Sta-Rite Max-E-Therm SR400LP Heater Displays wrong Temperature

[jimmyjames]

I went to use my heater last week for the first time this season and I noticed that when I turned the heater on the display read the temperature as 46 degrees. The heater was set to raise the temp to 80 degrees so the heater came on as expected. I ran the heater for 6-8 hours and monitored the water temperature using a floating thermometer. After that time the display read seventy something but the water was closer to 85 degrees. I turned off the heater since it was hotter than I wanted and forgot about it until the next day.

After doing some research online, I figured the Thermistor must be the problem since it monitors the inlet temperature and I promptly ordered the part thinking it wasn't a big deal to fix. Today the part came and I installed it and thought that wasn't too bad. Then I turned the heater on and again, the display read 46-48 degrees. I let the heater run for a few minutes and no change in the display so I turned it off.

Everything I have read seems to indicate that when the Thermistor goes bad, the reading is 126 and the heater won't fire up. My problem is the opposite. My only thought is that the wiring could be bad from mice since I have had that problem in the past. I changed the control board and keypad a couple of years ago so I am hoping that isn't the problem.

Has anyone heard of this type of problem before?

Thanks for any assistance you can offer.

 

[ps0303]

Separate the to halves of the top of the heater and then remove the two clips on either side of the dome and visually inspect the board underneath the dome. Like you said you might have some mice damage or the board is bad. Obviously also inspect the wiring as well.