Issue with my Pentair Mastertemp 400

[JB San Diego]

Hi all. I am having an issue with my pool heater and I saw similar issues in some old threads so thought I would post here. I had a pool guy change out my thermastor and then my control board in my Pentair Mastertemp 400 (about 6 years old) trying to resolve the my issue. Basically I could not get my spa to heat above 85. I would set it on my phone to 100+ and it would just shut off at 85. Well now that I’ve spent $600 I see in the old post that the set temp on the heater must be set at 104 (it was at 85!). I have now done that and the spa is heating (so I guess I need to get my money back!). Ok so now I’ve found a second problem. It is heating but the heater shows that the temp is up to 104 and it shuts off because it has reached the heater set temp. But the controller (and my phone) say that it’s at 100…and based on my not so amazing candy thermometer, I believe the controller not the heater. Problem is the heater shuts off when it thinks it hit 104. Any way to get them more in sync? And one more question…does the system heat the pool the same way? Basically on/off and that’s hit so I need to make sure the set temp on the heater for the spa AND the pool remain at 104 all the time?

Thanks doe your help!
Jason

 

[ajw22]

The heater temperature display comes from the thermistor in the heater. The controller temperature comes from a thermistor water temperature sensor in your pipe. One of them is off.

It is probably the heater although you say your repair guy replaced it. Did he use a genuine Pentaior part? The genuine Pentair 42001-0053S Electrical Systems Thermistor Replacement Part is about $30 and the knockoffs are about half that price. The knockoffs are not as reliable.

When controlled by your controller the MasterTemp should always be set to its maximum temperature. The MasterTemp thermostat should only function as a safety and the controller should shut it down before the MasterTemp hits its temperature limit.

For a test replace the thermistor with a 10K resistor.

With the 10K resistor in place the heater should read at 76F while the Controller stops it at 100F.

If the temperature stays at 76F then you still have a problem with the new thermistor.

If the temperature drops or rises you probably need to check the wiring from the thermistor to the board, and maybe replace the board.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Temperature Sensors - Further Reading

www.troublefreepool.com

 

[ajw22]

Hi all. I am having an issue with my pool heater and I saw similar issues in some old threads so thought I would post here. I had a pool guy change out my thermastor and then my control board in my Pentair Mastertemp 400 (about 6 years old) trying to resolve the my issue. Basically I could not get my spa to heat above 85. I would set it on my phone to 100+ and it would just shut off at 85. Well now that I’ve spent $600 I see in the old post that the set temp on the heater must be set at 104 (it was at 85!). I have now done that and the spa is heating (so I guess I need to get my money back!). Ok so now I’ve found a second problem. It is heating but the heater shows that the temp is up to 104 and it shuts off because it has reached the heater set temp.

What is the heat set temperature on your EasyTouch?

But the controller (and my phone) say that it’s at 100…and based on my not so amazing candy thermometer, I believe the controller not the heater.

Confirm what temperature the candy thermometer says?

The EasyTouch and your phone get the temperature from a different sensor then your heater.

Problem is the heater shuts off when it thinks it hit 104. Any way to get them more in sync?

We need to figure out which one is off.

And one more question…does the system heat the pool the same way?

Yes.

Basically on/off and that’s hit so I need to make sure the set temp on the heater for the spa AND the pool remain at 104 all the time?

Yes

 

[ajw22]

@Jimrahbe @mknauss on this ET display the temps read SPA 100F/104F. Which is the heat set point and which is the water temperature?

 

[JB San Diego]

@Jimrahbe @mknauss on this ET display the temps read SPA 100F/104F. Which is the heat set point and which is the water temperature?


View attachment 389268

The spa water temp is 100 but it is set at 104. I believe the water is at 100 based on my thermometer I used from the kitchen (all I have at home). Issue is the heater temp says 14 and shuts off even though the ET is set at 104 but inky says 100.

 

[JB San Diego]

What is the heat set temperature on your EasyTouch?


Confirm what temperature the candy thermometer says?

The EasyTouch and your phone get the temperature from a different sensor then your heater.


We need to figure out which one is off.


Yes.



Yes

ET set for 104 but reading 100. Heater temp set at 104 and reading 104 and shut off.

 

[JB San Diego]

The heater temperature display comes from the thermistor in the heater. The controller temperature comes from a thermistor water temperature sensor in your pipe. One of them is off.

It is probably the heater although you say your repair guy replaced it. Did he use a genuine Pentaior part? The genuine Pentair 42001-0053S Electrical Systems Thermistor Replacement Part is about $30 and the knockoffs are about half that price. The knockoffs are not as reliable.

When controlled by your controller the MasterTemp should always be set to its maximum temperature. The MasterTemp thermostat should only function as a safety and the controller should shut it down before the MasterTemp hits its temperature limit.

For a test replace the thermistor with a 10K resistor.

With the 10K resistor in place the heater should read at 76F while the Controller stops it at 100F.

If the temperature stays at 76F then you still have a problem with the new thermistor.

If the temperature drops or rises you probably need to check the wiring from the thermistor to the board, and maybe replace the board.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Temperature Sensors - Further Reading

www.troublefreepool.com

Thanks for the reply. So I changed the thermastor myself with a Pentair. And the repair guy replaced the board today also with a Pentair. I can try and track the wiring what am I looking for? Is the thermastor that controls the ET tough to replace?

Jason

 

[ajw22]

Set the ET heater set point to 102. That way it is clear if the heater is shutting down due to the ET at 102 or the heater controls at 104.

Do you have a multimeter?

Remove the thermistor from the heater. Connect your multimeter to it on resistance setting. dangle it in a pot of water on the stove. Put your candy thermometer in the water with it. Turn on the heat. See if the ohms for the thermistor agree with the thermometer as the water heats to over 107.

I still suspect the new thermistor is off.

Temperature Sensors - Further Reading

www.troublefreepool.com

On the wiring you would be looking for corrosion where resistance is being added to the circuit. 100F is 5287 ohms and 104F is 5326 ohms. So poor connections in the connectors adding 39 ohms of resistance would cause the problem.

The water temperature sensor for the ET is in a hole in your pipes held on by a worm clamp. It has a long wire that runs to the ET board. It is not hard to replace once you locate both ends. But if the ET reads 100F and agrees with the candy thermometer then that is not your problem.

 

[Jimrahbe]

Jason,

Your EasyTouch display shows the 100 / 104. This means the EasyTouch thinks the water temp is 100 degrees and the set point is 104 degrees. In theory this means that the EasyTouch should still be telling the heater to heat. Is the little main panel "heat" light on?

On the heater, what is the max temp that can be set?

I like Allen's idea of setting the EasyTouch set point to 100 and see how the EasyTouch reacts. If the EasyTouch LCD shows 100 / 100 then you will know that the ET is working and that you have a heater issue. I too would assume the heater thermistor is the problem.

Thanks,

Jim R.

 

[ajw22]

Another thing to test is to see if your ET water temperature is always 4 degrees lower then the heater temperature displayed.

Let your spa cool down. Then set 99F on the ET for heater setpoint. The heater should begin running. Watch the ET water temp versus heater water temp and see how they differ when the heater starts and it heats.

 

[JB San Diego]

Another thing to test is to see if your ET water temperature is always 4 degrees lower then the heater temperature displayed.

Let your spa cool down. Then set 99F on the ET for heater setpoint. The heater should begin running. Watch the ET water temp versus heater water temp and see how they differ when the heater starts and it heats.

Thank you ALL for your help troubleshooting this! Ok I set the ET for 102. The heater set temp is 104. The spa got to 100 on the ET and the heater temp got to 104 and the system shut off. Pictures attached. Thoughts? As I mentioned before I replaced the thermastor with a new Pentair one and I replaced the board with a new Pentair as well (over the last week). I don’t have a multimeter and honestly that’s getting a little over my head. What should I do next?

 

[ajw22]

You should do the diagnostics discussed above. Posts #8 & 10.

Either buy a multimeter on Amazon or find someone who can dig into your heater further.

AmazonCommercial 4000-Count Compact Digital Multimeter, IP67, True RMS, CATIV 600V: Amazon.com: Tools & Home Improvement

AmazonCommercial 4000-Count Compact Digital Multimeter, IP67, True RMS, CATIV 600V: Amazon.com: Tools & Home Improvement

www.amazon.com

 

[Crabcruncher]

From your photo of touchpad membrane, you have a six button membrane attached to a six year old heater that came originally equipped with a five button touchpad. I assume your pool guy did that when he replaced your control board. Thanks to your photo, I researched and found out that if someone with an older heater needs to replace their control board, they also need to upgrade their membrane touchpad to the six button new version. This may explain issues others have had when just replacing their contol boards.

https://www.pentair.com/content/dam/extranet/nam/pentair-pool/residential/parts-sheets/heaters/mastertemp-max-e-therm-parts-matrix-connected-heater-update-v1.pdf