Pentair Mastertemp 400 question

cgpatterson

Member
Jul 19, 2013
9
Nacogdoches, Texas
Pentair Mastertemp 400 question

This heater is combined with Pentair EasyTouch control panel. The temperature on the control panel when in SPA mode, heater running is much higher than actual Pentair Mastertemp reading. I set max temp on unit to 104, also set EasyTouch to 104. But after running for 30-45 mins, the SPA temp on EasyTouch gets to 110-115F. Of course the heater shuts off at 104 and thus stops the heating process. At this point, the actual SPA water temp is about 90.

I calibrated the SPA temp down by 9 degrees on EasyTouch but this duck tape fix is not the solution.

Where is the heater reading its temperature? I have changed the two attached temp sensors before but maybe the one attached to the inlet pipe running into heater has gone bad? Also not sure if the heater receives its reading from this sensor or it has its own internal sensor?

ALSO...after about an hour, the heater shuts off completely but just before shows Service Heater light. Pulled the front panel of heater and no LED light on interior control panel, nor any error codes on the touchpad panel.

Thanks for your help!

in-ground 30,000 | All Pentair equip | Built in 2013 | Chem maintained and balanced | i'm sure I forgot something
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,590
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
The EasyTouch gets its temperature from the water sensor that is is in the inlet pipe before the heater.

The MasterTemp gets it's temperature display from it's internal temperature sensor thermistor.

One or both of yours could be reading incorrectly. You can test them if you have a multimeter. Read



Is this a new problem? Did it ever work properly? Your water sensor could be positioned in a bad place getting an incorrect reading. You may want to show us pics of the sensor placement and your equipment plumbing.


Pentair_MasterTemp_Water_Manifold.jpg
 

cgpatterson

Member
Jul 19, 2013
9
Nacogdoches, Texas
It has been working correctly for almost 8 years. I'll add some pics of plumbing but the pool temperature sensor is on a pipe to the right of the heater. The exhaust of heater on left side so I don't think that would be an issue.

I thought about swapping out temp sensors (Air for Pool) to see if that may be the problem.

This would cause the heater to turn off?

Thanks for your help!

The EasyTouch gets its temperature from the water sensor that is is in the inlet pipe before the heater.

The MasterTemp gets it's temperature display from it's internal temperature sensor thermistor.

One or both of yours could be reading incorrectly. You can test them if you have a multimeter. Read

Is this a new problem? Did it ever work properly? Your water sensor could be positioned in a bad place getting an incorrect reading. You may want to show us pics of the sensor placement and your equipment plumbing.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
24,590
Northern NJ
Pool Size
35000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
This would cause the heater to turn off?

The heater is controlled by the EasyTouch using what is called the "firemans switch". You set the desired pool temperature in the ET. The ET turns the heater on using the firemans switch and off when the pool water reaches the setpoint. The ET uses its water temperature sensor to determine if the heater should be on or off.

You set the MasterTemp thermostat to 104. The only time the MasterTemp will normally shut itself off under automation control is if it sees the water temperature at 104 or above. The MasterTemp heater can also have abnormal shutdowns of the heater if any of its safety systems get triggered.

 

JamesW

TFP Expert
Mar 2, 2011
23,855
Is the reading from EasyTouch accurate when the heater is off?

If no, then you probably just need to replace the thermistor.
 
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