Detailed Guide to Choosing and Using a Gas Pool Heater

In this article, we will discuss all gas pool heaters – how it functions, the pros and cons, and how it compares to other types of swimming pool heaters…

It is always bliss to swim in a warm swimming pool-relaxing and comforting whatever weather we may be experiencing. That is why many homeowners invest in a heater to warm and maintain their pool at the right temperature. 

Gas heaters have been one most used heating equipment in pools and spas. So in this guide, we will talk all about gas pool heaters-how it functions, the pros and cons, and how it compares to other types of swimming pool heaters. 

Knowing all of these can help you decide whether to invest in one or opt to buy other available options in the market.

Gas Pool Heater

How Do Gas Pool Heaters Work?

“I did then what I knew how to do. Now that I know better, I do better.” Maya Angelou, American poet. Just as the quote has said, you need to know more to do better. So to know whether gas heaters work for you, we first need to understand how it functions. 

A gas pool heater consists of four main parts:

Combustion Chamber

A confined space that ignites the natural gas fuel to release large amounts of heat. This chamber is connected to the gas heat exchanger.

Gas Heat Exchanger

An efficient heat transferring component that transfers the heat from combustion of the natural gas to the pool water. Usually, it has a large surface area to maximize heat transfer. 

Gas Vent or Chimney Stack

A tall structure where flue gases from the combustion escape to. A proper vent helps maintain the air supply inside the combustion chamber.

Pool Water Pump

It contains a moving part that circulates pool water into the gas heat exchanger. 

From its name, natural gas heaters use natural gas or propane as their main source of fuel. A pump draws in water from the pool and into the heat exchanger. The fuel burns in the combustion chamber that raises the temperature of the heat exchanger. Then the flowing water in the exchanger heats up and flows back into the swimming pool.

pool 5 feet

In the market, you may see some products like hybrid pool heaters that combine electric heat and gas heat to warm up a swimming pool or a spa. Although technically working under the same principle of heat exchange, there are some design and control differences. And that will be a topic for another guide.

Now that we know how a natural gas pool heater works let’s see how these translate into its advantages and disadvantages.

Advantages Of Using A Gas Pool Heater

Since gas pool heaters operate on the principle of combustion, the main advantage is the high heat rate. 

So if you need to heat a swimming pool in a short amount of time, a natural gas pool heater can be a great choice. It is also recommended for pool owners who want to use their swimming pools since it can easily maintain the desired pool temperature regardless of the weather.

Gas Pool Heaters operate on the principle of combustion.

Due to the simple operating parts of natural gas pool heaters, the equipment and its installation costs are lower than other types of pool heaters. Usually, the cost difference versus other types of swimming pool heaters ranges from $500 to $2000.

Disadvantages of Using a Gas Pool Heater

Although combustion gives it an advantage of a high heat rate, the main downside of natural gas pool heaters is their larger operating efficiency and costs.

According to the U.S Department of Energy, its heating efficiency ranges from 80% to 95%. [1] Although those heating efficiencies may seem high, every percentage can make a huge difference in the total annual operating costs.

Combustion also leads to a shorter lifespan of the equipment. Thus, a natural gas pool heater only has an average lifespan of 5 years as compared to other types of swimming pool heaters like the heat pump, which can last to 10 years.

Another downside is that combustion results in a negative impact on the environment. So if you’re very considerate of the environment, this type of pool heater might not be for you.

Gas Heater vs. Other Types of Heater

Now that we have an understanding of gas pool heaters. Let’s now compare it with other available pool heater types in the market. This will help you decide which pool heater works best for you.

You’ll find below a summary table comparing gas heaters with other pool heaters. These values are based on the data from the U.S. Department of Energy.

From the data you’ve read in the table, a gas heater works well if you have a large pool or if you want to have quick heating. Also, if you operate a spa, a gas heater may work well for you. Lastly, a gas pool heater might be for you if your location has cold temperatures throughout the year.

But if you want a higher efficiency or renewable energy as the source of pool heating, a heat pump or solar heater for you. Just be mindful of the operating conditions needed by each type.

Comparison Table

CategoryGas Heaters [1]Heat Pumps [2]Solar Heaters [3]
Heat SourceNatural gas or propane(non-renewable)Electric(non-renewable)Solar energy(renewable)
Heat CapacityLarge heat capacity(ranges from 75,000 BTU to 450,000 BTU)Medium heat capacity(ranges from 75,000 BTU to 125,000 BTU)Low heat capacity(ranges from 5,000 BTU to 100,000 BTU)
Heat RateFast heat rate; Can heat large pools to the ideal temperature in a few minutes.Medium heat rate;Can heat pools to the ideal temperature in 1 to 24 hours, depending on pool size and air temperature.Low heat rate; Can heat pools to the ideal temperature in a few days, depending on pool size and weather conditions.
Energy EfficiencyLow energy efficiency; 80% to 95%High energy efficiency; 300% to 700% Since renewable energy is free, it has a different measure for efficiency.
Operating ConditionsCan operate consistently regardless of the season and air temperature.Efficiency is dependent on the ambient air temperature.Since it operates on solar energy, it can’t work during the winter season.
Form FactorLarge form factor, depending on the heat capacity.Medium form factor, depending on the heat capacity.Requires a considerable surface area to maximize heat capacity.
Initial CostLow initial costHigh initial costHigh initial cost
Operational CostHigh operational cost;Dependent on gas cost.Low operational cost; But parts can be costly.Almost zero operational cost.

How to Select the Right Gas Heater?

If, after carefully considering all the comparisons above and you’re still making the choice of using gas pool heaters, it’s time to select the right gas heater.

It’s time to select the right gas heater.

You might wonder why we need to select the right gas heater. And the answer to that is cost-efficiency in both initial cost and operating cost. It does not make sense to pay for the heating capacity you won’t need, right?

So, to select the right pool heater, there are two things that we need to do: first, determine the pool heating needed, then size the gas pool heater. We will talk about that further below.

Although the steps below will teach you how to select the right gas heater, we recommend getting a professional service to select, install and maintain your gas heater.

Computing for Size of the Gas Pool Heater

The first step in determining the size of the gas pool heater is to decide on the water temperature that you want. Usually, the ideal water temperature sits around 85 to 95 degrees Fahrenheit. 

Then, take the average temperature of the coldest month that you use the pool. You can use a mobile weather app to help you get a record of the daily temperatures. Use Fahrenheit as the unit for temperature.

Next is to measure the surface area of your swimming pool. The unit to use should be in square feet so that it can be used in the standard formula for getting the pool heating in BTU per hour.

Use the standard formula below to get the BTU per hour rating:

[pool surface area (squared feet) x [ideal temperature (F) – coldest average temp (F)] x 12]

Example Computation – Gas Pool Heater Size 

Let’s say that you have a rectangular pool that measures 16 feet by 12 feet. You want to have a pool temperature of 90 Fahrenheit. And the average temperatures of the coldest month is 42 degrees Fahrenheit. 

Let’s input that into the formula:

[(16 feet x 12 feet) x (90 F – 42 F) x 12] = 110,592 BTU per hour

The next step is to get a catalog of gas pool heaters like Hayward and check the nearest but not lower than the computed size rating. 

As an example, if we look at the products of Hayward Universal H-Series [4], then the model that is the nearest but not lower than the computed size rating is the H150FD (rated at 150,000 BTU per hour.

Energy Saving Tip: Use a Pool Cover 

Using a pool cover is one of the best ways to reduce the operating costs of a swimming pool gas heater. It is a proven and efficient method in retaining the heat of pools. In fact, the U.S. Department of Energy recommends it to pool owners. [5].

Using a pool cover is one of the best ways to reduce the operating costs of a swimming pool gas heater.

So how does it work? Pool covers work by reducing water evaporation which is one of the larger factors of energy loss in a swimming pool. 

According to the U.S. Department of Energy, using a pool cover results in a 50 to 70 percent savings. Aside from energy loss, a pool blanket or cover can also lessen water consumption, chemical usage, and filter out dirt and debris.

Are you thinking of having a pool cover that is low-cost and yet effective? Click here to learn more about the best one for your home pool. 

What Are the Best Gas Heaters in the Market?

Due to the large selection of companies and the heater models they offer, it is difficult to pinpoint which is the best gas heater. Pool heaters from different brands have their own set of strengths and weaknesses. 

So does that mean that selecting any brand, model, or company is fine? 

The answer to that is no. Quoting Albert Einstein: “Any fool can know. The point is to understand.” 

Reflecting on those words, although there isn’t the best heater, we can research ways to get the best out of your pool heater. For example, get the brand or company with the most extensive service team and the most reputable customer support in your area. 

Do you have an Above Ground Pool in your home? Check this article, A Complete Guide for Heating an Above Ground Pool, surely it will guide you!

Gas Heater Brands

Below are the most reputable companies in the swimming pool industry. Each company model has its own strengths; research is the key to knowing each.

RayPak Gas Pool Heaters

A company that has been in the pool business since 1947. They’re well known for producing high-quality gas heaters. But they also have many models of heat pumps, water boilers, and water tanks.

Hayward Gas Pool Heaters

A company that has been in the pool business for 80 years. Aside from gas heaters, they have a wide array of product models of water pumps, heat pumps, water sanitizers, salt chlorinators, and filters.

Pentair Gas Pool Heaters

A company that has been in the water industry since 1966. They’re well known for their efficient water pumps and treatment, but they also produce good heat pumps, filters, and accessories.

Jandy Gas Pool Heaters

A swimming company that has been founded in 1958. Aside from heat pumps and gas heaters, they are reputable for their advanced pool automation.

Lochinvar Gas Pool Heaters

A water company that was founded in 1919. Today, they have a wide array of water heating solutions such as boilers, heat pumps, and pool heaters.

Generally, gas heaters can be ideal for a pool that requires a larger heating capacity and a fast heat rate. It is also the best for pool owners who want to keep their pool warm all the time despite cold ambient temperatures. A gas heater can also work best for spa owners.

Although a gas pool heater is less efficient than heat pumps, pool covers can cut operating costs. A right pool heater size can also lead to a cost-efficient operation.

For pool owners who are environmentalists, a gas heater might not be for you. You can instead opt to install a solar heater or a heat pump that has a lower carbon footprint.

  • [1] https://www.energy.gov/energysaver/gas-swimming-pool-heaters
  • [2] https://www.energy.gov/energysaver/heat-pump-swimming-pool-heaters
  • [3] https://www.energy.gov/energysaver/solar-swimming-pool-heaters
  • [4] https://hayward-pool-assets.com/assets/documents/pools/pdf/literature/Universal-H-Series-Brochure-LITUHS20B.pdf
  • [5] https://www.energy.gov/energysaver/swimming-pool-covers
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About the author

Ruben Anderson

I consider myself a pool and gadget geek. On thepoolpassion.com I review anything techie that helps me run a pool more effectively and efficiently.

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