Master temp 400 calibration

[Rick T]

Hello all. I’ve had several issues with my Mastertemp 400. I finally have it working after several parts replaced and a gas pressure regulator installed. Now when I set the spa to 97 it goes to 101. If I set it to 90 it goes to 94. The display will say what I have set but when it got to 101 we both felt like it was too hot. I used my meat thermometer, thermopen, to check and I trust it’s accuracy. So how do I calibrate the heater down 4 degrees? Thx.

 

[JamesW]

Replace the thermistor or use a 10K ohm resistor to test the board temp reading.

Test only and not to operate.

The reading should be 76 or 77 degrees at 10 k ohm.

 

[Rick T]

I bought an all new manifold replacement kit.

• Complete Set of Components: Includes all essential parts such as manifold bypass valve kit (77707-0001), water pressure switch (42001-0060S), automatic gas shutoff switch (42002-0025S), high limit switch (42001-0063S), thermistor (42001-0053S), ensuring the integrity and functionality of the replacement assembly.

I thought possibly the thermistor was bad so got yet another new one. No change. I tested the thermal regulator in the kitchen sink. It worked as it should. I’ve also replaced the mother board and touch pad (non oe part from Amazon).

 

[JamesW]

Complete Set of Components

Pentair or Cheap Chinese Generics from Amazon?

Link?

 

[Rick T]

I’m sure they were the cheap knock offs. The 2nd thermistor that is in there now is pentair. The motherboard and touchpad are knockoffs.