Pool Heaven's Pool School

Swimming Pool Heater

The swimming pool pump will pump pool water through the swimming pool filter.That filtered pool water will then pump through the swimming pool heater. When turned on, the swimming pool heater will open up the main burners where gas will combust and heat up filtered pool water inside the heat exchanger plumbing. 

This filtered, heated water will return to the pool and diffuse the heat throughout the pool until the pool water changes to the desired temperature set on the swimming pool heater. The heater will then close the main burner valve and stop the combustion until the pool water temperature drops under the set temperature when the pool heater would combust again.



The swimming pool heater has changed quite a bit this past 20 years. Many areas have high air standard regulations now and Low NOx pool heaters are the answer. Older pool heaters were mechanical with dials and they were pretty basic. They lasted longer, had fewer problems, and were just about as gas efficient as pool heaters today. Modern pool heaters have lower toxic emissions, digital displays, and stay cooler than older designs, so they are much better for pvc piping.

The modern Lo NOx swimming pool heater has more parts including electronics, computer boards, fans, etc. Computer boards in an outdoor setting provide for many of the repairs we see in the field. You can expect more expensive repairs, shorter lifespans, and more parts needing replacement over time. Innovation has a cost and there is no way to sugar coat this. That said, we don’t need copper plumbing anymore and our air is cleaner.

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Swimming pool heater repairs involve troubleshooting and can get costly. Computer parts in an outdoor setting, electronics, fans and blowers, and more parts and features than older heater designs demand more repair. Read more in our pool heater repair section.

Automation has made heating pools and spas very convenient. You can turn your heater on from a cell phone, indoor panel, or remote control today. There is no excuse for people to not be enjoying their swimming pools and spas. The modern swimming pool heater synchronizes with pool control automation for an enhanced swimming pool experience. Keep in mind that this automation also calls for more repairs for electronic valves, computer boards, relays, switches, and sensors. 


Salt water pools have added a curve ball to the game as well. Salt water can be corrosive to metal, so there have been some issues with copper heat exchangers and the Hayward swimming pool heater comes stock with a cupron nickel plated heater exchanger which is more durable. You can purchase this upgrade with the Raypak heater which is probably our favorite heater to install. 

There are several things to consider when choosing the right swimming pool heater for your pool or spa. You can read our article about which pool heater is best for you. Find out which brand of swimming pool heater is the best fit for your pool or spa.

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To say that a modern LoNox swimming pool heater can be challenging and expensive to repair could be an understatement. Can of worms is a phrase we use whenever we describe the discovery process in repairing a swimming pool heater. Modern LoNox pool heaters went through a dynamic change more than a decade ago which led to several innovations such as less toxic emissions, internal cooling systems, and digital readouts that synchronize with indoor control systems for convenient automation. You can turn your spa on and heat it up to 100 degrees without leaving your house now, but there is always a cost! Let us now consider what the best swimming pool heater is?

With Innovation Comes Challenge!

best pool heaterThese innovations were made possible due to the addition of computer boards, fans, motors, and other expensive mechanisms. With innovation comes challenge, so there were plenty of bugs and issues that all of the heater manufacturers experienced and are still experiencing. I will share our experience with the good, the bad, and the ugly when it comes to how the popular pool heaters stack up to each other.

There are three popular swimming pool heaters that our pool cleaning service in Irvine has experience with, so lets dive in. They are the Raypak P-R407A Digital LoNox Swimming Pool Heater, The Hayward H-Universal LoNox H400FDN Swimming Pool Heater, and the Pentair 460736 Master Temp LoNox Swimming Pool Heater. Let us start with the company that pre-dominantly specializes in boilers and heaters.

Raypak Swimming Pool Heater Is A Well Built Legend!

Raypak has been the authority in swimming pool heaters for over 50 years. Every once in a while, our pool cleaning service in Irvine will come across a working Raypak Pool Heater from the 60’s which is proof of how well built their pool heaters are. Raypak focuses on heaters and boilers unlike the other pool equipment manufacturers who also build pumps, filters, salt systems, etc. etc. Some say this specializing is what makes them better!

The older Raypak RP-2100 had a few bugs along with the other heater makers. Specifically, The temperature control board needed replacing prematurely on several of our installs and we had several cases of noxious, fumey gas that came from blocked up heater injectors and burner tubes from spider webs. Raypak changed a few things and have worked out some of their bugs, but all the heaters have very sensitive gas composition issues and will have challenges with blocked injectors and burner tubes due to demand for more gas with a LoNox Pool Heater.

You can expect fewer problems from a Raypak LoNox Pool Heater than from the other pool heaters from our pool cleaning service experience, but this does come at a premium as Raypak does make the most expensive, pool heater! It also comes stock with a copper heat exchanger which is fine unless you have a salt water pool or a heavily used hot spa in which case you would want to upgrade to a cupro-nickel plated heat exchanger to better protect your pool heater from corrosion and erosion. This upgrade could cost $300 to $500 extra with the Raypak and this needs to be considered.

Hayward LoNox Universal-H Pool Heater Is Good For Salt Pools and Hot spas!

Hayward has changed their pool heater design a couple times in this last decade, but has come up with a pretty decent, factory tested pool heater that is competitively priced. The major benefit of this Hayward Universal-H-400FDN pool heater is it comes stock with the cupron-nickel plated heat exchanger which makes it attractive for a salt pool or a heavily used spa. This means that you can expect to pay around $300 to $500 less than the Raypak which has to be upgraded to the cupron-nickel heat exchanger.

We have seen more pre-mature repairs on Hayward’s temperature control pad and computer boards than with Raypak and these can be expensive repairs (up to $800 or so). You also need to make sure and measure that you have enough room for the clearance of this Hayward Universal-H Pool Heater, because it has an awkward, low, and wide shape which leads me to the major benefit of our next pool heater.

Pentair LoNox Master Temp Pool Heater is Light and Compact!

You will get the lightest and smallest pool heater I have ever seen in the Pentair 460736 Master Temp Pool Heater. This heater makes for easier installs when it comes to tight spaces and walls that maybe need lifting over.

At 84%, this heater also rates highest in energy efficiency with the others only slightly less. The difference in energy efficiency is not huge, so it is not enough to gain much favor from us, yet. Like the others, this heater has had it’s share of bugs and issues as well.

Pentair has changed the design of their heater several times this past 16 years, but this appears to be a keeper for now! We have noticed some issues with using this pool heater with large sized pumps. Installers need to be aware of the tolerance of water flow within the heat exchanger for all the pool heaters, but especially this one from our experiences.

And the Best Swimming Pool Heater is?

Our favorite is the Raypak LoNox Digital Heater! This does come with conditions, however. The Hayward Universal-H comes in a close second as it is usually cheaper and comes stock with the cupron-nickel plated heat exchanger which makes it well built for a salt pool or a heavily used hot spa. If you have a salt pool or a hot spa, you should buy the Raypak LoNox Pool Heater and upgrade it to a cupron-nickel plated heat exchanger and pay the extra money or save that money and buy the Hayward LoNox Universal-H Pool Heater knowing you may need that saved money for a repair sooner.

The last point I want to make is for you to understand that these modern LoNox pool heaters have a lot of mechanisms, parts, and computer boards in an outdoor setting . You should expect more expensive, necessary repairs than older heaters had. Aggressive pool or spa water can damage your new pool heater, so make sure you hire a water chemistry certified pool cleaning service in Irvine to avoid prematurely destroying your new pool heater.

swimming pool heaterBe sure and read some of our other articles like perfect water chemistry , so you can follow some basic water chemistry instructions to make your pool heater last the test of time. An efficient swimming pool heater is just another piece of your Pool Heaven in Irvine.

If you need help with any pool or spa projects in Orange County, Ca., provide us your information and we will respond with more info. and a free estimate or if we don’t provide the service, we will have the pool professional we use and trust contact you .

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