My 10yr old Pentair Mastertemp worked fine until now. It shuts off at 90 degrees, resets and refires after two minutes, then runs a minutes, then shuts off and repeats, so it takes15 minutes to go from 90 to 102. I replaced filter, thermistor, thermal regulator. Flue stack sensor reads 250, No error codes. Appreciate any advise, as this heater was the best I ever owned.
Pentair heater goes on and off after 90 degrees
- Thread starter nadlerus
- Start date
Do you have automation? Be sure the heater is set to 104 and the automation to the desired setpoint. Be sure the water-temp sensor in the automation is good if you have it. Not uncommon for the heater to be set at one temp and the automation at another. Even after years of use, sometimes "someone" makes a change.
Last edited:
- Jul 21, 2013
- 53,111
- Pool Size
- 35000
- Surface
- Plaster
- Chlorine
- Salt Water Generator
- SWG Type
- Pentair Intellichlor IC-60
Check the bypass valve - Pentair MasterTemp Heaters - Further Reading
If the bypass valve is broken the heater will short cycle and make noise. If you look in the hole where the thermal regulator goes, you should be able to see the black disk. If you look in the water inlet, you should be able to see the spring.
You will have to take the manifold off to replace the Internal by-pass kit P/N 77707-0001.
Guide to replacing the bypass valve is for the residential MasterTemp model.
The ASME commercial MasterTemp model has a different manifold with a 2-inch Pipe Plug, (for access to Internal Bypass Valve), located at the top of the Manifold.
If the bypass valve is broken the heater will short cycle and make noise. If you look in the hole where the thermal regulator goes, you should be able to see the black disk. If you look in the water inlet, you should be able to see the spring.
You will have to take the manifold off to replace the Internal by-pass kit P/N 77707-0001.
Guide to replacing the bypass valve is for the residential MasterTemp model.
The ASME commercial MasterTemp model has a different manifold with a 2-inch Pipe Plug, (for access to Internal Bypass Valve), located at the top of the Manifold.
Thanks. No automation on this older heater. Is set for 104 and temp roughly equal to tub thermometer.