My master temp 400hd says that the water temp is 98 when it is really 73. The heater comes on and heats the water to 104 but it is really only 79. What is broke?
The temperature is not reading the actual temperature of the water. The system thinks it is heated to the set temp and shuts down.
Pool & Spa - Pentair
Answers & Comments
Replace the temperature probe on the heater