I am considering bids from three contractors regarding complete replacement of my A/C and heating in Houston, TX townhouse. The inside equipment will be in the attic, which is typical for this area. The original equipment installed when the home was built was supported on the attic floor.
Two of the contractors propose installing the new equipment on the floor like the original system was installed.
One proposes suspending the new furnace from the rafters.
Both camps claim that their installation method will reduce noise into the house. All three offer a Lennox G60V (this is Houston, remember--not so cold in winter, so the G61V is not really worth it), which is supposed to be about as quiet a blower as you can get. Since even my current 25-yr-old Magic Chef isn't audible in the living space of my house, I'm really not too concerned about noise coming through the floor.
Unless I've missed a thread, I've gathered that as long as the install is done competently, both methods can be acceptable. Do I have that right?
I'm a little skeptical of the roof mount. I don't know how to judge the integrity of the truss system, and don't know if it could be compromised by hanging a few hundred pounds off it. Since I haven't had a rafter-mounted system before, I don't know if that might introduce sound to the house where there wasn't any before.
The floor-mount guys also say that rafter suspensions introduce the risk of metal fatigue at the gas line connection, if the furnace vibrates or sways. Is that a real concern, or just scare tactics?