Hello
I have a problem with a nordyn heater model #KG6RC080C-16. Fires intermittently . Replaced flame señor, gas valve, cleaned oriffices , checked outlet pressure ( 11 in. W/C ). When I remove the front burner chamber panel the unit fires almost all the time, but with the burner chamber panel closed the two burner tubes on the left fire but the two on the right where the flame señor is located are slow to light and then it goes off on flame failure. There is no blockage on the intake side. Any suggestions would be greatly helpful.

I have had this problem a few times and how I stopped it is to take the burners out and put them back in different places. This may have cleaned out the pilot channel.

Your install manual.

http://www.grandaireac.com/products/KG6RC_II_7083700.pdf

You might keep a copy for future reference.

Parts manual. You might keep a copy for future reference. This manual covers more than one model number so look at your model number before use. It also has a parts diagram which might come in handy.

http://www.batchelorsupply.com/Nordyne/Modular/GL1RA-GL1RC-KG6RA-KG6RK-KG6RC-KG6RL%20-%20Parts.pdf

One note for you. Your unit has one manufacturer but 5 different company names. Nordyne,Gibson,Kelvinator.etc with Nordyne being the parent company. Remember this if you ever need parts since the part may be available for one brand and not the other at the time you need it.