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Rick, General Contractor
Category: Pool and Spa
Satisfied Customers: 21801
Experience:  Licensed construction supervisor with 35+ yrs. experience.
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I have a Pentair Minimax NT Pool/spa heater that is starting

Customer Question

I have a Pentair Minimax NT Pool/spa heater that is starting up fine and running for about 15-20 minutes before the burner shuts down and the service light comes on? Any advice?
JA: Who manufactured the spa?
Customer: In ground pool and spa
JA: Do you plan on doing the work yourself?
Customer: yes if possible
JA: Anything else we should know to help you best?
Customer: I think this is it
Submitted: 4 months ago.
Category: Pool and Spa
Customer: replied 4 months ago.
Any Thoughts on this repair?
Expert:  Rick replied 4 months ago.

Welcome to Just Answer, my name is ***** ***** I will do my best to help you with your

issue. First I’ll need some more info so I have a more complete picture of your situation.

What LED's are lit on the panel when/after it shuts down?

Customer: replied 4 months ago.
when I first turn on the the following all show green/on .....Power, TStat, Aux, Press then I switch to SPA or pool heat and the heater kicks on and starts fine and the Heat LED is green and all the above are green. Then about 15-20 minutes later the flame shuts down and the Heat light (green light) goes off and the Service light is Red. Hope this helps
Expert:  Rick replied 4 months ago.

This is usually a problem with the high limit sensors. There are 3 LED's on the back of the board. Which ones are lit will shed more light on this.

Customer: replied 4 months ago.
I won't be at the property to test until Thursday. I'll check and email you one I'm there. Thank you
Expert:  Rick replied 4 months ago.

You're welcome

Customer: replied 4 months ago.
Hi rick! I'm at the home now testing the heater. The leds/lights on the inside of the circuit board that are lite up when the heater/flames goes out is the top two. See attached photo
Expert:  Rick replied 4 months ago.

Ok, you need to check for 24 VAC at the Fenwall ignition control (top of the control > 24 VAC & IND terminals). If you have no voltage there then you have to trace the leads back to the transformer and check for bad connections and voltage across each side of every device in that circuit. Or you can power it down and check continuity across each device.

Customer: replied 4 months ago.
it's not a problem with the high temp thermostate? I don't have a voltage tester with me today so I'll have to come back tomorrow with one and check the wiring as suggested.
Expert:  Rick replied 4 months ago.

Those indicator lights could indicate a hi limit fault. You need a meter to check. The other option since you don't have one is to jump out (one at a time) every device in the circuit between the transformer and the Fenwall

Customer: replied 4 months ago.
Rick, I'm still trying to figure out the problem. Not real familiar with using a multimeter so I'm unsure how to test. I did order a new Thermistor probe and installed today but it didn't fix the problem.
Expert:  Rick replied 4 months ago.

You set the meter on an AC voltage scale above 24 vollts (200 is common) then probe (1 probe on each terminal)the Fenwall terminals mentioned above. Also you don't need a meter to jump out the device between the Fenwall and the transformer. You just connect the 2 leads together.

Customer: replied 4 months ago.
Hi Rick, thanks for your patience. I'll be heading back to the property on monday/ Tues next week so I'm gonna check it out. I also learned how to check the ohms so I'll try that on the high limit switches. I'll email you when I'm there. Thx