Old Lennox

No serial # on the data plate. Does anyone know how to date this unit. It still runs.

I would just mention no data available Unit is likely past design life, budgeting for a new one should be consider . Unit was functioning on the day of the inspection

If they are a matched set one can sometimes date them off the furnace date if its readable and they usually are being inside

Unfortunately the furnace has been replaced recently.
Wayne - that’s what I plan on doing.
Just by the look I’m thinking that it must be over 20 years old.