Parts list for Lennox GCS20R-411-100

[etctaylor]

Looking for a parts list for this 1994 packaged unit. Specifically the lennox part number for the natural gas orifice.

[cjpwalker]

While you won't get that information here due to the no DIY rule, I am curious as to why you need a gas orifice - it is not something that commonly fails...

[etctaylor]

It is a natural gas furnace that was previously converted to propane. I am converting it back to natural gas. I purchased a conversion kit that changes the gas valve back but I also need to change the orifice back. I don't know who did the previous conversion or if they modified anything but the gas valve. The gas valve has the sticker that it was modified. Also, the gas company required that I have a licensed gas plumber connect the unit to the meter. I paid him $ for that and he said that all that was necessary was to turn this screw on the valve, which supposedly he did. I didn't feel that confident that he knew what he was doing, despite being licensed. I looked up the gas valve info and he was referring to the cap screw that covers the regulator adjustment screw. The valve actually has to have the adjusting screw and spring replaced IAW the gas valve conversion kit instructions and the furnace service manual. The furnace service manual states to change the orifice, but doesn't give the part number. There is also a burner restrictor plate that I will have to remove if it was installed in the previous conversion.

[beshvac]

Should call an HVAC contractor. Proper orifices need to be put in and more than "turning a screw"

[pecmsg]

Sorry you wasted your time and money but live and learn.
Contact a Lennox dealer, explain to him what you need. Let him do the conversion and a combustion analysis on start up. Might as well have him go they the entire unit while he's there.