Old Reznor XL45-5

[Lucenut]

I have an old Reznor XL45-5 a buddy got for my garage and hooked up a couple of years ago. He put on a whole new gas valve. It worked great for 2 years. Now I can light the pilot, turn the thermostat on to call for heat. The burners light for about 10 minutes, then the whole valve shuts off, pilot and all. If I turn the thermostat off and light the pilot it will stay lit. So that makes me think it's not the thermocouple, but maybe the high limit switch. There is also an "eco switch" that I don't understand. I can't seem to find a wiring diagram.

Thoughts? Should I just try replacing the high limit or eco switches?

 

[nadogail]

IMHO, I once took an HVAC Basic Skills Course, you should make an effort to contact Reznor and get some documentation before you begin to "throw parts at it".

What do you plan to do with the parts that you replaced that did not solve your problem?