igniter issue h250ed2

[johnny5]

Hello everyone
Have been reading and hopefully can get a few answers from you guys.
I have an in ground spa controlled by a hayward H250ED2. It is doing the customary light then go out 4 seconds later, then giving IF fault code. I have changed igniter, same issue. I have changed control board twice, same issue. The two control boards were used but looked in good shape. I removed manifold header and found stuck thermostat.
waiting for replacement, I removed to test without and again still have same issue. From my research done I don't see anything else that can cause this issue. Just wondering if anybody has some idea or answers to this. I was wondering if gas valve could cause.
It gets its 24 v when temp demand and loses 4 or 5 seconds later so do see issue but I'm grasping now.
All safeties are good and temporarily bypassed to check.
but if I understand correctly it would never attempt to light if any were bad anyway. Any suggestions would be greatly appreciated.
Thx.

 

[ps0303]

The sensor wouldn't cause it to go out after 4 seconds. I would look at the unit when it tries to light and see what the flames are doing? The only other thing that can cause these symptoms is a sooted up heat exchanger. When this happens, the unit lights and the flames roll around under the heat exchange thus causing the system to shut down. Check and see if it's sooted up.

 

[johnny5]

Will do thank you for the help.

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