Hayward H400FDN Heater Coil Assembly leaking after 2 months

[The Big Ugly]

Hi. New to the forum and found it while trying to understand my problem. In September 2023 I replaced the heater coil assembly in my Hayward H400FDN since it was leaking in the coils (heater was installed in 2017 and this was the first time replacing the coils). That assembly started leaking by the tubes in August 2024. I tried to claim repair/replacement under warranty and Hayward looked at the pictures they asked for and said my chlorine levels were too high. We live in Houston area, and I had to shock the pool a lot this summer due to 1) a wind storm in May 2) being rainy and hot during early summer, and 3) Hurricane Beryl in July, so their explanation didn't seem out of line. I replaced the coil again, and now it's leaking around the tubes after just 2 months! (Hopefully the video comes up in the post.) I test the water weekly using a Leslie's 9-Way Pool Water Test Kit and nothing is ever way off. I balance the water and add the appropriate amount of Leslie's Pool Perfect every week.
After finding the leak today, I took a sample to Leslie's:
FCL: 0.9
TCL: 1.28
pH: 7.3
Alk: 30
Cal: 299
CYA: 207
Iron: 0
Copper: 0.3
Phos: 172
TDS: 1200
My test kit showed Alk 80 and CYA 100.

Although there is no check valve between the heater and chlorinator, the chlorinator sits several inches below outlet piping of the heater and the piping goes underground right after the chlorinator. This makes me doubt chlorinated water is backing up to the heater.
Any suggestions as to why the coil failed so quickly, and how I can combat Hayward's expected refusal to honor the warranty.

Pool size 10K, main pump Century SP3210Z1BE (a second one for features), booster pump Pentair LA01N, filter Hayward C4030, heater Hayward H400FDN

Thank you in advance,
The Big Ugly

 

[ajw22]

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[JamesW]

The tab feeder is the most likely cause of the heater damage.

If the pump is off and there are tabs in the feeder, the combination of low pH and high chlorine will easily migrate into the heater and destroy it very quickly.

You need a check valve and the pump should Never be off when there are tabs in the feeder.

 

[PoolStored]

Welcome to TFP!!!

Lots going on.

Starting with the heater. A bit of "downhill" in the return lines isn't going to stop very acidic water from getting from the chlorinator to the heater. With the copper level in the pool, the chlorinator is the likely culprit. A puck chlorinator needs a check valve.

Now, testing...One of the foundations of TFP is self testing. The 9-way is ok, but I'd encourage you to get a TFP recommended kit. Link-->Test Kits Compared
The FC testing is probably the most important. For now, you could add a FAS-DPD FC testing (Taylor K-1515 or FAS/DPD Chlorine Test Kit ) to your kit and be ok.

Now, sanitization and CYA. CYA is added to the pool when you use pucks. When CYA gets high enough, you cannot maintain enough FC to sanitize the pool.
The shallow end...Link-->FC/CYA Levels
The deep end...Link-->Pool Water Chemistry
If your CYA is 90+ on your test kit, perform the diluted CYA test starting at #8 here:

CYA - Cyanuric Acid Test

Cyanuric acid (CYA) is the chemical name for the product commonly called “pool water stabilizer” … Read more…

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Retest the CYA. With a high CYA and a high copper level, it might be time for a partial exchange to get CYA and copper out of the pool. Read up on no drain water exchange here:

Draining - Further Reading

www.troublefreepool.com

Pucks can be a viable option for chlorinating, but when CYA gets to about 60 or so, you will need to replace about 50% of your water to lower CYA to 30. We don't recommend this approach to pool care. We recommend liquid chlorine or a salt water chlorine generator (SWG, SWCG). In Texas, a SWG is the perfect solution.

 

[JamesW]

After finding the leak today, I took a sample to Leslie's:
FCL: 0.9
TCL: 1.28
pH: 7.3
Alk: 30
Cal: 299
CYA: 207
Iron: 0
Copper: 0.3
Phos: 172
TDS: 1200
My test kit showed Alk 80 and CYA 100.

Leslies uses Adjusted TA.

88 - 207(0.280) = 30 ppm.

Borates and Adjusted Alkalinity.​

Adjusted TA = TA – (CYA X CYA C.F) – (Borate x Borate CF)

Borate C.F (correction factor) based on pH.

pH.......CF

7.2.....0.051

7.4.......0.0786

7.6......0.1248

7.8......0.1989

Cyanuric Acid correction factor based on pH.

pH........CF

7.0.......0.22

7.1.......0.24

7.2.......0.26

7.3.......0.28

7.4.......0.30

7.5.......0.32

7.6.......0.33

7.7.......0.34

7.8.......0.35

7.9.......0.36

For example, if the pH = 7.6, TA = 90, Borate = 50 and CYA = 70, the adjusted alkalinity is 90 - (70 x 0.33) – (50 x 0.1248) = 60.66.

 

[The Big Ugly]

Thank you to all for the advise. I'm just so surprised the coil failed this quickly, especially since the original one lasted for years.

 

[The Big Ugly]

Welcome to TFP.

Videos cannot be loaded onto the TFP server. Please load videos to YouTube, mark it PUBLIC, and post a link to the video in your thread. YouTube videos have a SHARE button that will give you the link to copy and paste into the forum.

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Here is the video... there's not much space for me to get a good angle.