How Pool Heaters Work and Create a Comfortable Swimming Experience


Pool heaters are one piece of equipment that is not absolutely necessary to have for your pool to run, but it sure makes it a lot nicer!  You have paid a lot for your pool; you want to make sure that you get as much use as possible.

Even in a warm climate like Texas, you want a pool that is refreshing and not frigid.

Of course, once you start looking into pool heaters, you will realize that the options are endless!  So many questions arise, such as:

  • What type of pool heater should I get?
  • What is the right temperature for my pool?
  • How do pool heaters work?
  • How much will it cost to buy?
  • How much will it cost to run?

pool heaters

Types of Pool Heaters

There are basically three types of pool heaters, distinguished by how they are powered.  They are: gas, solar and electric.

Pool heaters are sized by a measurement called “BTU” or British Thermal Unit.  This is the amount of heat required to raise one pound of water by one-degree Fahrenheit.

Solar Power Heater

Solar Power Heaters partially divert water from your filter into solar collectors.  The solar collectors will warm the water before returning it to your swimming pool.

There are two types of solar powered heaters: those with unglazed and glazed collectors.  Unglazed collectors are made of heavy-duty rubber or plastic; glazed are made with copper tubing on an aluminium plate.

How large should my heater be?

In a southern climate like Texas, your solar collector’s surface area should be 100% of your pool.  If your pool is 10 x 20, for example, your solar collectors should have a 200 sq. ft. of solar collectors.

How much does it cost? 

A solar powered heater will cost between $3,000 and $4,000 to buy and install.


  • Great for warm climates
  • Eco-Friendly
  • Efficient
  • You will save on energy, as it is inexpensive to operate
  • Lasts 15-20 years, if well-maintained.


  • You need a lot of direct sunlight
  • Large upfront cost
  • Heats the water slowly
  • Does not look attractive


Water is filtered through while a combustion chamber warms the water.  The warmed water is then returned to the pool.

There are many types of gas pool heaters. Gas pool heaters will use either natural gas or propane.

Gas pool heaters can be started with either a millivolt ignition, meaning a small pilot is always lit, or with an electronic ignition.

Low NOx gas heater is designed to release low emissions.  It is required in Texas, as it meets The Texas Natural Resource Conservation Commission Code.

What size gas heater should I get?

This calculation is a little more complicated than solar heaters.  You will need to know the square footage of your pool, the average temperature where you are and what you would like your pool temperature to be.

You would use this formula:

[square footage of your pool] x [ideal pool temperature minus average temperature] x 12

By way of example, imagine you have a pool that is 200 sq. ft.  The average temperature in Texas is 74 degrees Fahrenheit and let us assume you want your pool to be 82 degrees Fahrenheit.

Therefore, your formula would be:

200 x (82-74) x 12 = 19,200

Your gas pool heater would need to be at least 19,200 BTU to heat your pool efficiently.

How much does a new gas heater cost?

A new gas heater costs between $1,500 and $3,500 to buy and install.


  • Heats the water quickly
  • Low Emissions
  • Inexpensive to buy


  • Uses gas
  • Expensive to operate (between $300 and $600 per month)
  • Not eco-friendly
  • Lifespan of only five years


Water goes through a heat pump, which takes air from outside and heats it using an evaporator coil.

The gas that is created is moved to a compressor, the heat is increased and then heads to a condensor.  The hot gas that is in the condensor is added to your pool water to heat it.

The cost to run an electric heat pump will vary depending on the energy prices where you live. Of course, it will cost less the warmer your climate.

It has been estimated that to heat a pool using an electric heat pump for a year will cost between $760 and $1,240 in Texas.

What size should I get? 

Electric heat pumps are rated by BTU, like gas pumps, but also by horsepower (hp).  Standard sizes include:

  • 3.5 hp/75,000 BTU
  • 5 hp/100,000 BTU
  • 6 hp/125,000 BTU

You will perform the same calculation as above to determine the minimum BTU you need for your pool heater.

How much will they cost? 

There is a wide range here.  Electric heat pumps can cost anywhere from $2,000 and $5,000.


  • Eco-friendly
  • No emissions
  • Works well in low-sun areas
  • Inexpensive to run
  • Has a 20-year lifespan


  • Does not work well in colder temperatures
  • Higher initial cost to buy and install
  • Heats the pool slowly

Maximizing Your Pool Heater’s Performance

There are many ways that you can complement your pool heater to keep your pool warmer.  Some of these are choices that are made when designing your pool, and others can be factored in at any time.

Pool Insulation

If your pool is well-insulated, it will retain heat longer. The average ground temperature is quite a bit cooler so having your pool well-insulated will prevent your pool from being affected by those lower ground temperatures.

Pool Location 

Where is your pool located in your yard? Is it covered in shade, or does it get plenty of sunlight?

Is your pool sheltered from the wind? Wind causes the water to move which causes faster heat loss.

The answer to those questions will affect how long your pool stays heated.  You will want your pool in an area that gets the most sunlight and is shielded from the wind.

Solar Pool Cover

We recommend using a solar pool cover in conjunction with one of the above methods.  This is especially the case if you generally are not home during the day.

A solar pool cover uses the sun’s energy to heat the pool.

Additionally, it allows the pool to stay warmer longer, meaning your heater does not need to be used as often. Using a pool cover can limit heat loss by 50%!

Pool Color

You probably remember this from grade-school: dark colours attract more sun.  Consider choosing a darker coloured vinyl lining or tile for your pool to take advantage of that principle.

Choosing the Right Pool Heater

There are several factors that you will need to consider before choosing a pool heater. Think about your local weather, your backyard setup, and the power sources available to you.

As well, you will want to look at your budget.  This means looking at how much it will cost to buy, but also how much it will cost to operate monthly.

As well, some pool heaters look better than others.  For example, solar powered pumps are not aesthetically pleasing with all the solar cannisters.

Think about how your pool heater will play into the rest of your landscaping design and if there are ways to cover the less pleasing aspects of a pool heater’s appearance.

A note about saltwater pools: Salt water is very corrosive.  Pool heaters used for a saltwater pool will need to be fitted with a special heat exchanger and other features to be able to handle it.

You will definitely want to talk to your local pool professional about your saltwater pool and let them recommend suitable heating options.

pool heaters

What is the Right Temperature?

The first thing we think of with pool temperature is comfort.  It is really about finding a balance.

It is fun to swim into a cool swimming pool at a refreshing temperature – not one so cold that it is a shock!  It is also not ideal to jump into a warm pool on a hot day.

Ideally, your pool temperature is between 78- and 82-degrees Fahrenheit.  There are different groups you need to consider though to be safe.

The Red Cross recommends a pool temperature of at least 84 degrees Fahrenheit for children’s swimming lessons. This is to keep their little bodies comfortable and prevent difficulty breathing that can happen sometimes in cold water.

On the other end of the spectrum, our bodies become less tolerant of temperature changes as we age.  For elderly users, consider a temperature of between 84- and 88-degrees Fahrenheit.

If you are using your pool for exercise or therapy, you will also want to keep your pool a little on the warmer side (at least 84 degrees).

Installation and Maintenance

You can add a pool heater any time – even after the pool is built!  It is best to have a pool professional involved when installing pool heaters, especially if it is gas or electric.

Read your manufacturer’s manual to learn how to maintain this piece of equipment. At the very least, you will want to inspect it on a regular basis and have it tuned up by a professional on an annual basis.

Of course, maintaining your pool heater will ensure that it lasts longer.  We are always more than happy to talk to you about your equipment and help you with any of your pool cleaning and maintenance needs.

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