My Pentair Minimax NT heater constantly displays "HI" on the LED readout, and never turns on to heat. As I understand the HI readout, it is an overtemp protection. I looked at the product manual and there is a 115 deg and second 150 deg hi limit thermostat. I assume one or both of these are my problem. Is there a way to determine which thermostat I should replace, or should I just replace both? Or could my problem be something else?
Pool & Spa - Pentair - Minimax NT Heater
Answers & Comments
This could be high limits but more than likely this is a water flow problem. Check to be sure your by-pass is closed or nearly closed. If this is good then you need to remove the water manifold from the side of the heater. Inside you will find another by-pass assembly and you will need to replace this.
Before doing this you can take the wires from the limit switches one at a time and use a jumper wire to by-pass them. This won't tell you if they are bad though just if they are kicking off. If the water in the heater is that hot they are just doing their job.
Sort of a catch 22 but the best I can do from here. Hope this helps, good luck.