three interconnected Smart Pool panels (12’ by 20’) to heat their pool in upstate New York.

Smart Pool offers this handy table for assessing your needs:

• 1 panel / system = max pool size 12’ x 24’
• 2 panels / systems = max pool size 16’ x 32’
• 3 panels / systems = max pool size 18’ x 36’
• 4 panels / systems = max pool size 20’ x 40’

Solar heating is cost-effective, but it can be cumbersome.

Beyond the large space requirements -- you’ll probably need to use a good chunk of nearby roof to safely secure and utilize your heater panels -- solar heaters won’t work so well in overcast or inclement weather, and they may not be especially effective at heating your pool water once the ambient temperature starts getting nippy.

However, if your main concern is low ongoing costs and minimal environmental impact, these panels might be just what you need.

Most cost-efficient heater for inground pools: Hayward HeatPro 

• Price: $3,499 - $4,299
• Average customer review: 4.3 stars (get it on Amazon)
• Type: electric heat pump
• Maximum pool size: 15,000+ gallona
• Heat output: 95,000 BTUs - 140,000 BTUs
• Weight: 250+ pounds

Hayward makes all kinds of pool equipment, including electric heat pumps as well as gas and propane-powered pool heaters. The Hayward HeatPro comes in two sizes: a 95,000 BTU model for most standard pool sizes, and a 140,000 BTU model for supersized swimming pools.

Both models have a COP of 5.7, making them a good deal more efficient than the FibroPool FH120, and very nearly as efficient as the FibroPool FH055.

For larger pools, it’s quite an efficient bargain. However, the Hayward HeatPro trades off energy efficiency for compactness -- both models tip the scales at over 200 pounds, and they’ll probably require as much space as a central AC unit.

For machinery this complex and costly, you’ll probably be better served hiring a professional for installation, and you may want to construct a small enclosure for your heat pump, too.

Ready to extend your swim season this fall?

Swim season doesn’t need to end when the leaves start to fall. You can extend your usable pool time by several weeks in both spring and autumn with the right pool heater.

However, it’s important to choose one that suits your needs, fits your budget, and can be installed safely and securely for years of efficient operation.

Would you recommend a different pool heater? Is there a better choice for any of the categories we’ve used here? Let us know in the comments!

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