Question about Pentair MINIMAX NT TSI IGNITER

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MIni-Max 400 heater cycling

When we have our Mini-Max 400 heater set to heat the spa, the heater cycles on and off. I had a pool repair person replace the flow valve, then he used high pressure to clean out the pipes, and a ton of white crud came out. He also replaced the blower because it was leaking and sucking air, which may have caused improper pressure for the heater to work correctly. After $1000, the heater worked like a champ for a few uses and the spa would heat up in 15 minutes, but now it's cycling on and off again and the spa takes 1hr to heat. The manifold, where the flow valve is installed, seems to get very very hot, then the heater cycles off. I'm not sure if the repair person checked the pressure switch, which I heard could be the problem. The repair person said the heater core could be clogged, but he said this would require me to refinance the house to pay for this repair. Any ideas before I trade-in the wife to pay for more repairs?

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  • dwfilice Mar 06, 2009

    Well, the problem may have been solved. The repair guy stopped by and said the filter basked was quite clogged. I just cleaned it a week ago, but if the lack of flow from even a slightly clogged basket caused the heater to malfunction, then I will clean the basket more often. Usually a sign of a clogged basket is the Kreepy Krauly not working, and it's been working just fine.

  • bruba Apr 16, 2009

    I have the same problem. Happened last winter 2007 - 2008 service man replaced the flow valve, burners clean, worked a little bit and back to the same problem. Watched the heater, heats for about 4-5 minutes all lights green, then you hear an electronic relay disconnect then the red service light comes on and the heater shuts down, 2 minutes later the red light goes out the relay connects, burner fires and the whole process repeats. Any suggestions?



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Sounds like you may have a water chemistry problem more than a heater problem. High pH coupled with the heat of the exchanger in the heater will allow the calcium in the water to precipitate and scale the tubes of the exchanger. Make sure your water is balanced, pH 7.4-7.6. Water balance factors include pH, total alkalinity, calcium, TDS, and temperature. Use the langlier saturation index to determine your water balance. If your water is balanced, you may have a bad thermal governor. If you hear the heater water hammer and bang around and then shut off, you definitely have a scale buildup in the heat exchanger tubes. Hope this helps...

Posted on Sep 17, 2009


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