Sta-Rite Max-E-Therm 400 heater

JohnDib

Member
Apr 18, 2020
13
TX
I have a Sta-Rite Max-E-Therm 400 heater for my Pool&Sps. When I turn it on, it works good. Once it reach the set temperature, it will stop as it is supposed to. When the temperature drops below the set temperature, it will start again, however, sometimes, the heater will not start and giver “E05” error in the screen. Is this a problem with the stack flue sensor and need replacement.

Thank you in advance for your advise. Appreciate it.
 

JamesW

TFP Expert
Mar 2, 2011
22,037
While the heater is running, press and hold the On button until the stack flue temperature is displayed and see what that is.
 
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JohnDib

Member
Apr 18, 2020
13
TX
While the heater is running, press and hold the On button until the stack flue temperature is displayed and see what that is.
OK. Which one should I hold, Spa or Pool; or doesn’t matter.
Also, what should I expect to see, normally.
Thank you
 

JohnDib

Member
Apr 18, 2020
13
TX
Whichever is on. If pool is on, press and hold the "Pool On" button.

Should be about 300 degrees.
Hi James,
I did start the heater today, and when I started it,
And I did press and hold the "Pool On" button. The temperature was 160 and started going up to 200+, the changes back to water Temp.
Thank you.
 

JohnDib

Member
Apr 18, 2020
13
TX
Hi James,
I did start the heater today, and when I started it,
And I did press and hold the "Pool On" button. The temperature was 160 and started going up to 200+, the changes back to water Temp.
Thank you.
More info, today I opened the heater and cleaned it and unplugged /then plugged the sensor after cleaning the dust. I also want to say that after starting the heater, the temp went up to 92, the target temp, the heater stopped. Then when the temp started to go down, the Heater started again with no problem. Waited 3-5min, the E05 code did not appear. I Turned it off.
 

JamesW

TFP Expert
Mar 2, 2011
22,037
Press the Pool On button to start the heater.

Before the heater even fires, press and hold the Pool On button to make the stack flue temperature display. Note the reading.

It will go back to water temperature as before.

Wait 5 minutes to allow the heater to get to full temperature and then press and hold the Pool On button again until the stack flue temperature displays again. Note the temperature.

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

JohnDib

Member
Apr 18, 2020
13
TX
Press the Pool On button to start the heater.

Before the heater even fires, press and hold the Pool On button to make the stack flue temperature display. Note the reading.

It will go back to water temperature as before.

Wait 5 minutes to allow the heater to get to full temperature and then press and hold the Pool On button again until the stack flue temperature displays again. Note the temperature.

The stack flue sensor may be tested with an ohm meter (3.8 MegOhms @ 77F).
thank you James for your help
Before the heater even fires, I did press and hold the Pool On button and the stack flue temperature displayed 40 then 80 then 40...then 80
5 min after the heater started, the stack flue temp displayed 271-273.
Please advise. Thank you
 

JamesW

TFP Expert
Mar 2, 2011
22,037
The alternating 40/80 usually means the the circuit board is not getting a good reading from the stack flue temperature sensor.

Check the stack flue temperature sensor with a good ohmmeter while the sensor is cool. It should read 3.8 megaohms.

Check the wires from the circuit board to the sensor to make sure that they are not damaged.

I would replace the sensor if the wires are good.

If it still has problems, replace the circuit board.
 

JohnDib

Member
Apr 18, 2020
13
TX
The alternating 40/80 usually means the the circuit board is not getting a good reading from the stack flue temperature sensor.

Check the stack flue temperature sensor with a good ohmmeter while the sensor is cool. It should read 3.8 megaohms.

Check the wires from the circuit board to the sensor to make sure that they are not damaged.

I would replace the sensor if the wires are good.

If it still has problems, replace the circuit board.
Thank you again. Will check these next week.

I do have a question. How do we check the wires from the circuit board to the sensor to make sure that they are not damaged.

have a great evening. Thank you
 

JohnDib

Member
Apr 18, 2020
13
TX
The alternating 40/80 usually means the the circuit board is not getting a good reading from the stack flue temperature sensor.

Check the stack flue temperature sensor with a good ohmmeter while the sensor is cool. It should read 3.8 megaohms.

Check the wires from the circuit board to the sensor to make sure that they are not damaged.

I would replace the sensor if the wires are good.

If it still has problems, replace the circuit board.
James. I want to thank you for your help and advise. I did check the stack flue temperature sensor with a good ohmmeter And it was not working. I did replace it and the heater worked good. Thank you
 
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