Question about Pentair Minimax NT Heater

1 Answer

I have a minimax propane heater. It will not turn on to heat the water. I have to bypass the pressure switch. Then sometimes that works. When I bypass it. It will take awhile to fire up. I have replaced the pressure switch several times. Still does the same thing.

Posted by on


1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points


    An expert that got 10 achievements.


    An expert that got 5 achievements.

    Vice President:

    An expert whose answer got voted for 100 times.

  • Master
  • 990 Answers

The pressure switch is not a problem it's a symptom. That is to say it's a safety switch. If the pressure runs to low it will shut the heater down rather than let it overheat from too little water flow and cause damage. If you have a by-pass valve make sure that is closed. Then make sure the baskets are clear and the big one make sure the filter is clean. This is usually the problem when the the pressure switch kicks. If all that fails take the pump apart and clean the impeller. That dosn't take much to stop the heater ether. Good luck.

Posted on Sep 28, 2010


1 Suggested Answer

  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.

Posted on Jan 02, 2017


Add Your Answer

Uploading: 0%


Complete. Click "Add" to insert your video. Add



Related Questions:

1 Answer

I had the thermostat , disc contraption out and heated thermostat sensor , seems to work good ,but still won't heat the water exiting unit

the most common problem with these heaters not starting is the pressure switch. you can easily bypass to test it but under no circumstances allow the unit to run with it bypassed.

Jun 18, 2014 | Hayward H Series Pool & Spa Heater 400k...

1 Answer

My minimax heater does not operate when turned on. no ignition nothing.

You do know the pool pump must be running and pumping water to make the heater come on? It could be any number of things, but no or low water flow is a common problem. If your filter pressure is at the normal range, it should fire. There is also a thermal fuse right inside the heater that looks like a piece of wire with spade lugs on both ends. This is also a common problem with these heaters. You can temporarily bypass this fuse link and if the heater fires you have found the problem. DO NOT RUN THE HEATER WITH THIS BYPASSED. After this fuse link you also have a pressure switch, two hi-limit switches, and a circuit board that could be the problem. Not an easy fix unless you understand how they work. Be careful, gas and fire can at the least cost you some eyebrows and hair, at the worst, can explode and kill you. If you don't know what your doing you best call a pro.

Aug 28, 2011 | Pentair Minimax Ch 250,000 Btu Natural Gas...

1 Answer

Hello - I have a Pentair MiniMax NT that is aprox. 5 years old. We have never had any problems with it till this past week. We went to turn on the heat for the jacuzzi, and nothing. The unit shows the...

HI is a code for Water temp over 114. If this is what you have the temp sensor has gone bad. Or thermister. It will be a small tube that slides into the water manifold with two wires coming from it. A white nut sets it in place unscrew this pull out follow the wires to unplug then slip the new one in.

It is also possible that you have enough water flow to close the pressure switch circuit, but not enough to keep the water from getting to 114 F by the time it reaches the temp sensor.

Also, the bypass valve might just need an adjustment . If its bypassing too much water, you will get this code as well.

Hope these ideas help

Apr 25, 2011 | Pentair Minimax NT Heater

2 Answers

The fan in the heater turns on but the heater does not turn on.

Probably a bad circuit board. I have the same problem once the water gets above about 82 deg. I tried cleaning the filter and strainer, cleaning out the heat exchanger, replacing the temperature limit switches, bypassing the pressure switch, and cleaning the ashes off the burner, and none of these worked.

Jul 30, 2010 | Pentair Minimax NT Heater

2 Answers

High pressure, and heater noise

I am not sure if you have solved this issue, or not, but if the PSI on the gauge is high then the problem may not be the heater. When you have the system turned on, and the PSI is reading higher than normal, just the flow of water coming out your return lines. If the flow is normal, like when you clean your filter, then see if you have a way to re-route the water so it bypasses the heater. If the PSI on gauge drops, then the issue is in the heater.

If the flow of water is slower than normal, with the PSI reading high, then you have a blockage somewhere in the system. It could be something simple like removing debris from skimmer and pump backets, to time to backwash, or clean, the filter.

If the flow of water is really hard and fast, with the PSI high as well, then you have too much water going through the system and need to slow it down.

Jun 27, 2009 | Pentair MiniMax 100 Aboveground 100,000...

1 Answer

Heater not working

yor heater has 3 high limits and a flame rollout switch(aka thermal fuse). be advised that bypassing safetys is not recommended and is dangerous.these component failures are symptoms. we need to find causes.if limits are failing look at sooted or possibly a nest on your heat exchanger. if its a flame rollout problem look at obstructed burner or oriface.

Jun 22, 2009 | Pentair Minimax Ch 400,000 Btu Propane...

1 Answer

I have a Mini Max 100 pool heater. The pilot

check pressure switch for proper adjustment and make sure filter is clean so system pressure is normal

Jun 07, 2009 | Pentair MiniMax 100 Aboveground 100,000...

1 Answer

Pool heater cycles off and on

Sounds like a limit switch, although it might mot be bad. If the filter is cleaned, and you have a good return from the pool jets, then you may have a problem with the flow valve in the heater. I would try to bypass the limit switches and see if that stops it, but it is dangerous. If you feel capable enough to try, only do so if there is a pressure relief valve on the header (does not come with heater, but if it was installed correctly then the installer would have to have put one on).

Apr 20, 2009 | Pentair Minimax Ch 400,000 Btu Propane...

Not finding what you are looking for?
Pentair Minimax NT Heater Logo

138 people viewed this question

Ask a Question

Usually answered in minutes!

Top Pentair Pool & Spa Experts

Pj Kiley
Pj Kiley

Level 1 Expert

21 Answers

Jay Finke
Jay Finke

Level 3 Expert

1339 Answers

Bill Jordan

Level 2 Expert

372 Answers

Are you a Pentair Pool and Spa Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides