Lennox recommended a pressure test on pulses every three years as part of their maintenance routine.
By doing the pressure tests for free, when they find a bad HE, the contractor gets to install a new furnace for the price of labor. The company I worked for charged $1750 three years ago when I was there. This did include the new warranty.
If it is not the original owner, then the furnace is not covered under the warranty and the HO pays full price for a new furnace.
Between pulses and the dura-curve heat exchanger, I loooved Lennox! It made me a lot of money on my incentive checks!
The shop I work for has in writing that the second owner gets 20yr warranty on a G14. Original owner lifetime. If that furnace is less than 20yrs old and you're the first or second owner I would get that thing pressure tested ASAP. Being the fact that it is a G14 it is probably getting real close to that 20 year mark, or it maybe already past???
Hey you guys are right it is a g14,we got this pulse for our showroom in 92 or 93 ,I thought it was a 21.I installed it in my house in 99 ,pressure tested last year all ok.Now we are getting a g71 for showroom and g61 coming to my house.that flex really stopped the rumble coming up the R/A