Seeking Advice on Pentair Pool Heater Issues

[AndrewR69]

Hi everyone,

I'm reaching out for some advice regarding my Pentair MasterTemp 400 . Over the past six months, I've been experiencing a "backfire" sound whenever the heater starts up. After doing some research, I suspected that the issue might be due to low pressure on the gas intake. However, I didn't take any action until the weather got colder and I started using the heater more frequently.

For context, my pool was installed in October 2021. In December of last year, I finally called the pool company to inspect the heater because the backfiring sound had become more frequent. When they came out in January, they informed me that the bowl inside the heater was rusted and that it would likely require an entirely new unit.

To make matters worse, I found out today that the warranty on the heater expired in late November 2024, just a couple of weeks before I initially called the pool company. Now, I'm faced with the prospect of spending over $4,000 on a new unit for a heater that is barely three years old.

I'm wondering if I have any recourse in this situation. Has anyone else experienced similar issues with their Pentair Pool Heater? Is there anything I can do to avoid having to replace the entire unit? Additionally, if I do end up needing a new heater, what steps can I take to prevent this problem from happening again?

Any advice or insights would be greatly appreciated!

Thanks in advance,

Andrew in Houston, TX

 

[an1vrsy]

Andrew, Let me bump this post to get some experienced eyes on it. Just hang tight.

 

[ajw22]

Do you use Trichlor tablets in the tablet chlorinator?

I do not see the required check valve between the chlorinator and the heater as required in the Pentair Installation Manual. Even with the check valve acid from the tablets can backflow into the heater and destroy it.

Without the required check valve I doubt you have recourse with Pentair.

Other reasons heater get damaged are improper water chemistry. Either low pH or low calcium. Or running the heater in the winter with low water temperatures causing Heater Condensation - Further Reading

 

[wireform]

I'm not understanding how the rust gets there. With all the gaskets in place that should be dry.

 

[AndrewR69]

Do you use Trichlor tablets in the tablet chlorinator?

I do not see the required check valve between the chlorinator and the heater as required in the Pentair Installation Manual. Even with the check valve acid from the tablets can backflow into the heater and destroy it.

Without the required check valve I doubt you have recourse with Pentair.

Other reasons heater get damaged are improper water chemistry. Either low pH or low calcium. Or running the heater in the winter with low water temperatures causing Heater Condensation - Further Reading

I have been using Trichlor tablets in the chlorinator at a very minimal setting. This has just been as a backstop incase I miss a day or am out of town. I primarily use liquid chlorine. The check valve is right before the Chlorinator.

 

[ajw22]

I have been using Trichlor tablets in the chlorinator at a very minimal setting. This has just been as a backstop incase I miss a day or am out of town. I primarily use liquid chlorine. The check valve is right before the Chlorinator.

I see the check valve now but the acid will damage the check valve and then leak into the heater.

You can try to make a warranty claim with Pentair and see how they respond.

 

[jonny2342]

1. Check for any cracks or damage around the plastic connections for the gas tubing.

2. Check that the igniter isnt loose or leaking around it. Honestly, they are pretty cheap to replace so you can always try replacing that part.

3. Not sure why you have so much rust on the lid. I dont get type if rust in the Austin area. Maybe it is more common in Houston though.

There isnt going to be an easy way to inspect inside of the tub without taking it apart. Before I would spend 4k a new heater I would probably have someone open the tub an inspect it. There is a reasonable chance that if there are damaged/rusted parts in the inside that you can replace them for much cheaper than a new heater. Sometimes companies are quick to replace them when they just need some TLC.

If you do get a new heater i would definitely try to salvage any parts off the old one as spares and keep them. Especially if the heat exchanger is still good etc.

also, this thread might he helpful.

Pentair Pool Heater makes a loud bang (backfire?) when it ignites.

Thanks @Pdxonthego1. I’ve had to put this on hold for a bit as my son just got married, but I’ll be tearing into this shortly. Not sure how the 206a compares to the pentair or if there is a similar “sping in the heater core of the bypass line” but it’s with checking out. I’m also wondering if...

www.troublefreepool.com

 

[AndrewR69]

Thank you for the responses.

I had the neighbor's pool company take a look at the heater, and they didn't find anything wrong. However, they didn't perform a deep inspection—just turned it on a couple of times, and it seemed fine. Since then, I've fired it up 5 or 6 times without any issues or "backfiring." I've also ensured that none of the other appliances in the house were using the gas lines, thinking that pressure might be a factor. Most of the time, I run the pool heater during cooler months when the furnaces are on in the house.

I'd like to have someone come out for a more thorough inspection. Is there anything else I should check on my end before calling a professional? I'm comfortable handling the pool chemistry a few times a week, but the heater's internals are beyond my expertise. What's the best way to find a reputable repair technician, or does anyone have any recommendations in my area?

 

[ajw22]

Show us pictures of your house gas meter with all the labels on it.

We gave seen many people have 250 BTU meters with 400 BTU heaters which limit gas flow.

 

[wireform]

Among the qualities he possess he has to be proficient in gas valve adjustments to be sure. You need to have enough gas flow to the heater with everything that's hooked up and if you are short you'd need a bigger gas meter.

 

[AndrewR69]

He are the pictures of the gas meter.

 

[ajw22]

Hard to read that label but it looks like the gas meter is undersized. Contact your gas company to confirm and determine what the process is to upgrade the gas service.

 

[AndrewR69]

From looking up the gas meter, it appears to be rated for 175,000 BTU. I have already scheduled for the meter replacement to happen on Monday the 3rd. Cost is $350. They said they are going from a 4oz regulator to a 2lb regulator.

Give the rust that is on the heater, do I need to be overly concerned about that? Or as long as it doesn't have any other issues it should be okay?

 

[ajw22]

From looking up the gas meter, it appears to be rated for 175,000 BTU. I have already scheduled for the meter replacement to happen on Monday the 3rd. Cost is $350. They said they are going from a 4oz regulator to a 2lb regulator.

Great.

Give the rust that is on the heater, do I need to be overly concerned about that? Or as long as it doesn't have any other issues it should be okay?

It is not clear the rust is an issue if it is on the surface and has not put holes in the burner can.

 

[1poolman1]

From looking up the gas meter, it appears to be rated for 175,000 BTU. I have already scheduled for the meter replacement to happen on Monday the 3rd. Cost is $350. They said they are going from a 4oz regulator to a 2lb regulator.

Give the rust that is on the heater, do I need to be overly concerned about that? Or as long as it doesn't have any other issues it should be okay?

That rust is just below the blower. Pull one of the lowest bolts on the manifold. Does water come out or is the bolt rusted? If so there is a leak in the heat exchanger and it may be backing up into the blower. There should be no water inside the cabinet of one of those heaters. The only other time I have ever seen rust like that was when a lawn sprinkler was spraying the heater, but the rust wasn't localized like yours.