Pentair Max E Pool heating issue


Aug 7, 2022
Check the stack flue temperature with the thermal regulator in and then out.

While running, press and hold the On button will display the exhaust temperature display.

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 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, and then flashes to 40, then back to 80, and 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.

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If you undo the union, this part will unscrew so that you can get a better look into the inlet.

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Maybe the heat exchanger is scaled on the inside or sooted on the outside.
thank you for this information, I'm having trouble getting the heater to ignite right now without the service light coming on.

Before the service light comes on the heating light blinks and blinks, the digital temp goes from 80 to 180 to 0 and 80 flickerings constantly.

I will check the rest of the items you listed.


Aug 7, 2022
Is that before or after the heater lights?

Maybe a bad temperature sensor or a bad board or maybe no water flow.
This is before the heater lights, when it does heat which was the other day I just remember seeing and feeling the burning water coming out of the jets. Almost like a haze, I immediately turned it off and heard a banging noise. It seems like this heater is all sorts of issues at this point.

the person who replaced the regulator last time said it may be my board as well but hasn't had a chance to actually come diagnose it.


Aug 7, 2022
You might have a lot of DE clogging the heater tubes and preventing good flow.

Is this an in-floor cleaning head?

If yes, is it working correctly?

Is there an inline strainer?

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good call, I saw a small leak coming from the 2" cap above that. I was able to clean it out, it had a broken metal strainer with a lot of DE and small pieces of broken plastic from the mesh filter. Fortunately, the pool jet's pressure was able to build back up but only for a short while until it got clogged again with DE.

I guess the first step here is to replace the mesh filter first within the water filter unit so it can stop backflowing the DE and whatever else into the tubes. Maybe this will resolve the pressure, and hopefully also resolve the heater issue.

Maybe the filters have been deteriorating for a while now, and the backwash has been happening slowly. I'm a bit upset my pool guy didn't catch this earlier, he actually didn't even catch it until I asked him.
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