Premature heater failure due to corrosion

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G

Greasemonkey

Member
Sep 10, 2022
10
Canada
Pool Size
10000
Chlorine
Salt Water Generator
SWG Type
Hayward Aqua Rite (T-9)
Hi all, brand new so please let me know if I’m off base anywhere.

I’m a relatively new pool owner in Canada with a Pentair MasterTemp250HD that has failed at month 20 due to corrosion.

The pool installer maintained the pool for the first season, I’ve been doing it this season. I’m somewhat obsessive about the chemistry - checking it 2-3 times per week. It’s a salt water pool with a Hayward SWG. It’s a small pool - 10,000 gallons.

Typically I find the PH high, and add approx 1L of muric acid per week (maybe 2 weeks).

There is no check valve between the heater and SWG.

Last week the heater started leaking, we called the pool company - they sent a tech out right away to inspect and sure enough, it’s corroded completely. Destroyed. They say it must be me - not managing the chemistry well enough (I feel as though they’re trying to selling me into a weekly service contract).

Alk and stabilizer are typically perfect (in fact I’m not sure I’ve had to adjust since the spring opening).

What could I have done so wrong in 4/5????

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Have you kept track of your test results? If you use the poolmath app it makes it pretty easy to shown them what the chemistry has been. Maybe doesn’t help now.
 
Bperry said:
Have you kept track of your test results? If you use the poolmath app it makes it pretty easy to shown them what the chemistry has been. Maybe doesn’t help now.
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Unfortunately not - I’ve started a super simple spreadsheet to track and I’ll checkout the pool math app.
 
Greasemonkey said:
The pool installer maintained the pool for the first season
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They probably used tabs in the feeder.

I an 99.9% certain that the damage is due to tabs in the feeder while the pump was off and the chlorine migrated into the heater and destroyed the heater.

The pump should never be off when there are tabs in the feeder and there should be a check valve between the heater and the tab feeder tubing connection.
 
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I agree with @JamesW , that is corrosion damage from chlorine pucks sitting in a feeder. Even if was only used during startup, that’s enough time for the damage to be set in place. Then, when you switch to using your SWG, it was just a slow roll to failure. You don’t need a check valve when you are only using an SWG. But, if you have a tab feeder, you absolutely need a check valve to keep that corrosive mixture from back flowing towards the heater when the pump is off.

My guess is the damage was done by your pool service company. They almost always use tabs and ignore SWGs because they don’t like dealing with them. Then, when you took over, the damage was already done.

You will be blamed and they will not take responsibility. It will be highly unlikely that you will be able to prove that it is their fault and so you’re left with the bill. Sucks, but that’s the reality.

Your option is to have the heater replaced or have someone try to replace the heat exchanger. I’d simply go all new and keep the old heater for spare parts (except for the wrecked heat exchanger).
 
JamesW said:
They probably used tabs in the feeder.

I an 99.9% certain that the damage is due to tabs in the feeder while the pump was off and the chlorine migrated into the heater and destroyed the heater.

The pump should never be off when there are tabs in the feeder and there should be a check valve between the heater and the tab feeder tubing connection.
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Hmmm, there haven’t been pucks/tabs in there that I’ve known. Certainly not with the pump off. When’s the marblite was curing they were adamant about it and came to check several times a week.

That said, I see the feeder is on now. Should it be turned off? Or even uninstalled? And is a check valve still suggested (knowing it’s not being used)?

Also, because the pool is over salted (4,000+) could that have caused the same issue if the pump was off?
 
No, high salt does not cause corrosion damage.

It is the acid in Trichlor tablets that causes the corrosion.
 
ajw22 said:
Your pool installer did not follow Pentair installation instructions in the Mastertemp manual requiring a check valve on the heater output if a chlorinator is installed.
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That makes it a defective installation and the builder is liable due to workmanship defects.

It is considered to be an error and/or omission for a professional service such as design, engineering, architecture or installation.
 
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In my opinion, the damage is from tabs in the feeder.

I would get rid of the feeder.

I would ask the builder to replace the heater under their construction warranty at their cost.

The installation is defective and their service was also probably defective due to having the pump off while there were tabs in the feeder.

Is the pump on a timer?
 

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