The Pentair Mastertemp 400 is one of the most popular swimming pool heaters out there that are known for efficiency and reliability.
If you take good care of the Mastertemp, it’ll last for a very long time. However, even with the utmost care, the heater is bound to encounter some issues that you’ll need to fix, and that’s where this guide comes in handy!
In today’s article, we’ll walk you through some of the Pentair Mastertemp 400 common problems and recommendations on how to troubleshoot them. So without further ado, let’s dive right in!
1. The Heater Shuts Down After a Few Minutes of Turning On
Ignition problems are pretty common among all gas-powered machines. However, when that happens with the Pentair Mastertemp 400, it’s mostly caused due to poor water circulation.
In some cases, the heater will start fine but will shut itself off in a few minutes. In that case, the Pentair Mastertemp 400 is also having problems with flow, whether it’s water or gas.
As a safety precaution, the Mastertemp is designed with an anti-overheating system that shuts off the machine when it overheats.
To troubleshoot your swimming pool heater, you’ll need to start it again and check the temperature display. If the screen is giving an accurate temperature reading, you’ll need to check the gas supply system and the pilot tube.
In most cases, either of them is going to be clogged due to residue in the water. This happens when you use water with high mineral content. To avoid this problem, clean the pipes and use soft water instead.
2. Inaccurate Temperature Control or Display
Among the most common problems associated with all pool heaters and not the Mastertemp 400 alone is inaccurate temperature control. In some cases, the water can become too hot or too cold. Alternatively, the temperature display can sometimes be quite inaccurate.
Of course, almost any temperature-related problem in the Pentair Mastertemp 400 will be traced back to some sort of damage to the control board, the thermostat, or the thermistor.
To fix that, you should consider removing the panel to expose the internal parts of the heater. After that, look for the thermostat and try to replace it with a new one by pulling the malfunctioning one-off and installing the new one.
3. Reduced Water Flow
Pool heaters rely heavily on the efficiency of the pool water flow in order to operate. If the water flow is slow, the heater won’t be able to work properly.
If you notice erratic behavior coming from the Mastertemp, such as shutting down, or not heating properly when it’s on, you should check the level of the water in the pool, as these heaters are designed to operate at certain flow rates.
If the water level is moderate but the flow is still poor, you might want to check the strainer basket near the pump. In most cases, it’ll be clogged with debris or leaking due to cracks in the lid of the basket.
If the strainer basket is clean but the flow is still poor, you might want to test the voltage reading of the sensors and the pressure switches of the heater.
4. Limescale is Showing in the Water
Another problem that is associated with using water that contains a high concentration of minerals, especially calcium, is showing limescale on the surface of the water.
This is known as “scaling”, and it’s pretty common in nearly all types of pool water heaters out there. Scaling affects several parts of the heater. It can damage the valves of the water heater, and reduce the efficiency of the radiator.
If you ignore scaling long enough, corrosion will start to kick in and the Pentair heater will eventually stop working altogether.
Unfortunately, if scaling is apparent on the surface of the water, it’s already too late for the heat exchanger, and you’ll need to replace it with a new one. Also, try to use soft water to reduce the impact of minerals on the heat exchanger.
5. The Heater Is Leaking
When the Pentair Mastertemp 400 is leaking water, it’s usually due to a faulty part in the heat exchanger. In most cases, the thermal governor that controls the cooling fans of the heater is the culprit.
Ideally, the Mastertemp 400 will last for up to 15 years with good maintenance. However, the thermal governor may malfunction in as little as 5 to 7 years. In that case, you have to replace it with a new one because thermal governors aren’t fixable.
6. The Heat Exchanger is Showing Heavy Corrosion
The heat exchanger is, by far, the most important part of the heating mechanism of the Pentair Mastertemp. Since the heat exchanger is always in contact with pool water, it’s always at risk of heavy corrosion.
When that happens, the Mastertemp will make audible boiling noises sometimes. This problem is also common in pools that have a pH level that is too high or too low.
In some cases, the heat exchanger can be saved or even fixed. To determine that, you’ll need to have a professional check the heat exchanger and let you know what should be done.
The interior of the tubes in the Mastertemp is made of corrosion-resistant copper. However, leaks can easily cause corrosion of the interior parts of the heater.
To prevent that in the future, make sure that you always check the pH of the water and clean the filters regularly. If you’re getting a new one, consider getting a cupro-nickel heat exchanger because it’s excellent at resisting corrosion.
The Bottom Line
With that said, our guide about the Pentair Mastertemp 400 common problems and possible solutions comes to an end.
The Mastertemp 400 is pretty durable and should last anywhere between 7 to 15 years depending on your frequency of use and maintenance.
To extend the life of your swimming pool heater, make sure that you address any problem that it shows no matter how minor it is. This will also help you save money by avoiding costly repairs and replacements.