Mastertemp 400 HLS Cycling

[mcinlb]

Mastertemp 400 heats fine until temperature gets to about 86-88 degrees and then starts cycling with the HLS led lit.

- Replaced HLS and Thermal Regulator (aftermarket- opens at about 130 degrees) in February 2023. >> Problem went away for a month or so and is now back.

- Ran heater w/o thermal regulator to test and >> No HLS cycling.

- Checked manifold bypass valve / spring >> They're both intact.

Anything else I can check? Is it possible for a Thermal Regulator to go bad in just a few months?

Thanks for the help!

 

[ajw22]

Yes, we are seeing quality control issues with the replacement thermal regulators.

Try a genuine Pentair replacement.

 

[JamesW]

Check the stack flue temperature.

 

[mcinlb]

Thanks everyone. So I went through 3 different aftermarket thermal regulators (ARU on Amazon) and only one of them was even close to opening at the correct temperature (120 deg).

After less than a month, it stopped working altogether.

Was finally able to get a Pentair thermal regulator and it opens properly at 120 degrees. Installed it and will test and see if the cycling has stopped this weekend.

So word to the wise.. don't waste time / energy with aftermarket thermal regulators.

@JamesW I think it would be a good idea to add a note re: aftermarket thermal regulators in this wiki.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[JamesW]

Check the stack flue temperature.

 

[ajw22]

@JamesW I think it would be a good idea to add a note re: aftermarket thermal regulators in this wiki.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Not James but done.

 

[JamesW]

Pentair does not make thermal regulators, so it is hard to say who makes what.

Even the Pentair regulators seem to have issues.

Other parts also seem to have quality control problems.

SFS, HLS, AGS etc. are all less reliable lately.

Pool - Vernet Group

www.vernet-group.com

 

[mcinlb]

If it helps, all of the Pentair thermal regulators that seem to have worked properly and are marked Caltherm. Also, @JamesW Thank you for updating Wiki!

 

[JamesW]

Also, @JamesW Thank you for updating Wiki!

I don't remember doing that, but you're welcome.

Most likely, it was Allen.