<img height="1" width="1" style="display:none" src="https://www.facebook.com/tr?id=2312617572090101&amp;ev=PageView&amp;noscript=1">

Why Do Pool Heaters Fail So Quickly?

Why Do Pool Heaters Fail So Quickly?

I think we can all agree that the first time you stick your foot in the water of a pool can often be a little bit of a shock to the body. It tends to feel cold and in order to feel comfortable in the water, you have to wait a few minutes for your body to get accustomed to the temperature. Then the water feels warmer than it did when you first got into the pool.

Well, this may be because that pool did not have a heater.

Heaters are a great thing, especially for those cooler days and nights when you want to just hang out in the pool. And a good thing to note is that they are becoming more of a standard in pool packages, but they are not a necessity for pool owners.

Now, you may think otherwise depending on the conditions you live in, but keep in mind that the inclusion of a heater does increase the cost of a pool. And you’ll also want to keep in mind that heaters may need to be repaired in the future, but the MAIN repair we see may not be exactly what you expect.

You see, it’s become more common that we hear from clients that their heater failed in a fairly short amount of time to what they expected to be their lifespan. But it’s not because it’s a bad heater. In fact, heaters fail quickly because of the lack of maintenance, care, and attention to water chemistry.

There is a very specific process that a heater goes through to heat the water that is received from the pool and transported back in a cycle—a process that you need to be familiar with to make sure that you are treating it with proper care. And that’s precisely what we’re going to get into in this article.

We’ll take you through the process of heating water and what problems tend to arise within the heater as well as how to solve these problems.

So, let’s get to it!

Components of a Pool Heater

Its important to understand these basic components of the heater so we can clearly relay the message of why heaters can fail so quickly!

1. Digital Touch Screen

The digital touch screen of the heater allows

you to control its settings, much like the modern-day thermostat that you see in homes.

Jandy Pro Series JXi Heater

It allows you to turn the heater on and off and change the temperature of the heater.

It’s also important to note that when you set the heater at a certain temperature, it will turn on if the water falls below that temperature to bring it back up. And conversely, the heater will turn off if the water temperature rises above the specified temperature.

2. Bypass

Perhaps there are times when you don’t want to use your pool heater. Maybe it’s a pretty warm summer day and you want to cool off instead of getting into some warm water. Well, that’s where a bypass comes into play.

A bypass essentially cuts off the flow of water through the pool heater. So, when the bypass is enabled, water will flow through the filter system without entering the heater and then return to the pool.

Now, we only recommend built-in bypasses like the one that can be an option in the Jandy JXi Pool & Spa Heater instead of external bypasses. Built-in bypasses are more effective and since they are part of the heater, the risk of damage is significantly lower than an external bypass.

3. Heat Exchanger

Here is the main part of the heater and what actually heats the water as it flows through the filter system.

The heat exchanger can be compared to the radiator in a car as they both have a similar flow of a liquid in the same manner.

Amazon.com : Hayward HAXHXA1253 H250 Heat Exchanger Assembly ...

The heat exchanger is made of either copper or cupero nickel. Water will flow through a set of tubes and during this process the heated copper or cupero nickel will heat the tubes, thus heating the water. And then, the heated water will return to the pool.

We should note that water will flow through the heat exchanger both when it is on or off. When it is off the copper/cupro nickel will not be heated, so the water won’t be heated either. It will remain at the idle temperature. But keep in mind that the only time water will not flow through the heat exchanger is if you have a bypass and the bypass has to be enabled.

So What Causes a Pool Heater to Fail?

Now that you know the components of a pool heater and the process of heating water, you’re probably wondering what causes them to fail. Well, it really comes down to one thing—water chemistry.

It is essential that you keep a close eye on water chemistry at ALL TIMES! This is not just important for the heater but for the entire pool!


Below are the proper ranges for the three most basic things to watch when it comes to water chemistry.

Free Chlorine – 1.0 – 3.0 

pH – 7.0 – 7.4

Alkalinity – 80ppm – 150ppm

You need to regularly check making sure you have chlorine to keep water clear and more important sanitary. You need to make sure that the pH and alkalinity level of the pool water is at the level it needs to be to be sure the water is not too acidic or basic. Failure to do so can be detrimental to not only the pool but (HINT,HINT) the POOL HEATER, specifically the heat exchanger.

You see, when the pH level and alkalinity level of the water drops (this can happen many ways but the most common we see is when clients over dose the pool with basic chlorine tabs (Tri-Chlor) the water will become acidic. And when the acidic water makes its way to the heat exchanger, it simply starts to erode the heat exchanger. 

You may wonder why a heat exchanger can be affected by water since its purpose is to funnel water through the filter system. Well, copper and cupero nickel are great conductors and carry heat at very efficiently allowing it to be transfered into the pool water. The negative is that very acidic water can damage NOT JUST THE EXCHANGER BUT REALLY ANY MATERIAL. Really think about it with the exception of plastics and polymers, acid will destroy basically anything. So the chances that you are that if your heat exchanger got destroyed by the pH and Alkalinity being too low then the rest of your pool is taking a beating as well. It just so happens to be that the heater has a soft metal in it that usually goes first!

Back to bypassing your heater. As we stated earlier, we only recommend built in bypasses like the one mentioned earlier from Jandy. Lots of people think that they can just not truly take care of the pool water and choose to just bypass the heater with a plumbing loop. It’s a nice thought but in reality you are just dodging the issue of correcting the water chemistry and damaging the rest of the pool. In addition a plumbed bypass may cause you other issues as well. It is possible with a bypass for the heat exchanger to get clogged with scaling carbonates. When water gets hot inside the copper/cupero nickel tubes, calcium wants to seperates from the water molecules and sticks to the hot tubes of the exchanger. When this happens, calcium deposits build up inside the tubes over time. As a result, it is harder for water to pass through the heat exchanger freely, leading to clogging and the heater will not fire (for safety reasons) and causes the heater to fail.

How fast can a heater issues like this take place?

We here at Royal Pools have seen heaters become clogged or melted from anywhere between 30 days to with in 6 months. The key thing to remember here is, just because the water is clear doesn’t mean its balanced or safe for swimmers/your pool equipment.

In conclusion

As you can see, water chemistry is a pretty big deal and we didn’t even talk about what it can do to other parts of your pool! Chemistry is not only important for the safety of the pool heater but, the rest of the equipment, the pool surface, and obviously for swimmers as well. It doesn’t take long for improper water chemistry to begin affecting said equipment. Thus, the MAIN reasoning for the quick failure of pool heaters.

So, we hope that you understand that your care for every aspect of your pool from the water to the equipment is all tied together. Improper care for your pool can make the consequences pile up quickly, so it’s important to keep up with regular maintenance. Otherwise, failure to do so can result in more hassles and more money our of your pocket.

If you’d like to learn more about water chemistry and how to care for your pool please visit out Learning Center! We’re always keeping you up-to-date on everything you need to know about inground swimming pools!

Visit our swimming pool learning center