I bought this current house in 2007. At the time we bought it, we had somebody in to inspect the HVAC systems, as much of it was old at the time. The attic furnace (a Trane THS 050A 9683) had the word "crack", and arrow, and a date in March '96. Understandably concerned, the folks we had come in to look at the furnace checked it out and said the unit looked clean.
Well, today I had somebody out to repair the downstairs unit (a relatively new Goodman with a bad pressure switch) and had him do a check on the attic unit. I ask him about the "crack" notation and if it's possible it was repaired; he says the unit would not have been repairable. He peers, prods some rust with a nut-driver, shifts around, etc. He says he sees a crack, and the unit must be replaced. I, however, can't see it when I look.
Looking at where the big 'ol arrow is, it isn't even over a burner, it's to the left of the burners. And I can't see the crack, and the burner flame is a steady blue (when they are running.)
He of course quoted out a new unit.
I have somebody else coming out tomorrow to also give a quote...
My question is: If there is a crack, and if the crack is practically invisible, and not over a burner, is it even a problem? How do I know I even have a crack if it's so darn tiny? If there was a crack fourteen years ago, wouldn't that crack be a lot bigger now (so I could actually see it)? Is it reasonable to have somebody show the crack to me so I can see it before I go blow thousands and thousands on a new unit?
Lastly, the A/C units are early-90's 8-seer builder-special Tranes. If I do get the furnace installed, would it make sense to replace those now, or should I just wait until they die? (As in, how much extra work (and cost) is there to just doing the furnace and leaving the A/C alone?)