Hayward H400 heater -no internal bypass valve found inside?

[ememen]

Had our pool/spa built in 2003 with a Hayward H400IDL heater that recently started knocking with a broken internal bypass valve baffle. Upon removing the header (and broken baffle pieces) I discovered that there were no valve parts installed inside. No valve, no guide shaft, and no spring. The only other loose part inside was the flow control thermostat.

Any guesses as to why these parts are missing? Could it be a manufacturing mistake? Corrosion and disintegration? The heater has always worked flawlessly and there are no unusual sounds or flow problems when pool and pump are operating. The heater has never been serviced since installation.

I bought a rebuild kit and am planning to install all the parts as per the diagram.

 

[Texas Splash]

Good morning and welcome to TFP! I'm not a heater owner, but I hate to see new member questions sitting without a reply. So at the very least we're happy you made it to TFP. As for your heater issue, did you ever manage to get it resolved? If not, please let us know and we'll keep post this thread to get others who might be able to help. Have a good day.

 

[ememen]

Thanks! Examination of the heat exchanger showed that it was severely corroded. After more research of that condition, it seems tied to the fact that I didn't have a check valve between the outflow of the heater and the in-line chlorinator immediately following it. So, my best guess is that the elevated chlorine ate the internal parts of the bypass. I think the original design of the bypass used copper hardware. Though still present, the thermostat was also slightly corroded. The pool was installed with a salt water chlorine generator operating for around 5 years before failing. Then I used liquid chlorine before adding the chlorinator around 9 years ago. Although used infrequently, the heater did last 20 years. It was leaking from within, undetected. Lesson learned: protect your heater with a check valve!

 

[Texas Splash]

Lesson learned: protect your heater with a check valve!

Absolutely!