Pentair Mastertemp 400 Max Temperature Setting

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R

riverscompound

Member
Dec 21, 2020
6
Lake Havasu City, AZ
Hello. I have a pentair mastertemp 400 heater and we recently had some electrical work done and the pool equipment breakers were all shut off. This caused the heater to reset to the default settings and now we can't get the spa over 100 degrees. I read a lot of the advice on the forum and know I need to reset the temp by pressing the yellow button on the control board under the cover. I followed the instructions in the manual but the display doesn't turn on when I press the yellow button and I have no way of raising the max temperature.

There is an iaqualink controller installed as well and I understand there may be something I need to do with the firemans switch wiring to engage the yellow button to reset the temp but I don't know exactly what that is. Does anyone have any advice on this and what I need to do to get that yellow button to work?

Thanks in advance!
 
mknauss said:
Welcome to the forum!
Is the heater direct wired to power or through a relay? It needs power to it for the process to raise the max temp to work.
I suggest you read ABC's of Pool Water Chemistry.
Click to expand...
I don’t know if it is direct wired or through a relay. It turns on and off through the iAquaLink system so if that’s what you mean then it would be a relay. Is there something specific I can look for to determine?
 
I suspect it is through a relay. You would need to activate that relay (should be your normal Pool Mode) and then see if the heater responds.

If not, you might have to jumper the Firemans Switch. I would like to ask @JamesW for his input prior to you going that far.
 
Set the desired temperature in Aqualink to be higher than the pool water temperature and that should turn the heater on.

What is the current water temperature displayed in Aqualink?

What is the desired temperature set in Aqualink?

I don't think that you will need to do anything with the yellow button.

Press the Pool On or Spa On button if the display does not come on.

See what the temperature is on the display and then press the up arrow to set the temperature to a few degrees higher than you will want to heat the water.
 
See page 37 in https://www.pentair.com/content/dam.../heaters/Manual-MasterTemp-472592-English.pdf

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com www.troublefreepool.com

Maximum Temperature Set Point
The heater comes factory set with a maximum temperature set point at 78° F (25.6 c). for the pool mode and 100° F (37.8 C). The Installation Manual describes how to increase the maximum temperature set point of the pool and spa. It involves unbolting and removing the door panels, accessing the control panel board on the underside of the top cover, and locating the yellow button on the corner of the control board.

Pentair MasterTemp Maximum Set Point.PNG
 
Allen - his first post stated he tried that process but the heater did not power on. The heater needs power to follow that process.
 
mknauss said:
Allen - his first post stated he tried that process but the heater did not power on. The heater needs power to follow that process.
Click to expand...

I missed that. I would try some contact cleaner around the yellow button. If the yellow button does not trigger the reset logic then he has a board problem.

I would pull the board and look carefully for any flaws around the yellow button.
 
JamesW said:
Set the desired temperature in Aqualink to be higher than the pool water temperature and that should turn the heater on.

What is the current water temperature displayed in Aqualink?

What is the desired temperature set in Aqualink?

I don't think that you will need to do anything with the yellow button.

Press the Pool On or Spa On button if the display does not come on.

See what the temperature is on the display and then press the up arrow to set the temperature to a few degrees higher than you will want to heat the water.
Click to expand...
JamesW said:
Set the desired temperature in Aqualink to be higher than the pool water temperature and that should turn the heater on.

What is the current water temperature displayed in Aqualink?

What is the desired temperature set in Aqualink?

I don't think that you will need to do anything with the yellow button.

Press the Pool On or Spa On button if the display does not come on.

See what the temperature is on the display and then press the up arrow to set the temperature to a few degrees higher than you will want to heat the water.
Click to expand...
No matter what temperature we set the aqualink to or on the heater display controls, the spa never goes over 100 degrees. It will turn on and off and maintain temp but will never go over the default 100 degrees. My question is how to bypass the automation wiring so that something happens when I press the yellow reset button to raise the max temperature
 

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Is the Pool On or the Spa On light lit on the heater?

What happens when you press the up arrow?

If the Pool On light is lit, press the Spa On button and then press the up button to increase the temperature setting to 104.

Is the water temperature reading correct from the heater and the Aqualink?
 
JamesW said:
Is the Pool On or the Spa On light lit on the heater?

What happens when you press the up arrow?

If the Pool On light is lit, press the Spa On button and then press the up button to increase the temperature setting to 104.

Is the water temperature reading correct from the heater and the Aqualink?
Click to expand...
Yes the Spa light is on and the heater works as expected. The only thing it does is max out at 100 degrees instead of whatever I set the temperature to. Even if I set it to 102 on the control panel on the heater or the aqua link. It is just defaulting to the factory settings of 100 degrees for the spa. I know I need to adjust the max temp setting by following the steps in the manual. I am just getting stuck at the reset button step.

All I need to know is how to bypass the automation wiring and get the unit to respond to my reset button.
 
You can jump the fireman's switch terminals together.

Make sure that you understand exactly what you're doing before you do it.

Do at your own risk.

Pentair_MasterTemp_Firemans_Switch.jpg
 
The fireman's switch should go to the automation where a switch closes when the automation wants the heater to turn on.

So, you just jump the two terminals together to do the same thing.
 
riverscompound said:
Even if I set it to 102 on the control panel on the heater or the aqua link.
Click to expand...
Can you set it to 102 on the heater control panel?

If it's set to above 100 in Aqualink, then the fireman's switch should be closed all the time.

We are missing some important information that we need to understand exactly what's happening.

The heater should be powered all the time and not through a relay.

Maybe have the electricians back out to check everything if you can't get it figured out.
 
You can try putting the AquaLink in Service mode and then pressing the heater button to activate the heater.

What is powering the heater, is the power supply going through a relay?
 
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