I am purchasing a new GFA furnace and central air to replace my 20 year old unit. The question that has arizen is to go with a 3.5 ton air conditioner (my current size) of size down to 3.0. My HVAC person tells me if we sticke with the 3.5 they will need to do some special fitting of the units because the furnace is 21" and the evaporator coils on the air conditioner are 24". He claims they do this all the time. Anyone done this? By the way I'm in upstate NY and my home is 2450 sf. I took the survey that the EPA has and it says i need less than average for a house my size.