Pentair mastertemp 400 shutting down after hitting 289

[Hppuman]

Hello good folks at TFP,

My pentair mastertemp 400 keeps shutting down after hitting 289. It tries to start up again but tries to heat 3 or 4 times and stops. The service heater lights up and no error code. I looked at back of mother board and do not see any led lights that could indicate the problem. I took a video

 

[ajw22]

Mark you video on YouTube PUBLIC.

 

[ajw22]

Check the thermal regulator.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[JamesW]

289 is probably the stack flue temperature.

This indicates a stuck "Pool On" or "Spa On" button.

 

[JamesW]

Exhaust Gas Temperature.​

While running, press and hold the On button to display the exhaust temperature (Older Models).

The new models use the Menu to get the SFS.

Here is what the normal exhaust temperature should be:

• Below 250 degrees...very low
• 250 to 290 ..................low
• 290 to 350.................acceptable
• 350 to 480 ..................high
• Above 480...................error/shutdown.

Note: HD models can be up to 75 degrees higher. HD models use a cupro nickel exchanger and the efficiency is slightly lower resulting in less heat transfer and more waste heat.

If the exhaust gas temperature is higher then normal then water may be bypassing the heat exchanger through a broken bypass valve.

If you hold down the "pool on" button, it stays on 80, then flashes to 40, then back to 80, then the 80/40 reading and E05 indicate that the board is not getting a reading from the sensor. It's usually a bad sensor or damaged wires.

 

[JamesW]

What happens if you change to Pool On?

Does it switch back to Spa On?

 

[JamesW]

The inlet temp should not be able to get to 289 degrees.

The heater shuts off at 104 degrees and the water would boil at 212 degrees, so the 289 pretty much has to be the stack temp.

What happens if you hit the "Heater Off" button?

Does the heater come back on?

 

[JamesW]

Replace the membrane pad.

 

[JamesW]

Check the Fenwal for a solid red LED indicator, which indicates a control fault.

Most likely the heater is shutting down due to a detected stuck button error.

 

[Hppuman]

The video is public now. Thank you for responses I'll try them tomorrow and reply

 

[Hppuman]

What happens if you change to Pool On?

Does it switch back to Spa On?

It won't let me switch to pool. Seems like none of the buttons work

 

[Hppuman]

The inlet temp should not be able to get to 289 degrees.

The heater shuts off at 104 degrees and the water would boil at 212 degrees, so the 289 pretty much has to be the stack temp.

What happens if you hit the "Heater Off" button?

Does the heater come back on?

Heater off button does not work. None of the buttons work. The display shows nothing now

 

[Hppuman]

Mark you video on YouTube PUBLIC.

Public now

 

[bradgray]

Power cycle your heater if you haven't already. Best case, your membrane is sticky and it was mashing buttons on you.

If the panel continues to give you the same trouble, you may be looking at a new PCB in your future. Could be membrane only but in my experience the board goes before the membrane does.

 

[JamesW]

The membrane is definitely bad.

A bad membrane can have unresponsive buttons, stuck buttons or intermittent buttons that send erratic signals to the control board.

A bad membrane pad is a control fault and the heater should not be operated with any type of control fault.

Shut off power to the heater until the appropriate repairs can be done.

 

[JamesW]

The membrane pad is out of the correct position and it looks like it has water damage.

Has the Membrane pad already been replaced?

 

[Hppuman]

The membrane pad is out of the correct position and it looks like it has water damage.

Has the Membrane pad already been replaced?

View attachment 618675

No it has not. Original since installed in 2015

 

[Hppuman]

Now

No it has not. Original since installed in 2015

Now that I think about it. I had warranty work back in 2017 or so it may have been replaced then

 

[Hppuman]

The membrane is definitely bad.

A bad membrane can have unresponsive buttons, stuck buttons or intermittent buttons that send erratic signals to the control board.

A bad membrane pad is a control fault and the heater should not be operated with any type of control fault.

Shut off power to the heater until the appropriate repairs can be done.

Thank you I will

 

[JamesW]

Pentair Membrane Key Pad Replacement.​

The membrane keypad sometimes fails and is separately replaceable with Pentair part number 472610Z for the five button keypad used on the non-connected heater version.

To replace the membrane keypad peel the old one off, clean the area as best you can, stick on the new keypad. Be sure to align the openings for the service lights. Also, push the ribbon cable all the way through before removing the protective paper or it can get stuck to the membrane.

If a single button on the keypad is not working it may be due to corrosion on the pins of the membrane keypad ribbon cable. Cleaning any dark pins with emery cloth may get the keypad working.[38]

The following applies to the 5 button keypads found on the older MasterTemp heaters. Pin 1 is the common wire. Shorting pins 1 to 2 briefly is the same as pressing "Spa On". Pressing a button on the membrane pad shorts a pin (2 through 5) to pin 1 to make a selection. Pin 1 is the lowest pin and pin 6 is the highest pin.[39]

• 1 to 2 ...spa on.
• 1 to 3...pool on.
• 1 to 4...heater off.
• 1 to 5...down arrow.
• 1 to 6...up arrow.

You can briefly short the pins as listed above to simulate pressing a button but don't leave the pins shorted.

The pins are so small and close together that it's hard to short any two without touching the others. So don't do it if you can't short only two.

If you can short only a single pin to pin one, the board should respond as indicated. If it doesn't, then the control board is bad. If all pin combinations work by short but not by pad buttons then the membrane is bad.