minimax nt reading off

Apr 12, 2017
6
Huntington Beach
#1
Minimax nt heater starts heating and then shuts off. Off is showing in digital readout. No error codes. It does not make it to set temp. Power is still showing spa and remote green lites also on. Heater guy came out tested and said it was circuit board. Replaced that and still same problem. Heater is hooked up to Aqualink which also shows on while heater has shut off. Any ideas?
 

CountryBumkin

Bronze Supporter
Jan 9, 2017
124
Orlando/FL
#2
Is the "AUX" light On? Can you try running the heater in manual mode (not using remote) - you would need to remove the two-wire remote wires and jumper across those connections (page 21) to by-pass Aqualink control. Does it heat properly then? It sounds like Aqualink is reading the pool water temp and telling heater to stay on, but heater is shutting it self off. It could be the "temp sensor (hi Limit switch)" in the heater thinks the water is at max temp and therefore shutting off heat. Can you remove the cover to see the circuit board (the lights on the board)? See page 35 Assuming this is the model you have) of the manual http://www.psposeidon.com/uploads/libraries/secured/fr/MiniMax-NT-Series-Service-Manualpdf.pdf

Did you pool repair guy refund you the cost of the circuit board - since he misdiagnosed the problem?
 
OP
OP
N
Apr 12, 2017
6
Huntington Beach
#3
Yes that is the model. Pool guy ran all the tests seemed puzzled there were not error codes, bypassed the board and heater fired up.I ordered new cb and installed at his recommendation. Problem is not firing up heater problem is shutting off. I was in spa yesterday, set to 99, when it needed to kick on to hold temp, it read off, with power on, heater red light showing on aqualink. And no pool heater guy has not returned recent call. Thanks
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,961
FL
#4
Since the board controls everything, bypassing it doesn't really tell you what is wrong.

Bypass the pressure switch and see what happens.
 

CountryBumkin

Bronze Supporter
Jan 9, 2017
124
Orlando/FL
#5
Just to be clear - to distinguish between an Aqualink problem and heater problem.

If you disconnect the Aqualink (jumper the remote pins/connections on the heater - or bypass AquaLink following the instruction on page 13 of the manual) will the heater stay running and maintain the proper temperature? In this test you would be setting the spa temp (99 degrees) using the heater's temp setting control.

Do you have the Aqualink RS? If so see page 13 of the manual. http://www.jandy.com/~/media/zodiac/global/downloads/0748-91071/6919.pdf
The Green light means heater is enabled, and the red light means "signal/command sent for heater to fire".

The MiniMax manual has a pretty good troubleshooting section (starting at page 29).

Is the "TSTAT" light on? Does the "Heat" light come on when the heater should be running (i.e. temp set to 99 and then spa water temp cooled down below 99 (and red light on Aqualink comes on))?

Good luck.
 
OP
OP
N
Apr 12, 2017
6
Huntington Beach
#6
Yes it is Aqualink rs. Not sure what tstat is and yes red light is on Aqualink. There was a 2 degree difference on heater temp and
aqualink reading in house while heating. Does that make a difference? I will look in manual and see what gives. Thanks for info from all.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,961
FL
#7
On this unit, if you press the "remote" button and the LED goes out, you can now control the unit independently from the RS system. No need to disconnect any wires but if it makes you fee better, go ahead and do so.

Also "OFF" can be displayed if the heater has an issue with the thermistor.

On this unit you have the following LEDs that display on the front panel left, Power, Pressure Switch, Thermostat, Heating and Service. "TSTAT" is for the older non digital Minimax system. The one with the dials.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,961
FL
#9
I was kind of hoping you would try it and then let your pool guy know he isn't as knowledgeable on pool heaters so maybe he shouldn't try fixing them. Way too often I hear about the "pool guy" who tries to fix a pool heater only to not have the knowledge of it. I would highly suggest that you find a qualified licensed person to do the work on it.
 

ps0303

TFP Expert
In The Industry
Jul 6, 2011
3,961
FL
#11
Your post before this current one you said you were going to have your pool guy look at it. So what was done to the unit to rectify this issue?
 
OP
OP
N
Apr 12, 2017
6
Huntington Beach
#12
He is now coming out next week and is a heater guy. I mentioned earlier some of the things this thread mentioned and he said possibly pressure switch. It has the new circuit board. And also as mentioned no error codes have showed up and filter recently cleaned.
 

mktsjb

New member
Apr 11, 2009
4
#14
I'll put odds on the thermistor.
One problem that causes this is when the temperature water sensor is defective. Not the thermistor for the heater, but the water sensor pentair 520272. This sensor when not working properly will confuse the heater and the heater will start the fan but then turn off on the display with no error code...