Pentair mastertemp 400 heater stops heating after a while

[Dr.Ron]

Hello. My 2 year old (or so) heater works fine but then it stops heating and I get the red light service heater.
If I shut the heater down and then restart it, it fires up but eventually stops heating.
At first I was only turning it on/off right at the heater. Then I made a program on my inside Jandy panel to run and stop the heater daily. It seemed fine for a couple of days but the we noticed the pool wasn't as warm as it should be. There are no error codes. I did check the back of the panel and there were no error lights, although I did not do this while the service heater light was on. I guess I should do that. Does this sound familiar? Control board issue? Thermoregulation? Hoping for some guidance and a cheap and easy fix. I had a pool guy here today and he was stumped! And he's their heater specialist.
Thanks in advance!
Ron

 

[ajw22]

I did check the back of the panel and there were no error lights, although I did not do this while the service heater light was on. I guess I should do that.

Yes you should.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Does this sound familiar? Control board issue? Thermoregulation? Hoping for some guidance and a cheap and easy fix.

Check and test the thermal regulator.

 

[Dr.Ron]

I tested the thermoregulation and it's fine. The heater is running fine since the pool guy disconnected it from automation. They told me the control board needs to be replaced.
I'm thinking of trying the Amazon boards since they're 25% the cost of an OEM one or even less! Plus amazon takes everything back

Yes you should.

Pentair MasterTemp Heaters - Further Reading

www.troublefreepool.com

Check and test the thermal regulator.

Also, he disconnected the automation wires. I see them inside the unit but I'm not sure where they go to get plugged back in after it's fixed. Can you show me where they go? I see 1 spot with nothing attached on the top in the pic, but there are 2 wires to be reconnected. Thanks.

 

[ajw22]

Replace the control board in the heater or the automation?

What automation? Your signature does not list any...

43,500 gallon Gunite pool with spa attached w/ spillover, Salt cell, 3 waterfalls & sun deck.
Jandy DEL 60 filter, Jandy 2 hp pump, a blower for the spa, Polaris 250 cleaner with a separate pump, 1hp Jandy pump for the waterfalls.

Disconnect the yellow jumper and connect the control cable to the two terminals...

 

[Dr.Ron]

By automation I assumed he meant where my inside control panel I can use to program the heater to go on/off set days/times.
So he added that jumper, got it. Does it matter which wire goes to which terminal? I assume no.
Replace the control board in the heater. He disconnected that cable and the heater has not shut off before reaching the set temp since.

 

[ajw22]

By automation I assumed he meant where my inside control panel I can use to program the heater to go on/off set days/times.

Show us a picture of your control panel.

So he added that jumper, got it. Does it matter which wire goes to which terminal?

No. No polarity on that connection.

Replace the control board in the heater. He disconnected that cable and the heater has not shut off before reaching the set temp since.

If the heater is running normally without the automation connection then I doubt the problem is with the heater board.

If the problem was in the heater it would show the problem when running stand alone.

 

[Dr.Ron]

I guess he figured with that connection it's a problem with the board since there was no other error codes or lights. Do you have any suggestions? I can't post a pic of the panel until later.

 

[ajw22]

I guess he figured with that connection it's a problem with the board since there was no other error codes or lights. Do you have any suggestions? I can't post a pic of the panel until later.

He did not do any real diagnostics. He is just guessing and throwing parts at the problem.

He did the right step of disconnecting the heater from your Aqualink to isolate if the problem is in the heater or automation. But there is no smoking gun pointing to the heater as the problem.

When the heater shuts down prematurely a multimeter should be used to check the continuity of the heater relay on the automation.

If the heater relay is open then the automation told the heater to stop and the problem is with the automation.

If the heater relay is closed then the automation is commanding the heater to run and if it stopped the heater did it on its own.

That simple check may take 10 minutes when the heater shuts down if you know what you are doing.

And then if the heater is doing an uncommanded shutdown it is more likley one of the safety sensors then a defective board.

 

[Dr.Ron]

Not my panel but the same one that I have. I'm leaning towards just leaving everything as is since the heater is working just fine. I'd just have to walk out to the heater to turn it on/off everytime I want it on or off.
Funny thing is that until I set a program to turn the heater on/off daily on the panel in the pic which is inside my house, I never had a problem.
Could it be just that the Jandy panel and the Pentair heater don't "talk" well?
Thanks again!

 

[ajw22]

Could it be just that the Jandy panel and the Pentair heater don't "talk" well?

They talk fine.

I had a Jandy Aqualink with that panel and a MasterTemp heater for many years.

Like any electronics as the Aqualink ages it can get quirky.

 

[Dr.Ron]

The tech said he was non the phone with pentair and based on what he told them, that's what they said was the issue...the board.
Anyway, they quoted me a laughable $860 for a new board. I can change it myself in 10 min.
It is working fine right now so I think I'll just leave it as is.