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Best Pool Heater You Can Buy in 2020

The reason to purchase a heater should be obvious. When it gets cold outside, you may want to still go swimming in your pool. So, you need a heater to warm up the water and make it comfortable to be in there.

If you’re like most newbies, you probably don’t know where to start when it comes to purchasing a heater. After all, not all heaters are the same. In fact, there are three different types of heaters which will be discussed in this guide. These include pool heat pumps, solar heaters, and gas heaters. Below we’ll discuss how each type functions, their cost, choosing the appropriate size, advantages, disadvantages, and the cost savings of using a heater and cover on your pool.

It is worth mentioning that “British thermal units” are used to measure the size of a heater. In other words, when a heater generates a certain amount of heat, the measurement of this heat is a BTU. The general heat output range is between 75,000 and 450,000 BTUs.

Top Pool Heaters

Below is a list of the best swimming heaters available on the market. There are various features which make each one uniquely great. Some are more affordable while others are of better quality. We’ve provided you with enough information about these heaters to help you make the best choice.

Top Rated: The Best Choice for Swimming Pool Heaters

Our Score: 9.8/10

1. Hayward H400FDN Universal H-Series Pool Heater Gas

  • Heats quickly
  • Clear and accurate display
  • Heats to any temperature you want
  • Winterizing does not require any effort
  • 1 Year Limited Manufacture warranty

Learn More >>

On Amazon.com
Why we chose it

The Hayward H400FDN is the perfect heater for a big pool. It’s heating power goes up to 400,000 BTUs, which should be more than enough to heat any standard residential sized pool. The H400FDN design is like other Hayward product designs. This allows you to easily replace an older Hayward product that you may have already. Compatibility won’t be an issue.

The H400FDN produces few emissions and runs quite efficiently. Even though you’ll see an increase in your heating bill, it won’t be as much as it would be with other types of heating systems. Its digital panels can easily be used to quickly adjust settings, including the temperature settings of the pool water.

Our Score: 9.2/10

2. Pentair MasterTemp Natural Gas Model Pool Heater

  • Raises water temperature quickly
  • Small footprint
  • Accurate digital thermostat which rotates
  • Non-metal sheeted exterior makes it tough and rust resistant
  • After the installation, you have 60 days to register in order to get the warranty

Learn More >>

On Amazon.com
Why we chose it

This is great for heating most in-ground swimming pools. It starts up quickly without a pilot light, so the water warms quickly even when the temperature outside is cold. The digital display and indicator lights are easy to read. For this reason, you shouldn’t have trouble setting the most ideal water temperature for yourself.

Overall, it is an affordable heater which is durable and works fast to heat the water. If you can tolerate the small amount of noise it makes, then you shouldn’t mind this heater.

Advantages of a Pool Heater

Each type of heater has its own unique advantages, whether it’s a heat pump, electric heater, or gas heater. Let’s look at some benefits that are common.

Longer Swimming Season

It is expensive to purchase and maintain a swimming pool. The lifespan of a pool ranges from 3 to 15 years. And you won’t even be using the pool the entire year either. Due to the weather, only a few months per year will be suitable for swimming. As a result, you probably won’t get a lot out of a pool.

However, a heater can prolong the swimming season into the colder months because it heats up the temperature of the water. This may not be the case for the winter season, but it can sure make the water comfortable in the fall and spring. But if you only have a mild winter season where you live, then perhaps the heater can make the water comfortable all year long. If this is the case, then a heater and pool are definitely great investments.

Swim at Night

If you live in a tropical region where it is warm, then it might already be okay to swim at night. But if you live in a location where the water temperature decreases after the sun goes down, then you’ll need a heater to swim comfortably at night. This is helpful if you’re throwing a party or some other kind of gathering at night. Perhaps you want to swim early in the morning and get your workout over with before you start your day.

Beneficial to Your Health

If you swim in warm water, it is better for your overall health. It is also a great form of cardiovascular exercise, especially if you’re suffering from joint pains. On the other hand, if you swim in cold water, then it can cause negative symptoms for people with weak immune systems or arthritis sufferers.

A heater will warm up the water and make it more relaxing for your muscles and joints.

Types of Pool Heaters for Inground Pools

1) Solar Pool Heaters

Solar heaters may be the most expensive to purchase, but they’ll save you the most money in the long term. These heaters pump the pool water to the pool filter. While this is going on, some of the water goes through a series of “solar collectors” which causes it to warm up. Then it reenters the pool and circulates with the rest of the water.

There are two types of solar heaters available.

  • The unglazed collectors are solar heaters which use heavy-duty panels made of plastic or rubber and a UV light inhibitor.
  • The glazed collectors are solar heaters which use an aluminum plate with copper tubing and an iron-tempered glass cover.


You get more durability with glazed collectors, which is why they’re more expensive. But you do get freeze protection with both unglazed and glazed collectors. That way, cold weather won’t affect the heater.

The Cost of a Solar Heater

The total cost of a solar pool heating system is typically around $3,000 to $4,000. This price includes the installation cost too.

Choosing the Best Solar Heater Size

You need plenty of backyard space for a solar heater. The solar collector you choose should have a surface area that is equal to 75% or 100% of the swimming pool area, depending on the environment. For instance, if you live in a southern state in America and you have an inground swimming pool with the dimensions of 16’ x 32’, then the surface area of your solar collector needs to equal 100% of that square footage. In this case, it would be 512 square feet. But if you live in a northern state, then your solar collector’s surface only needs to equal 75% of the square footage of the pool. That would make it 384 square feet in this example.

The pool pump needs to be the appropriate size to accommodate the solar heating system. If you have an existing heater that you’re replacing, then you may need a bigger or stronger pump to allow the water to push through this new solar system.

  • Can last up to 20 years.
  • Free energy and inexpensive to maintain.
  • The energy savings outweigh the installation costs.
  • Environmentally friendly because of no air pollution
  • Heats pool fast in sunny and warm climates.
  • Must have direct sunlight shining on the heater. If not, then you need a heat pump or gas heater as a backup heat source.
  • Expensive installation.
  • Water heats slowly; the sun must be shining.
  • Consumes a lot of square footage in the backyard.
  • Ugly

Do your homework before purchasing a solar heater and hiring an installer. First, you must inspect your backyard and take measurements to see if the heater will even fit there. If you have a big pool, you need more square footage for the collector. If the collector and pool end up being far away from each other, you will need a bigger pump with additional horsepower.

Consider your surrounding environment too. Just do your own research and measurements before contacting a professional installer. If you need further assistance in determining whether your property is suitable for a solar heater, search on the internet, and you’ll find some helpful articles.

2) Gas Pool Heaters

Propane or natural gas is used as the fuel for a gas heater. As water enters the heater through a hot tube, the combustion chamber heats up the water. The water comes back out and goes into the swimming pool.

Liquid Propane vs. Natural Gas

The price and availability of different types of fuel in your area will determine which one you use. Fortunately, a liquid propane heater and natural gas heater cost the same amount.

If you use natural gas to heat your home, you can use it to heat your swimming pool as well. Otherwise, you can purchase and install one of those big propane tanks in your backyard. Just be prepared to have it refilled on a regular basis. You’ll be paying about 2.5 times more money for propane than you would for natural gas. It all depends on how much supply there is versus the demand for it.

Electric Ignition vs. Millivolt

Millivolt refers to having a tiny amount of gas to sustain the flame of a pilot light. That way, it can fire up whenever you need it to. An electric ignition generates a spark to light the burners, like what is done with a gas grill. To avoid the chances of a gas leak, it is better to use the electric ignition.

Gas Heaters: Normal vs. Low NOx Emissions

If your gas heater is “Low NOx,” then it doesn’t release too many emissions. In addition, Low NOx heaters heat the water faster and have more efficiency than your standard heaters.

Most importantly, Low NOx heaters satisfy the NOx Emissions standards that were established by the Texas Natural Resource Conservation Commission Code and the California South Coast Quality Air Management Commission. Therefore, anyone living in Texas or California must use a Low NOx gas heater for their swimming pool.

Additional Features
  • Single Thermostat vs. Dual Thermostat – Dual thermostats come with most gas heaters. You can use them to monitor the temperature of both the spa and pool. If you purchase a small heater, there is just one thermostat.
  • Wind Resistance – Try to find a heater that is designed to be wind resistant or has a forced draft system. Then you don’t need to worry about outside weather elements compromising the heat in your swimming pool.
Average Cost of a Heater

The average cost of a natural gas heater is anywhere from $300 to $600 monthly. The monthly cost of a propane heater is even more.

The newest gas heaters for inground pools can cost anywhere from $1,500 to $3,500. It all depends on the brand, size, and type of heater.

Choosing the Best Size

What is the square footage of your swimming pool’s surface area? You must figure this out before choosing a heater. Also, research the average temperature of the air in your location. Do this for the coldest month of the year. Now figure out what you want the temperature of your pool water to be.

The average temperature of your location for the coldest month gets subtracted from the desired temperature you want for the water. Once you do this calculation, you will know how much the temperature must rise. To find the square footage of the surface area of your pool, multiply the length and width of this area.

After you’ve made all these calculations, there is a formula that you can use to determine how many BTUs must come out of your heater.

The formula is Square Footage of Pool Area * Temperature rise * 12.

Let’s say you live in New Jersey and you own an in-ground swimming pool that is 16’ x 32’. If you don’t know what the average temperature is in your location, just visit the U.S. Climate Data website and you can find this information. In New Jersey, the average temperature in October is 65°F.

If you wanted your swimming pool water to always be 80°F, then you would calculate your temperature rise with this equation:

80°F – 65°F = 15°F in Temperature Rise

Going back to the BTU formula, this would be the equation:

512 square feet of surface area * 15 in temperature rise * 12 = the heater must produce 92,160 BTUs of heat for the water.

  • Inexpensive
  • Carbon emissions are low
  • Quickly heats water, regardless of outside temperature.
  • Expensive to operate
  • Needs gas
  • Not environmentally friendly
  • Without natural gas, you need to use an unattractive propane tank
  • Lifespan is roughly five years

BTU output determines the rating of a heat pump heater. The same applies to a gas heater too. But what makes heat pumps different is their amount of horsepower is also rated. The average size of a heat pump is 3.5 horsepower/75,000 BTUs, 5 horsepower/100,000 BTUs, and 6 horsepower/125,000 BTUs.

Choosing the Best Size

Don’t purchase a gas heater until you know how far away it will be installed from the gas meter. You may have correctly sized the heater, but that doesn’t mean the size of the gas line will be compatible with it. If you were to purchase a $2,000 heater under these circumstances, connecting a new gas line may cost you anywhere from $500 to $1,000. This means you’ll have more expense to deal with.

What to remember:

  • Figure out the distance between the gas meter and heater.
  • Figure out the size of the gas line
  • Determine whether power is available in the location where the heater is going.


If you know all this information before purchasing a heater, it will save you so much trouble and money.

3) Heat Pumps

Gas heaters can heat your pool water quickly. However, someone who is environmentally friendly won’t like the idea of using them. But you can always reduce the amount of gas used by trapping the heat in the water with a solar cover.

Pool water goes into your heat pump and passes through it. A fan inside of the pump blows outside air toward an evaporator coil which has liquid refrigerant in it. This is how heat is generated. The heat then gets absorbed by the refrigerant and converts into warm gas. Once the gas reaches the compressor, the heat increases and ends up reaching the condenser. The hot gas is added to the pool water by the condenser. Then the hot gas goes back into the condenser and passes through it. This is where it turns into a liquid again and then goes to the evaporator coil again. The process repeats itself.

The Cost

The initial cost of a pool heat pump is higher than the cost of a gas heater. However, pool heat pumps are less costly to run and maintain throughout the season. They also don’t go bad as fast as gas heaters do.

The starting price range of a pool heat pump is between $2,000 and $3,000. The more expensive ones are around $4,000 to $5,000.

The cost of operating the heat pump depends on your location. Warmer areas won’t be as costly to run a heat pump compared to colder areas. For instance, if you live in Florida and own an outdoor swimming pool, it costs $1,400 each year to keep the temperature of the water at 80°F. But if you place a solar cover on the pool, it only costs you $300.

For those who live in the northern states of America, it costs roughly $1,100 yearly to keep your outdoor pool water temperature at 80°F between the months of May and August. If you have a solar cover, it only costs $120.

Choosing the Best Heat Pump Size

BTU output determines the rating of a heat pump heater. The same applies to a gas heater too. But what makes heat pumps different is their amount of horsepower is also rated. The average size of a heat pump is 3.5 horsepower/75,000 BTUs, 5 horsepower/100,000 BTUs, and 6 horsepower/125,000 BTUs.

  • Lasts for up to 20 years.
  • Inexpensive to run
  • No gas emissions
  • Environmentally friendly
  • Renewable energy
  • The best alternative to a solar heater
  • 220-volt electrical outlet needed
  • Colder temperatures make it less effective
  • Slowly heats the water
  • Expensive initial price

Heat pumps are great if you’d rather not purchase a solar heater. Even though heat pumps cost more money initially, the long-term cost savings of operating the pump will make up for it. You should make your money back within two years.

Your home water can also be heated with a heat pump too. This can save you money on your normal indoor heating expenses.

Which Pool Heater is the Best for Your Pool?

The heater that is best for your swimming pool will depend on your location on the map and the heat source that your home has available.

  • Use a gas heater if you live in a northern state with natural gas access.
  • Use a heat pump if you live in a northern state without any natural gas access.
  • Use a solar heater or heat pump if you live in a southern state.


These various pool heating systems can be purchased anywhere, but some are better to use in certain places than others. That is why we’ve made these recommendations.

If you’re on a tight budget, then a pool heat pump and solar cover are recommended. This will cost you a bit of money initially but consider it a long-term investment that will save you money later.

Heater vs. Pump

Electricity is used to power both an electric heater and a pool heat pump. But these are different devices, though. Electric heaters use a hot coil to transfer heat to the pool water. Pool heat pumps transfer heat to pool water by taking the surrounding outside air and absorbing heat from it. Several components, including an air compressor, is used in a pool heat pump.

Pool heat pumps are initially more expensive than electric heaters. As for the monthly cost, pool heat pumps will save you up to 5 times the amount it would take to operate an electric or gas heater. Therefore, you’ll save more money as time goes on.

If pool heat pumps are installed and maintained properly, you can get at least ten years out of them. This is a lot longer than you could get out of electric or gas heaters.

It is cheaper to purchase an electric heater, but it’ll consume more electricity each month and raise your monthly power bill. But if you have an indoor spa, it can be used to heat that too. It all depends on what your specific needs are. In some cases, you might want to use both an electric heater and gas heater, especially for dealing with the cold winters or an indoor swimming pool.


We’ve presented you with some of the top-rated swimming heaters available. Of course, there are many other fabulous heaters available on the market too. The options available are almost endless. Our list has simply given you a place to start looking. Go through each one carefully and choose the best one which suits your needs.

Don’t let colder temperatures stop you from enjoying a nice and comfortable swim. A heater can make this dream come true.