MasterTemp 400 has stopped working. any tips?

[SlipperyPete]

Searching around, it seems like the issue could be a lot of different things. I'm hoping you guys could point me in the right direction. The warranty expired, so this will be my first attempt at a repair.

Last week, the heater worked fine. Yesterday, it started short cycling. I think it would run for 30-40 minutes and then stop heating. The heater display looked like it normally does when it's on; there was no error code. The intellicenter app made it look like the heater was working, but there was no noise and no heat.

This morning, I went out there hoping to see an error code. I turned it on and it only ran for about 10 minutes, then stopped. The "Service Heater" light is now on if I try to turn on the heater. Still no error code on the display.

The only issue I had to this point was the Stack Flow Sensor had to be replaced about 2 years ago while under warranty. It did something similar (short runs and cut off), but I don't recall if it gave me an error code.

Any guidance on troubleshooting would be appreciated.!

 

[ajw22]

Check the thermal regulator.

As a test try and run the heater without the thermal regulator.

Also check the condition of the bypass valve in the manifold.

Does your heater have a 5 button keypad or a 6 button keypad?

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[SlipperyPete]

Ok. Unless you have some quick instructions, I’ll google how to remove thermal regular and bypass valve. I’m usually pretty handy but never touched a pool heater before.

Edit: I replied from my phone initially and didn't see your link. I'll try that. Thanks.

 

[ajw22]

Try reading the Installation Manual. It shows where the thermal regulator is. The cap holding it unscrews.

Did you read through the Wiki link above?

 

[ajw22]

Does your heater have a 5 button keypad or a 6 button keypad?

 

[SlipperyPete]

See panel

 

[SlipperyPete]

Thermal regulator seems to be working just fine.

 

[ajw22]

Check the LED lights on the back of the board and the LED light on the Fenwal module when you get the SERVICE HEATER light.

 

[SlipperyPete]

As a test try and run the heater without the thermal regulator.

Also check the condition of the bypass valve in the manifold.

Without the thermal regulator, the heater fired up and almost immediately shut off and lit up the 'Service Heater' light.

I stuck my hand in to feel for the bypass valve. Everything I could reach, felt solid. But this is in a tight and awkward spot so I can't get down there to look in the hole.

 

[ajw22]

Check the diagnostic LEDs.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

 

[SlipperyPete]

Check the diagnostic LEDs.

Stupid question, but I'll need to turn on the heater for it to show the error on the LED, correct? I watched a youtube video but didn't get an answer to that.

 

[ajw22]

Yup

 

[SlipperyPete]

I finally had a few minutes to take of the panels and trip the heater. It appears my SFS (Stack Flue Sensor) is going off. Is step one to replace the sensor and see if that fixes the problem?

 

[ajw22]

The sensor is probably doing its job. You may have a broken bypass valve.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

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 than normal, water may bypass the heat exchanger through a broken bypass valve.

 

[ajw22]

This is the Exhaust Temperature I get on my MasterTemp…

 

[SlipperyPete]

My heater just cut off when the exhaust temp hit 309 on my handheld. My panel (pic in earlier post) doesn’t have an on button. I have “pool on” and “spa on”. Is it one of those that I need to hold down?

 

[JamesW]

I have “pool on” and “spa on”. Is it one of those that I need to hold down?

Yes, whichever is on.

Also, what is your coefficient of lubricity?

 

[SlipperyPete]

Also, what is your coefficient of lubricity?

I feel like this is one of those thing like telling the newb to go get the cable stretcher. lol

I'll go back and test using the buttons. I did get an E06 error just now on the display. I tested the sensor and this is the result.

 

[SlipperyPete]

Ok. I tested it holding down the "pool on" button. The numbers climbed up pretty fast. I think I first saw 180 > 250 > 330 > 400 and then the heater shutoff.

 

[JamesW]

I feel like this is one of those thing like telling the newb to go get the cable stretcher. lol

aka how slippery are you?

I tested the sensor and this is the result.

The sensor may be tested with an ohm meter (3.8 MegOhms @ 77F).

Set the meter to ohms (Red Dot).