Pentair MiniMax ch 200m, not sure the last time it was used. Just bought house in October. Pilot will light, but heater does not kick on. Thermostat as a little red light on the back that is on. What does this mean?
Heater won't fire.
- Thread starter Poolsteve
- Start date
Do you have and know how to use a volt/ohm meter. There are several safety switches in the circuit that all need to be checked. I believe the pilot on this unit is controlled by the Power pile. You need to verify the voltage from the power pile with the flame on it to see what it is. Ideally it should be 750 Milivolts. This is used to prove the pilot is on and supply voltage to the gas valve. My first suspicion is that there may be some corrosion on a terminal(s) in the safety switch circuit. Another possibility is the pressure switch is not seeing sufficient pressure to close that switch. Do you have a 2 speed pump? If so try running it on the higher setting.
Appears that you are getting power to the heater. Why the main burner is not kicking on could be caused by a number of things. Here are a few possibilities:
As an FYI to anyone else reading this, I would make it a point to run the heater periodically (as long as your pool is "open" and not winterized) even for just a few minutes at a time. This will help keep the main burner clean and burn off any moisture that may be in the unit. It will also exercise the burner valve to reduce the likelihood of it seizing either in the closed or open position. If you winterize your pool, I would at least put a cover or tarp over the heater to keep as much moisture and debris out of it.
- A bad thermocouple
- The pilot may light and stay lit but the pilot flame may not sufficiently warming the thermocouple enough to open the gas valve to the main burner. If the tip of the flame curls away from the thermocouple, this is a distinct possibility.
- The main burner could be plugged with debris
- The gas valve to the main burner may be stuck closed
- There could be a sufficient level / pool of moisture in the burner or elsewhere in the unit
As an FYI to anyone else reading this, I would make it a point to run the heater periodically (as long as your pool is "open" and not winterized) even for just a few minutes at a time. This will help keep the main burner clean and burn off any moisture that may be in the unit. It will also exercise the burner valve to reduce the likelihood of it seizing either in the closed or open position. If you winterize your pool, I would at least put a cover or tarp over the heater to keep as much moisture and debris out of it.
I do have a multimeter and am great at following instruction. Just need to know what to touch where to test each safety. 
Not to sound like Captain Obvious, but have you checked the owner's manual? My Hayward manual has service level diagrams and troubleshooting trees that helped me with my heater a few years ago.
