Hi,

My pool heater has a problem. It heats the spa water fine to about 95 degrees, then the heater stops heating and cycles on then off for a few minutes at a time until it reaches 102 (set limit). This takes much longer than usual to heat up the spa with this happening. The water also does not feel like it is 102 when it says it is?? The SERVICE HEATER light and the HLS led (under the control panel) turn ON when the heater shuts off, then resets themselves after a few minutes then the heater turns on again.

I am thinking the high temp level sensor may be bad. I removed it(chased the wiring of the HLS led to that sensor), inspected visually, and put it back in. The markings on it are SA TOD 441631 316109 L135F. Is this a common part that fails.

Please help.

Michel

yes it could be the problem. Check your manual, I believe there might even be a slight adjustment for the high limit sensor.

Definitely a possible problem. Replace the sensor and see if the problem continues. It is also possible that something is clogging the heat exchanger and making it overheat. Improper flow could be causing the water to get too hot in the heater, which would trigger the high limit sensor. A clog could be anything from hair, sand, to calcium buildup. This can be a major problem, but hopefully it's just a bad sensor.

Did you ever get this sorted? I'm having the exact same problem with my Pentair Master Temp. Of course it started 1 month after I fired my pool maintenance company, and 2 months after my 1 year PB warranty ran out...

Drogers-

If you've got an HLS light on you've either got overheated water going into the heater, a flow obstruction beyond the heater allowing the water inside to get too hot, or a bid high limit sensor.

Assuming the water is cold, if you turn the unit off for about 10 seconds and then back on again and the HLS light immediately comes back on (as in before the heater ever fires up), then it's a bad sensor (or possibly a bad board but you'll have to replace the sensor first to find out).

Tim

Bringing this back to the top, as I have the same problem and curious if any solution was found. I called Pentair and they said it sounded like a restricted heat exchanger... Is this something a DIYer can fix/clean? I already changed out the HLS.

Chris

You need to remove and inspect the thermostatic by-pass. It resembles an automotive thermostat. If the bulb has corrosion, or perhaps a small crack, may look like a green crack, then it needs to be replaced. It is the plug with castellations between the inlet and outlet ports (water).

Note: if your HLS is opening, then closes, its working properly. The HLS is rarely the problem but more a symptom of another problem.

Thanks, I will check it and report back.

Chris

Pentair equipment has a three year warranty if you purchased three pieces at the same time. Call Pentair

OK, got some time to check this. I also should let you know it is an ASME heater. I pulled the top brass plug and gained access to the bypass valve. Some corrosion, not not to bad. Looks like this is suppose to leak a little anyways. Looks like I have to pull the lower pipe off to access the thermal regulator. If this is stuck closed or low flow, I think it would cause the problem I am having. Not entirely sure how the heater works. But seems like the thermal regulator valve opens up when it gets hot, if it is closed the bypass valve opens up and water circulates that way? Thanks again for the help....

Chris

Brass plug is not for access or inspection. This is what you should remove to get to the therm. b-pass.

The ASME model has a completely different header.

You do have to remove the inlet pipe to access the thermal regulator. It's a PITA if the installer didn't make provision for doing so.

Yes, it will be a PITA. Have to cut and redo everything.....Hope to have time this weekend. I already got a new thermal regulator ready to go in, hopefully it will fix it.

Chris

It is fixed, replaced the Thermal Regulator and works like a champ. The old regulator was corroded with some blue stuff. Can the salt do this or did my chems get out of whack?

It was quite a project but I added unions this time for easy access if needed in the future. Appreciate the help...

Chris