Pentair Mastertemp 250 Issues

JeepOverland · May 8, 2015

I have a Pentair Mastertemp 250 heater that's having some problems:

-temperature control only allows increasing the temp, can't decrease it
-cannot turn off manually with "Heater Off" button (you can hear a click, the lights turn off, then it immediately turns back on)
-can't switch from Spa On to Pool On (immediately switches back to Spa On right after pressing Pool On)

I ordered a new control panel board and it fixed the temperature control issue, but added the Spa On problem. After looking at the owners manual, I didn't find much in the troubleshooting section that related to these problems. I've had to turn off the gas and circuit breaker for it to turn it off.

Any ideas on what I should check next?

Thanks!

Pool Clown · May 8, 2015

Replace the membrane (touchpad).

ps0303 · May 8, 2015

Pool Clown said:
Replace the membrane (touchpad).

+1. Membrane is the issue.

JeepOverland · May 9, 2015

Man, that was simple haha I got the new membrane ordered yesterday. Hopefully that'll solve it

Thanks guys! :thumleft:

JeepOverland · May 11, 2015

Thanks again for the help! I installed the new membrane along with that new control board and everything is working like normal!

Pool Clown · May 12, 2015

Just a note. The main reason that those membranes fail is due to the UV rays getting to it. There should be a cover that swings across and covers the touch pad. If it is missing, i would get one. They are a bit pricey for what they are, plastic, but worth it for the protection they provide.

Part# is 42001-0008S... i think.

JTE65 · May 19, 2017

I have a Mastertemp 250 as well that is automatically switching from pool mode to spa mode on its own (even though I cannot do that manually). And I cannot change temperature on spa mode to keep it from heating when it does this. I shut it off on the membrane pad and it actually turned itself on and went to spa mode. It is just over 2 years old so appears to be out of warranty. I have repaired and installed pools heaters on prior pools we have owned so am not uncomfortable working on it myself. However, I wanted to first see if this sounds like just a membrane pad issue before I order one.