Question about Pentair Mastertemp Heater
Heater reaches within 1 degree of desired temp then cycles on and off every 20 seconds. I have changed thermistor and thermal regulator. Do I need a new control board?
Try calibration that might take care of problem otherwise sounds like new board
Posted on Jun 10, 2014
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Posted on Jan 02, 2017
hello, It sounds like you may not be getting circulation thru the heater. Make sure the valves are open to allow water to pass thru the heating system. Some systems use a bypass on the heater so there is not a lot of wear on the coil system in the heater. If it is not circulating it will get too hot and the safety shut down will occure. If you are getting water circulating thru the heater, then the thermocouple or auto start igniter system is not working correctly. It is trying to start and can't then recycles. If the burners are igniting on the startup and then shutting back down you may have a bad control unit or thermal sensor unit. Since the unit is gas have a professional service it for you. Good Luck, RAC
Posted on Apr 20, 2009
This reminds me of some of the High temp sensors ive replaced. I would start with checking the pumps flow to the heater. Make sure there are no abstructions and at least 35 GPM (gallons per minute) running to the heater. If your flow is too low, you will trip the high limit sensor after a short while.
This could also mean you need to clean out the heat exchanger. When an exchanger gets dirty, it blocks the flow of water, slowing it down and "super heating" itdue to the water being in contact with the exchanger for too long. This will also trip the high limit and call for service.
If both the above items check out, contact me @ firstname.lastname@example.org and I will guide you further.
Posted on Nov 23, 2010
SOURCE: Pentair Master Temp 400 E05
If you've already changed the thermal regulator then the only other thing it could be is the flue/flame sensor.
It could be just a loose or bad connection so I'd check them first before replacing it.
If you've got a meter then you could disconnect the sensor and check its continuity (should be 3-4M Ohms). If its OK then check the continuity of the wiring between the sensor and board.
Posted on Jun 12, 2011
My pentair matertemp 400,000 BTU natural gas heater cycles on and off before reaching desired temperature. I completely cleaned the DE filter and flow should not be an issue. When running the spa the pressure is 25. When running the cleaning system (polaris pop ups) the pressure is 30. Burner fires for 80 seconds then shuts off, reignites after 53 ceconds.Any tips on what might be the issue with the heater
Posted on Jul 23, 2011
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