Pentair MiniMax NT

[Steve H]

We finally got a propane tank set and filled, and the heater is not responding at all, in talking to a local service man yesterday, he has pointed my in the direction of the 6800 mother board, going to work on cleaning it seeing if I can get back to working.it was working a couple months back but really unsure when it was run last. I will update this thread as i work to get it back up and running.

The MiniMax is on the way to being phased out so parts will eventually be harder to find.

For all of the MiniMax heater folk, below is a link for the service manual, very handy to have.

http://www.pentairpool.com/pdfs/MiniMaxNTServiceManual.pdf

 

[Steve H]

Thermistor probe is bad (open circuit), ordered new probe.

 

[Steve H]

new probe shipped on Friday should have it on Monday.

 

[Steve H]

part was delivered 20 minutes, too dark to do anything now. will work on it tomorrow.

 

[Steve H]

got probe installed and got some life into the heater, wouldn't stay lit for more than 3 seconds, voltage tests show only 6 volts at the FS terminal on the ignition module instead of 24 volts, ordered new module.

 

[Steve H]

the new ICM arrived yesterday while I was working, crossing fingers that this will fix my heater problem, I do not like chasing sparks!

 

[Steve H]

Did I mention that I do not like chasing sparks, installed the new ICM, got more life breathed into the heater, then flame went out again, rechecked all my lights, found Hi Temp light on, tested temp sensors (again) found one was bad (closed circuit), replaced sensor, got heater fired up again this time it ran longer, after several minutes I see an E05 error code ignition/flame failure, consulted service manual found the flame sensor to be the biggest problem for this error code, went back out to test and DDTC board would not turn on, had a power light but no board function started testing wire for proper voltage and managed to pull out the wire from its connector that supplies the 24 volts for the ICM and of course I do not have any connectors here with me they are all still in storage down in Tucson 325 miles away done with the spark chasing for today, gonna go got the propane tanks for the grill filled up and get some dinner made.:chef:

 

[Steve H]

I found a connector in my tool box, repaired the wire and now I'm back to the same problems, hi temp light, T fuse light, heater flame shuts down after a 3-4 second burn. contacted Pentair to see if they have a newer revised manual that supports the DDTC control board.

air temp 63
water temp 48

 

[ps0303]

Give me a run down on what parts you replaced already?

 

[Steve H]

Give me a run down on what parts you replaced already?

so far I've replaced the thermaster probe, the ICM, and one of the high temp sensors, 28 ohms on the T fuse, both temp sensors are less than 10 ohms each, cannot keep system running long enuf to check flame sensor, igniter appears to be functioning properly.

 

[Steve H]

ok found the installation manual for the DDTC control board, printed out the 3 wire diagrams I will look these over and determine which one I'm working with. I know the unit is wired with 220 volts so that will help.

 

[Steve H]

Ok, going to step back and start at the beginning, this is what I know for sure, pressure switch works, the thermostat was bad (showed open circuit on ohm meter) replaced that, it is now working. removed both temp sensors, both metered out as closed circuits on the ohm meter, returned the new one i bought on Friday as it also metered as a closed circuit, I have contacted a parts supplier to have them test their sensors before I purchase them, awaiting results.
this heater appears to have been upgraded from the 6800 control board to the DDTC control board as all of the wires are spliced, I will go through all of the wires based on the wire diagram and DDTC install instructions for proper connection, continuity and routing per the wire diagram.

updates to follow.

say did I mention that I do not like chasing sparks, did not like it when I was fixing aircraft back in the 80's

Steve

 

[Steve H]

OK, connections, continuity, and routing all good, only thing I found was the ground wire from the transformer was not connected to a ground source, it's now grounded.

will wait for the tests on the new sensors, if I like what I see I will purchase them.

 

[ps0303]

On the temp sensors, they should be closed circuits because then when they are tripped, they open thus causing the heater to stop running.

 

[Steve H]

On the temp sensors, they should be closed circuits because then when they are tripped, they open thus causing the heater to stop running.

Thanks, I review the wire diagram again, I have been thinking the opposite.

Steve

 

[Steve H]

OK So Sunday I was trouble shooting the heater, I had removed both temp sensors and the pressure switch from the heat exchanger manifold while testing all of the circuits had brought the sensors into the house, got up the next morning to the usual pool pump sound and thought nothing of it, forgetting about the parts being out of the manifold. got a text from my girlfriend saying there was water running down the street, of course it hit me about the parts, the pump was switch off by our house guest. After I got home from work I reinstalled the parts and hooked up the wires, this morning I got up to the usual pump sound and decided to turn on the heater, and low and behold it fired up and it has been on for about an hour and a half now. the best I can figure is this, on Sunday I adjusted the flow valve from 4 1//8" to 4 1/2" as per the service manual, and connected the grounding wire for the transformer, and the last factor may have been that the water may have flushed out any desbris from the exchanger, it did manage to drain about 1/4 of the pool, my cya was a little high anyway (80), going to let the heater do its job today while I'm working, I'm off work tomorrow and Thursday, so I'll test the water with the kit I have to see where it's at, and yes I have a new TF 100 kit in route (Thanks Rebecca) I will test again during the weekend after work.

so this morning I on a happy pool guy

Thanks Paul for your input.

Steve

 

[Steve H]

The good news is the heater is still working properly, the question is the pool temp is about 10 degrees cooler than the heater setting, is this normal?

Steve

 

[ps0303]

Usually the temps are closer than that. What are you using to measure the temp of the pool?

 

[Steve H]

I'm using a floating pool store thermometer, was going to go look for something better today that is more accurate, any suggestions?

 

[ps0303]

Yeah those floaters are trouble. I've used a digital meat thermometer.