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Pentair MiniMax Plus 250 Off and On

My heater will turn on as it should and run for about 1 minute and then the heater will turn off. A minute or so later the heater will turn back on the pool eventually gets warm, but I don't believe the heater to be working correctly... When the heater turns off, so does the heater light and then the service light turns on. I noticed that the flow valve assembly will get very hot towards the end where the relief valve is (as I guess it should). The Electronic Thermostat Circuit Board and Module have recently been replaced so I don't believe them to be suspect. I plan on replacing the thermostat and then I was wondering if the Flow Valve Assembly may need to be replaced. Any ideas? Thanks

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To answer your question....... ensure all flow is good, cleaning the filter, and correct speed if you have a variable speed pump (typically 2500rpm)

If the flow is good and this is happening then it could be the thermal regulator which is on the header of the heater where the water goes in and out. They can get a build up of scale and or corrosion which causes an internal flow issue and can overheat the heater.

The heater also has high limit sensors which will shut the heater off when it gets too hot.
You will want to make sure to get this fixed to avoid melting of the plumbing or internal damage of the heater.

Posted on Mar 29, 2017


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Posted on Jan 02, 2017

  • 246 Answers

SOURCE: pool heater cycles off and on

insert on hot water and see if open or close than on cold water and must reverse from hot. if nothing happen replace

Posted on Sep 19, 2009

  • 2 Answers

SOURCE: Pentair minimax pool heater (1 year old)

Board problem? Did you fix the problem?

Posted on Oct 19, 2009

  • 43501 Answers

SOURCE: My pentair minimax plus 250 M pool heater won't

For most pool heaters, if they will not start up in the spring, the problem is corrosion in the wiring somewhere... I would remove and clean all wiring connections and then try. The amount of current is very small and so any bit of corrosion can cause the unit not to work.

It all so could the t-stat again, but you would need to check that with an OHM meter. No continuity when the heater should be on will confirm that the t-stat is bad...


Posted on May 14, 2011

  • 927 Answers

SOURCE: heater fails to ignite after

I have a pool heater, let me try to do this from memory.
For a gas heater to allow an ignition several things must occur and be proven.
There is a water pressure switch or flow switch to ensure water that will take the heat away from the heat exchanger is there in adequate flow. Find this switch and ensure that it is closing.
Next, a forced air fan starts. There is a switch that closed if air flow is adequate for the amount of gas in the flame. Is that switch closing?
The thermostat must be set higher than the incoming water temperature, is that circuit closed?
At this point, the electronic igniter sparks on my heater. Do you have a standing pilot light?
Next, the gas valve opens. Is the gas valve getting voltage?
If so, once the flame ignites, there is a thermocouple that must sense high flame temperature to allow the gas valve to stay open to heat the water.
There may be more and this may not be all for your heater, but if you have a multimeter, these are some things you can test.
Gary - let me know how you do.

Posted on May 30, 2011

  • 13 Answers

SOURCE: I have a Pentair minimax 250k electronic. Opened

Most of the time I have found the problem to be the thermistor. It is located on the water manifold of the heater. Usually the panel lights, flashes then to 888 and back to dashed lines. SW light is green, and service light is red. It costs 25 to 45 dollars, and takes 5 minutes to repair. New thermistor looks identical to old so replacing it is very easy.
thanks please let me know if this was helpful

Posted on Jun 19, 2011

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