Raypak 406a-en-x Heater shuts off after an hour

[Trader7111]

I have a Raypak 406a-en-x 14 yr old NG heater.
I cleaned the burners, they are free and clear and installed a new pilot.
Heater has no error messages.
After startup, mode to pool and power on, gas on. CFH appears, SPK....a few clicks, then the gas value clicks open, and the burner ignites.
All looks normal with a strong pilot flame and all burners working.
Display shows heat flame water temp 80 and set to 90.
all good.
Heater works for hours or until temp is reached.
However, sometimes, after an hour or 2, the display shows SPK and the heater/burners ar not on/working/fired up and even though the temperature has not been reached.
It seems to be timed out. Must power off wait 5min/reset, power on and heater fires up normally.
all is good.
Any thoughts on what could be the problem?
Check pressure, ground wire, pilot wire, all good.
New pilot it's brand new replaced 1 day ago, I thought this may have been the problem.

Thanks

 

[ajw22]

Sounds like the loss of flame sensing for some reason.

Let's see if @swamprat69 has ideas.

 

[swamprat69]

Looking at this manual https://www.horizonpoolsupply.com/_uls/resources/Raypak_206-406_Manual_2020.pdf and the fact that you must turn power on then off it sounds as if the circuit board is in "lockout". Display should show a fault at the time of the problem per page 29 of the manual??? Not sure of how long the display will show the fault. Possible problems may be a poor connection to ground through the new pilot assembly which would dampen the flame signal ( all metal surfaces from the pilot assembly mount back to ground must be clean bare metal ). It could also be a problem with the main circuit board/ pilot flame. Per flow chart on page 42 "system runs until call for heat ends?" / No, tells you to check ignition cable and grounding and pilot flame stability/coverage.