Raypak heater not igniting

[toyopl]

Moved into a house that has Raypak P-R206A heater, hooked up to natural gas line.
Last year I've been having problems with it igniting, same with this year.
I need to get this sorted finally.

It will ignite, work for 15-20min, then turn off and keep igniting for next 30min, but it won't, it says Ignition failure, then it will ignite again and go thorugh same rotation again, or just keep heating for the day.
Do I need to clean something, pilot needs to be changed ?

 

[1poolman1]

Moved into a house that has Raypak P-R206A heater, hooked up to natural gas line.
Last year I've been having problems with it igniting, same with this year.
I need to get this sorted finally.

It will ignite, work for 15-20min, then turn off and keep igniting for next 30min, but it won't, it says Ignition failure, then it will ignite again and go thorugh same rotation again, or just keep heating for the day.
Do I need to clean something, pilot needs to be changed ?

Sounds like the flame sensor is bad/coated. It is the "fork" above the pilot flame. It can be removed from the heater and cleaned with a
Scotch-Brite pad or something like it. Don't use a heavy abrasive as it will remove the coating on the sensor. May have to remove the burner tray to get to it. Picture shows it upside down.