Question about Pentair Minimax NT Heater

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I have a Pentair Minimax NT. About 7 years old. I can get the heater to light but it will only run about 10 minutes and then shuts down with error code E04. The fan is still running at full force. If I shut everything off all the way to the breaker and let sit for 15 minutes I can get it to fire back up but will only run for about 5 minutes. I have checked the tubing from the fan to the pressure switch and it is fine. Can you tell what to check next?

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Good day!

Actually E05 and E04 can be caused by the same problem. Gas pressure problems likely cause the heater not to rectify (e05), and sometimes explosive combustion upon ignition (e04).
The air flow could be enough to close the switch but upon ignition it bounces the air flow switch out, and shuts the heater down w/ an e04 message.

If the heater starts up and immediately goes into e04 then it is an airflow issue or detection of airflow issue.
These problems can be very tricky to diagnose without the proper instrumentation.
I would say it would be one of the 3 problem. And I would check them in this order.
1. Ignitor (about the only problem most homeowners can solve themselves).
2. Gas Pressure.
3. Combustion air flow. (indoor only)
A modification to the airflow path could be required. This should be done by a trained technician. I have had to do this on several heaters in order to get them to work reliably. They can work with the pentair factory or local reps to execute this.

Thank you and good luck

Posted on May 24, 2011

  • bonifacio gomez
    bonifacio gomez May 25, 2011

    Please don't forget to rate my answer


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The Pentair MiniMax 100 pool heater is designed for above-ground pools and spas. The MiniMax has the ability to raise the temperature of a pool well above 80 degrees, and a spa up to 104 degrees. This unit will last up to 10 years and require little maintenance. However, as with most heating systems, there will come a time when wear and tear will affect performance. Before this happens, a little preventive troubleshooting will go a long way to extending your MiniMax heater's life. Problems to check include thermostat issues, venting, pressure switch and flame adjustment. Pools

Posted on Dec 19, 2013


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SOURCE: E04 comes on after fan purge cycle-Pentair minimax nt pool heater

This is a fan falure code. It can mean the fan has problems (not likley if the fan goes and isn't labored) You have a sensor in your exaust (probally not this if you don't get a good start) The culperet is probally in the negetive pressure sensor. This is a 2-3 inch disc with wires going to the controls and a rubber tube going to the fan. Pull the tube from the fan and make sure the fan fitting is clear (poke with a tooth pic) Be sure their are no kinks in the hose. If the heater is 4 years old the diaprahm could be bad in the pressure sensor. Check the other things first but this is probally your problem. Good luck, hope this helped.

Posted on Jan 26, 2010

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