I have a 2600+ s.q. 2 story house located in NW Indiana (built in 1979) that I have owned for 5 years. It currently has a Lennox G11E-200V-4 (200k input/160k bonnet) which I think is original, plus a Goodman 5 ton Compressor replaced in 1990 (insurance-hail damage).

I am planning on replacing the furnace this summer, as I have had nothing but problems with the free-floating blower design on this monster, as well as $ 400+ monthly utility bills in the winter.

Having relatives who own a reputable HVAC company, I have the toughest part of the install process completed (finding an installer I can trust!). After running a Manual J, one of their recommendations is a Trane XV90 (120K) furnace, along with a new coil (insurance only replaced the damaged outside unit) and a liner for the chimney. After watching this site for awhile, I just have a few questions I hope someone could help me with.

1) If I'm reading the furnace tag correctly, wouldn't my current Lennox be a 80%? Was this bad boy a top of the line unit in it's day (other than being WAY oversized)?

2) What is a reasonable expectation for the life of my Goodman 5 ton? Even though it is 15 yrs old, it never has had any problems, cools well, and is fairly inexpensive to run. I don't want to replace something for no good reason.

3) The ducts currently only have manual dampers (no zoning). Is it feasible to use the manual dampers to restrict airflow to the lower lever to increase flow upstairs (acting as manual zoning), or would that be a waste of time?

Thanks in advance for your advice