Gas Pool Heaters

A gas pool heater is the most popular method of heating salt water pools and spas because of the speed and fuel efficiency when heating pool water to a warm and inviting temperature. You will be able to create luxuriously warm water fast so you can swim into the night time hours or extend your pool season into the cooler months of the year. 

gas pool heater

Gas pool heaters are fuelled by either natural gas or liquid propane. Natural gas that's sourced from an underground municipal line is the most common and cost efficient but unfortunately it's not available for everyone. If you don't have the option of natural gas you may have to use a large propane holder or tank to fuel the heater.  

A gas pool heater heats pool water the same way a gas furnace heats air in a home. The gas is burned to create flame in a combustion chamber and as water passes through it, it's heated by the water-carrying tubes. This process of circulating pool water through the heater is carried out until the desired temperature is reached. We'll take a look at everything you need to know about gas heating including the best gas pool heaters on the market. 

Gas Pool Heater Features

Natural gas and propane pool heaters are more efficient and environmentally friendly than ever before. You can count on efficiency upwards of 95% in some gas pool heater brands including pilot-less technology that couldn't be found even a few years ago. It's now possible to have the fastest pool heating option at a fraction of the cost. 

Low NOx Emissions

We talk about efficiency a lot when it comes to gas pool heaters and emissions are a big part of it. A low NOx pool heater is designed to reduced nitrogen oxide emissions and run more efficiently. It will also heat your pool faster and cost less to operate. Low NOx heaters are required by law in some states and recommended for any pool owner in the United States, Canada and Australia. 

Digital Electronic Ignition 

The difference between electronic and millivolt igniters is substantial and it's good to know the difference if you are purchasing a new heating system or replacing an old one. It's very rare to find a millivolt piloted heater today because they weren't reliable, attracted critters, were difficult to control and aren't allowed in some municipalities because of their low efficiency. 

Millivolt starters were used in the past because they didn't require electric power, which meant they could be operated where electrical service wasn't present or it was very expensive. They utilized gas to ignite the burners and needed to constantly stay on to operate, which lead to a lot of wasted fuel.  

Electronic or pilot-less ignition systems require no pilot light and only use fuel when there is a need for heat. The elimination of the pilot light means you'll use less fuel and save money every season. In addition to the increased efficiency, digital electronic starters are more reliable, more accurate, easier to control and much better suited for pool automation systems

Natural Gas or Propane

There are two types of fuel that will operate a gas pool heater, natural gas and propane. Natural gas is by far the most common because it's cheaper than propane and is often used to heat homes. It's relatively easy for a gas fitter to run a separate out-of-sight gas line to a bbq or pool heater from the house to provide constant fuel when needed. 

On the other hand it's very rare to find a home that is fuelled by propane. This means that you will need to store propane in a large container or holding tank near the pool. This can be tedious and expensive to install and even unsightly to have a large propane tank next to the pool. In addition to having the propane tank refilled periodically, you can expect to pay up to 85% less for natural gas vs propane. 

Gas Pool Heater Pros and Cons

Let's take a look at the gas pool heater pros and cons so you can get a better idea of how it performs compared to other pool heaters on the market. There is no doubt that they are the fastest way to heat up a pool or hot tub but they do have some drawbacks that might make them less appealing to some owner's. 


  • Fastest time to heat speed
  • Easy to install and automate
  • Heats any size pool in any climate


  • Expensive to operate
  • Maintenance can be costly

Gas Pool Heater vs Pool Heat Pump

There are a two main differences when comparing pool heat pumps and gas pool heaters. A gas heater will heat up a pool in a few hours while a heat pump can take a few days. If you are in a hurry and want to create warm water temperatures for a party or an event, a gas heater is a better option. 

The cost to purchase gas and heat pump heaters is very similar but you might pay more for a quality heat pump for a large pool. A heat pump heater in general will last longer than a gas pool heater so it often offsets the slightly higher price tag. As far as operating costs, you can expect to pay $2-$8 per hour to operate a gas pool heater vs heat pump which costs under $1 per hour if you live in a warm climate.  

The bottom line is that a gas pool heater will heat up water faster but it will cost more to operate than a pool heat pump. If you live in a northern state or in Canada, an electric heat pump heater is often not recommended unless you only plan on using it when the air temperature is above 50℉ (10℃). 

Gas Pool Heater vs Solar Heater

When comparing a gas pool heater to a solar powered pool heater a big difference is that a gas heater will heat a pool up in hours while a solar heater can take several days. A solar heaters ability is limited if there is insufficient sunlight hours, the ambient temperature is too low or there is not enough space for adequate solar collector panels. 

A solar heater provides free heat every hour that the sun is shining while a gas heater requires burning fuels, that can be expensive. Many pool owners are choosing to use a gas pool heater in combination with a solar heater to reduce the monthly operating costs, energy consumption and extending the life of the gas heater. 

The initial cost of both heaters are comparable if purchasing a quality solar powered pool heater system. In general though, you will spend less on a solar heater than a gas pool heater. The installation of a solar heater can be costly but can also be done by a handy pool owner while a gas heater should be carried out by a qualified service technician. 

The last consideration when comparing a gas pool heater vs solar heater is that you may require a larger pump to achieve adequate flow through the additional plumbing, valves and solar collector panels. A variable speed pump with more horsepower is often needed to ensure proper circulation with a solar heating system.

pool heater comparisons

Gas Pool Heater Cost

The average cost to operate a gas pool heater will vary depending on where you live and even then the price of fuel fluctuates. You can expect to pay between $2-$3 per hour or $200-$600 per month to operate a natural gas pool heater and 2-5 times that if you are using propane. This monthly cost is a very rough estimate but important to plan for if you live in a cool climate or on a tight budget. 

The average price to purchase a gas heater ranges between $1,000-$3,000. The gas pool heater cost will depend on variables like; pool volume, heater size and heater brand. Also factor in the cost to install a gas pool heater that can range between $250 and $500. If you ever need repairs, it can be costly unless you troubleshoot a gas heater problem yourself. 

Gas Pool Heater Sizing

Gas pool heaters are rated by BTU or British Thermal Unit output which is the amount of energy transferred to heat energy. The US Department of Energy has regulated pool heaters to have an efficiency rating of at least 78%. An example is a heater that puts out 200,000 BTUs and has an 85% efficiency rating would produce 170,000 BTUs per hour.

All pool heaters have a BTU rating and will be listed prominently by the manufacturer. The BTU output is important in determining the size of heater required to heat your pool. The ideal rating is dependant on the surface area of your pool where the larger the surface area of your pool is the higher BTU output required. 

A tip when shopping for a heater is to consider a 10% higher BTU rating than required just to be sure you have adequate heating during times of higher demand and at the beginning and end of the season. If you purchase a larger heater you will heat your pool faster, use it less often and potentially increase the life of your heater.  

Gas Pool Heater Sizing Calculator

There are a couple quick calculations to figure out the amount of BTUs required to heat your pool. We will walk you through it and at the end you will know exactly what size of heater to purchase for your specific pool. The first thing you need to figure out is the surface area of your pool and this can be done by the simple equation below. 

  • Rectangular Pools:  Length x Width
  • Round Pools:  Radius x Radius x 3.14
  • Oval Pools:  ½ Length x ½ Width x 3.14


  • Rectangle Pool 15 ft x 30 ft = 15 x 30 = 450 square feet
  • Round Pool 20 ft wide = 10 x 10 x 3.14 = 314 square feet
  • Oval Pool 15 ft x 30 ft = 7.5 x 15 x 3.14 = 353 square feet

After you have used these calculations to figure out the surface area of your pool you can determine the approximate amount of BTUs required to heat your pool while also being as efficient as possible. This guide is a rough estimate and variances could be caused by actual temperature, wind speed, humidity or sunlight.

Surface Area

  • 200 sq ft
  • 400 sq ft
  • 600 sq ft
  • 800 sq ft
  • 1000 sq ft

BTU's to Increase Water 20℉ (11℃)

  • 55,000  BTU
  • 105,000  BTU
  • 160,000  BTU
  • 210,000  BTU
  • 265,000  BTU

A pool with a surface area of 450 square feet requires a heater with at least 130,000 BTUs of output. A 160,000 BTU heater with 85% efficiency (160,000 x .85 = 136,000) would be sufficient as a minimum to increase the temperature of a pool with 450 square feet of surface area by 20℉. This means that you will be able to keep the pool heated to a temperature 20℉ above the ambient air temperature at anytime. 

Best Gas Pool Heaters

We've put together a list of the top rated gas pool heaters on the market from the most reputable brands in pool heaters. This list is comprised of what we consider to be the best pool heaters based on product quality, performance, reviews and professional experience. These pool heater brands are backed by exceptional customer service and industry leading product warranties. 

The Hayward Universal H-Series pool and spa heater uses natural gas or propane and boasts state of the art low NOx emissions. It can keep just about any size pool heated with BTU ratings ranging from 150,000-500,000 BTU's. The Cupro nickel heat exchanger provides unmatched efficiency and reliability so you can count on years of worry free heating. 

The Pentair MasterTemp high performance eco-friendly gas pool heater is available in natural gas and propane burning models. The BTU ranges from 175,000-400,000 BTUs with numerous options in between so you can find one just right for your heatings needs. The sturdy outer shell will ensure the heater will last many years and the digital display makes using the heater a pleasant experience.  

Best Above Ground Pool Gas Heater

The Hayward H-Series Above Ground pool gas heater is arguably the best on the market. It operates on both natural gas and propane and has an electronic ignition for pilot-less lighting. It's rugged and designed to perform in all weather conditions. You can reduce heatings costs by installing an above ground solar heater to work in tandem with your gas heater.  

Gas Pool Heaters and Salt Water 

All of the best gas pool heaters manufactured today are made to withstand salt and corrosion with stainless steel and titanium heat exchangers that resists rust. It's still important that you keep your pool balanced including pH, chlorine and calcium hardness to prolong the life of the heater.

We do recommend that salt water pool owners use a sacrificial zinc anode as a cheap way to add assurance and peace of mind. A check valve is another great piece of hardware that should be placed between the heater and chlorine generator in your plumbing system. Visit our salt water pool conversion page for tons of helpful information about conversions including gas pool heater installations.

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