Pentair MiniMax NT will not fire
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Posted

Have green lights on Pressure SW and Thermostat, Heating light is not on, no error codes, fan runs but heater will not fire.

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Richard,
Posted

Richard,
Does the gas valve ever click or can you smell gas? Also can you see the igniter glow? It might be easier to call our team at 1-800-831-7133. We can assist in troubleshooting the next steps. If you are not familiar or not comfortable with checking voltages through this system, I’d recommend contact a local service company so they can help. For a list of stations in your area: http://www.pentairpartners.com/dealerlocator/dealerlocatorlist.aspx

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I have a similar problem with
Posted

I have a similar problem with my Minimax NT. My Minimax NT TSI w/DDTC does not start. The green power button is lit up on the DDTC but the display only shows "OFF". No error code is shown, but the heater never starts. I replaced the thermister probe (part number 471566) and the water temperature sensor (P/N 520272), which was reading 10°F low. Neither of these items fixed the problem.

If I turn off completely, the screen reads 888. When I turn it back on, the Power LED illuminates and the screen reads "OFF". No matter if I use Pool Mode, Spa Mode, or Remote Mode, the heater never starts. Any recommendations about what to troubleshoot next?

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Mark,
Posted

Mark,
“OFF” is an indication that the pressure switch is not being closed. This could be as simple as increasing flow to achieve the minimum required for this heater or it could mean a possible issue such as with the switch itself. If the flow is correct, the first things that I would do is measure voltage across the switch or jump it out to see if this is where the issue is. If you are not familiar or uncomfortable with this checking, I recommend contacting a local service company so they can assist you.

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PentairProduct Daryl-Tech,
Posted

PentairProduct Daryl-Tech,
Thank you for your response. I have another pressure switch that I can try. I had replaced it last year, but the switch was not my problem previously. So, I am sure the old switch is good.

Also, I opened the back cover plate on the inside of the heater to expose the ignition module. The LED on the diagnostic indicator of the ignition module flashed one time when I turned on the heater. One flash indicates an air flow fault. So, the pressure is possible. I will change it and respond.

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PentairProduct Daryl-Tech,
Posted

PentairProduct Daryl-Tech,

I replaced the pressure switch. This did not fix the problem. The DDTC reads "---" for several seconds, then reads the water temperature for 1 second and then reads "OFF". It then cycles back through the same sequence and repeats.

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PentairProduct Daryl-Tech,
Posted

PentairProduct Daryl-Tech,
After it cycled through the above sequence several times, it just reads "OFF".

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Cycling through the boot up
Posted

Cycling through the boot up sequence would be indicative of something else. I am not a fan of just replacing parts and would recommend you check the voltage through the circuits. Cycling typically indicates a short somewhere and the best course of action at this point would be to remove the pressure switch wires, ensure you have 24VAc at the incoming wire and slowly start adding items back onto it to see if the switch is actually closing or if the cycling comes back. Easiest thing would be to call our team at 1-800-831-7133 and we can walk you through it.

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Daryl-Tech,
Posted

Daryl-Tech,
I removed the pressure switch wires and checked the voltage as suggested above. There is no voltage reading (-0-) to the switch. What next please?

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Daryl-Tech,
Posted

Daryl-Tech,
I have some additional information. I retested the voltage with the thermostat set high enough so the heater would turn on. Then, I heard a click and the voltage jumped to about 15 VAC for about a second. About 5-10 seconds later, I heard another click and the voltage rose very slightly to maybe 1 VAC and it went back to zero immediately. Every 5-10 seconds, I would hear another click and the voltage would be about 1 VAC and then immediately back to zero.

I then put back together and tried the heater again and the blower started on high speed as it should and then went to low speed as it should, but it would never light. I then turned it off at the power switch for 1 minute and tried again. This time it would read "---" on the display, then the water temperature for a second and then "OFF". This kept repeating as described above.

Please tell me what is the problem. Thanks in advance.

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The fact that you are only
Posted

The fact that you are only receiving 15VAC to the pressure switch and at that still seeming as though it is cycling, would mean we now need to go backwards checking the voltage out of the transformer and to the control board. If we receive the correct 24VAC and still the unit cycles without the pressure switch attached, the issue would most likely be with the board itself.

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If you are seeing "---" or
Posted

If you are seeing "---" or off on the display, I would lean towards the thermistor or a problem with the board. You can sometimes fake the board out by disconnecting the thermistor and lick your finger and hold it across the terminals where the thermistor goes and see if it comes on. If the unit comes on, then you have found your issue.

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Can you explain exactly what
Posted

Can you explain exactly what to test and how to check the voltage from the transformer ?
Should the pressure switch wires be disconnected ?

Thanks.

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I called into your office and
Posted

I called into your office and learned about testing the voltage coming from the transformer. It reads 26 VAC, which is good. Then, I tested the voltage from the control board and it read zero. So, I just ordered a new control board. Thanks for your help.

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Just getting back to my
Posted

Just getting back to my heater problem after a couple months away
. The blower switches on but no ignition. Have an E04 error code.

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Richard's picture
Tech, Pentair
You will need to check the
Richard's picture
Tech, Pentair
Posted

You will need to check the resistance on the ignitor on 200k and you should have a reading of 10-20 ohms on a new style ignitor or 50-70 ohms on the old style. If this checks out, you will need to check the voltage going to the ignitor which should be 80-120vac during a start up cycle.

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Thank upi, I will give that a
Posted

Thank upi, I will give that a try

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I now have replaced the
Posted

I now have replaced the control board (first replacement was defective) and now I only get "OFF" on the display. I no longer see the pool temperature or cycling back and forth. Just "OFF". I also replaced the ignition module. Still, just "OFF" on the display. Any suggestions?

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I had replaced the thermistor
Posted

I had replaced the thermistor probe only a few months ago. This was the first thing I tried to fix the heater.

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Daryl-Tech,
Posted

Daryl-Tech,
Please comment on what the problem is. Based on troubleshooting with Pentair, the control board was suppose to be the culprit. Now, there is no longer any cycling and the pool temperature is not shown.

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Mark,
Posted

Mark,
What is the resistance reading of the current thermistor? OFF could be just a matter of the unit not recognizing the call for heat and now that the board is no longer cycling, let’s go ahead and just double check this even if it was just replaced.

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Do you want me to unplug it
Posted

Do you want me to unplug it from the control board and measure the resistance with the heater off? Or please explain. Thanks,

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Yes, in order to test the
Posted

Yes, in order to test the sensor, it needs to be disconnected from the control board.

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The thermistor resistance
Posted

The thermistor resistance that is currently installed is 2400 ohms. The old thermistor read 1800 ohms.

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Then you would still have an
Posted

Then you would still have an issue with the sensor. We are expecting a resistance reading anywhere from 5-15K Ohms. 2.4K Ohms is well about the maximum set temperature of 104.

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OK, I will replace it again
Posted

OK, I will replace it again and get back with you.

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If the thermistor is the
Posted

If the thermistor is the problem, then why no error code?

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You could still be within the
Posted

You could still be within the parameters of the sensor. For instance, the sensor could be reading a temperature of 105 for example and not through a “HI” error code because this is a believable reading and the heater would never fire and display “OFF” because actual temp is higher than the set temp.

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Tao's picture
Just wondering if you have
Tao's picture
Posted

Just wondering if you have fixed your problem. I have the similar problem. The only difference is I will get E02 code and read light on "service" after about 10 minutes.

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Tao,
Posted

Tao,
Be sure to look at your other post here: http://poolfyi.com/forum/minimax-nt-e02-code

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I just received another new
Posted

I just received another new thermistor. I tested the resistance without installing it, and it also reads 2400 ohms. Is it also defective? I don't see much point in installing it if it is supposed to read at least 5000 ohms. How is it possible to receive two defective thermistors? I contacted Pentair about the one I purchased in July and was told it only had a 30 day warranty and so I had to buy another one, which has the same same low resistance reading.

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Tao,
Posted

Tao,

Did you get your problem fixed. I am very frustrated at this point and about to give up with trying to fix it myself. After replacing several parts (including two control boards) based on advice from Pentair, I still cannot get the heater to fire. It just continuously reads OFF and no longer displays the temperature of the pool. It think it has to be something simple, but I just don't know what could be causing this problem and it doesn't seem that Pentair understands it either.

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2400 Ohms is still too low of
Posted

2400 Ohms is still too low of a reading. Although likelihood of receiving multiple sensors bad out of the box is low, if these readings are correct, the sensor would in fact still be faulty. I suggest testing the sensor with a different meter to ensure proper function of the original meter and also if needed, test the sensor in store to be sure of operation before you purchase it. I understand your frustration and if you need to have a local company out to assist, most companies have replacement parts on hand to get you running again.

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It turned that my multi
Posted

It turned that my multi tester was not reading correctly. The actual ohm reading was good after all. I contacted a service technician who diagnosed the problem as the water pressure switch as faulty. Also, one of the temperature limit switches had to be replaced as well. The heater would then fire but not stay lit. It always trips about 3-5 seconds after lighting. I called the technician back and recommended to replace the blower because it was not drawing sufficient air to pull enough vacuum on the vacuum switch. I now have also replaced the blower, which did have a lot of rust on the housing. Again, the heater fires up, but will not stay lit. I called Pentair and was told to check the inlet and outlet manifold gas pressure. The static inlet pressure was slightly below 10" H2O. When firing, the inlet pressure drops by about 2.4" to 7.5" and the outlet manifold is at 2.1". I then gradually lowered the inlet static pressure to as low as 6.6". At this pressure, the inlet pressure drops to 4.4" when firing and the outlet manifold always stays at 2.1".

At this point, I am stuck. The heater now fires up, but will not stay lit. I have cleaned all the burners and orifices. I removed the flame sensor and cleaned it as well. Before the blower was changed, I was getting error code E04. Now, I am getting error code E05, but once today I again got a E04 code. This has been really frustrating. Any suggestions?

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For a TSI model, 2” pressure
Posted

For a TSI model, 2” pressure on the manifold side is correct but the inlet pressure should not drop more than 2” from static to running. The time that the unit cycles for could be related to the gas but also the flame sensor. If the unit cycles on/off continuously, I would further investigate the gas pressure. If the unit only cycles like this 3 times before turning itself off, flame recognition is where we should lean which would be with the sensor or module.

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That's correct it only drops
Posted

That's correct it only drops about 2.0-2.4" from static to running. What is the correct static inlet pressure? Should I increase back to 9-10"? The manifold pressure always remains at 2.1".

The heater does try to fire quite a number of times, but after it ignites it always shuts off about 3-4 seconds later. Then it cycles back through the purge (High speed fan) and the fan then drops to low speed and it ignites again. After about 3 or 4 times, I watched the display briefly flash "E04", then it cycled back through the purge and then ignited and then tripped. This continued until I turned it off. What more can I investigate about the fuel gas pressure? I already cleaned off the burners and blew air through the manifold and orifice tips. I have tried the manifold pressure from 1.6" up to 2.8", but it remains lit longer at 2.1".

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Inlet pressure needed is 6-10
Posted

Inlet pressure needed is 6-10 inches for natural gas. The maximum drop that there should be is 2 inches but you really don’t even want to have it go that far.
The fact that it will continue to attempt to fire indicates that rectification is occurring and I would attempt to dial in your pressures before moving too much further.

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Do you mean when firing the
Posted

Do you mean when firing the maximum pressure drop is 2 inches? So when firing, the maximum inlet pressure should be 4 inches, which will give me about 2 inches drop.

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If your inlet pressure is
Posted

If your inlet pressure is between the 6-10 inches static, when fired the pressure cannot drop more than 2 inches. Meaning if you start out at 9, you cannot fall below 7 when fired.

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Please explain how to adjust
Posted

Please explain how to adjust the drop when firing. My drop is always 2.2 inches. If I start with inlet static pressure of 8 inches, the inlet pressure when firing is 5.8 inches. Does this mean the valve has some rust in it and needs to be cleaned out? Or does the valve have to be replaced?

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This would be corrected at
Posted

This would be corrected at your regulator on the supply side, not the gas valve. If your supply cannot be maintained, you will experience the issue you are describing. Also, be sure of all the lights on the control board such as the high limit and T fuse. If any safety is going out we can get this as well. The primary reason for looking at gas supply though is because of the continuous cycling (more than 3 times) and that drop you’re reporting.

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I can adjust the supply
Posted

I can adjust the supply regulator from 10 in H2O down to 5 inches or lower, but I always see 2.2 inches drop when firing and the control valve will always hold 2.1 inches at the inlet manifold. What next?

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Again, I have no problems
Posted

Again, I have no problems maintaining the supply pressure between 6 and 10 inches, but the heater will not stay lit. It continuously cycles (more than 3 times), There is always 2.2 inches drop between the static supply pressure and supply pressure when firing. Also, the control valve always holds 2.1 inches at the manifold. What is the recommended fix?

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I'm having a similar issue. I
Posted

I'm having a similar issue. I realize that this post was from 3 years ago, but I'm hoping someone can still help. My system is only 1.5 years old and I would think that I wouldn't be having issues already, but I am. I'm getting a E04 error and I've checked the run capacitor on the blower already (it checks out), I'm getting 120V to the blower motor, the flame sensor is getting 90V, but the igniter doesn't seem to be getting anything. When I start the system I'm getting green lights for the Pressure Switch and Thermostat, but thats where the startup process ends. The Blower never starts, and as I mentioned above I'm seeing 90V to the Flame Sensor, but nothing to the Igniter. I'd think that I should be getting 120V going into the Igniter (the line that has the 120V sticker on it, but I'm not. Can anyone give me some advise on where to go from here? Thanks so much!

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