A gas pool heater uses natural gas (NG) or propane (LP) to heat your pool water. Gas heaters are the quickest way to heat your pool or spa. Pool ad spa gas heaters have a lower per-unit upfront cost than the pool heat pump, but gas heaters’ main drawback is their relative energy inefficiency compared to pool heat pumps.

Gas Pool Heater Specifications You Should Know

Gas Type: Natural Gas / Propane – The gas type used to fuel your heater. Check with your local utility or gas company to determine if your home has natural gas service.

Heat Exchange: Copper / Cupro-Nickel – Copper heat exchangers are ideal for traditional chlorine (tablet or liquid) pools. Copper’s heat transfer ability is unmatched but too fragile for salt pool applications. 

Heat exchangers made the copper and nickel alloy called cupronickel can be used in traditional chlorine or saltwater pools. Pool heaters using a cupronickel heat exchanger are often called Heavy Duty (HD) pool heaters. 

Ignition Type: Electronic / Millivolt – Electronic ignition gas heaters use a spark start ignitor similar to a spark state on a gas grill. Electronic gas heaters are now the standard for the pool industry. Millivolt ignition uses a standing pilot for ignition, like old gas stoves. These heaters are less common due to extinguished pilot light safety concerns.

Raypak RP2100 Digital Natural Gas Heater, 399,000 BTU, Cupro-Nickel Heat Exchanger – P-R406A-EN-X / Propane Version

Unsurprisingly, a Raypak tops our list of best pool heaters; they are the standard-bearer in pool heating. The RP2100 Series 406A, with a Cupronickel heater exchanger, features a simplified design unique to Raypak while packing a punch with its 399,000 BTU output. In addition, the cupronickel heat exchangers make this heater compatible with salt chlorine or traditional chlorine pools.

Customer Review - The heater is super quiet; I can't hear it over my VSP Pool Pump on High. The water heats up quickly; incoming water temp is convenient on screen. Installation was quick for Pool Guy, easy to reverse Headers and Electrical (come on the right side), and Gas is on the Left. One complaint is that for the P6 Connector for the Power (and all Molex Connectors that connect to the board), the plastic clips that lock the connector on the board are extremely fragile when prying to allow you to lift the connector up and off. I ended up breaking ours, but the connector still stayed snug down. As far as operation, works great. Has three modes with Individual Set Points. After you flip the power on, you can press mode button to Spa (has a set Point for maintain temp), hit mode again to Off, hit mode again to "pool" with another set point. Hit mode again to off. The diagnostics menu is also nice since it will read out Flame Strength, On-board Voltage and Error Codes so you can find a problem quickly. Didn't need this menu, but was very nice to have for self troubleshooters. 

Raypak RP2100 Digital Natural Gas Heater, 399,000 BTU, Copper Heat Exchanger – P-R406A-EN-C / Propane Version

This RP2100 is essentially the same model as the top choice, the only difference being this model uses the not-as-durable copper heat exchanger. However, this heater is still a great choice if you don’t currently have or plan to convert to saltwater. The heat transfer efficiency is also slightly better than the cupronickel models.

Customer Review - This is my 3rd heater in 12 years. However, the Raypak has been working for 4 years with no issues. This heats up faster than my two other Pentair's I replaced. Installs easily. Would highly recommend.

Raypak RP2100 Digital Natural Gas Heater, 266,000 BTU, Cupro-Nickel Heat Exchanger – P-R266A-EN-X / Propane Version

The 266,000 BTU Raypak RP2100 with Cupronickel heat exchanger is a versatile pool heater because it can be installed on small inground pools, most above ground pools, and even spas. In addition, the cupronickel heat exchanger is great at withstanding the usually harsher water chemistry and conditions in spa applications.

Customer Review - Just finished installing it this weekend. So far love it compared to my old Jandy Lite2. It's better built, and you can tell Raypak has built HVAC equipment for the installer. Easy access doors, no screws for the lid, simple interface, helpful manual explaining how to replace parts and troubleshoot, wiring is done while standing up, etc... The big buttons and easy to read lcd are also nice touches, along with the dark door to protect those things from the sun and the elements. Will it have problems at some point? Yes but Raypak seems like they'll be good to work on. BTW, I was able to get hold of someone on the phone who knew the answers to my technical questions.

Hayward Universal H-Series Heater, Low NOx, 400,000 BTU, Natural Gas, Cupro-Nickel Heat Exchanger – W3H400FDN / Propane Version

The Hayward Universal H-Series Low NOx heater is the Swiss army knife of pool heaters. The H-series comes standard with a Cupronickel heat exchanger, electronic ignition, and low emissions LowNOx rating, meaning it can be installed in all states, including California. 

And that’s not all!

The Universal H-series forced draft system ensures constant optimal airflow through the heater allowing it to be installed on applications at sea level up to elevations up to 10,000 feet. The Hayward H-Series 400k BTU geas heater truly is one size fits.

Customer Review - Installation took all of 30 minutes by plumber and electrician. Runs extremely quietly...very efficient, and heats my water 2 - 3 degrees per hour. Perfect! A must buy!

Hayward Universal H-Series Heater, Low NOx, 150,000 BTU, Natural Gas, Cupro-Nickel Heat Exchanger / Propane Version

Apart of the same model series as the H-series mentioned above, 400k BTU, the H-Series 150K BTU is suitable for small inground pools but a better candidate for above ground pools or large spas.

Honorable Mentions:

Pentair MasterTemp Heater 400,000 BTU, Natural Gas, Low NOx, Copper Heat Exchanger – EC-462028 / Propane Version

Solid Heater, mixes the force air combustion of the Universal H-series making it suitable for high altitude installation from 0-9,000 feet. The MasterTemp falls short of the H-Series, by only being equipped with a copper heat exchanger.

Raypak AVIA Digital Heater, 399,000 BTU Low NOx, WiFi Ready, Natural Gas – PR404AENC / Propane Version

The Raypak AVIA pool heater will make this list in the future. It’s excluded from this list because it’s only been on the market for a year or two. The Raypak AVIA debuted in 2022, and it features a Low NOx emissions rating and Wi-Fi connectivity making the heater controllable via Raypak’s Raymote app.

The AVIA is currently only available with a copper heat exchanger, but an extra heavy-duty NiTek heat exchanger is due to be released. NiTek is said to be NiTek is 300% more erosion resistant than copper and 200% more than cupronickel. 

It’s also a drop-in replacement for the Pentair MasterTemp and Jandy LXi pool heaters.