I currently have a Lennox Furnace (G51MP-48C-110-01) in my home, and a Carrier AC unit (split system). My AC is going out and I'd consider using the tax credit to get an upgraded AC unit. Manual J estimates a 3.5 ton AC. Problem is, I'm confused as to how I would qualify for the tax credit. I called the IRS and it appears that the language in the tax credit has not been clearly defined (nor may it ever be). The IRS rules say that an AC unit can be installed by itself "as long as it qualifies on its own." I'm told that the AC and furnace together define the SEER/EER ratings so I'm not sure how to tell if the "AC qualifies on its own." To make things worse, it looks like my furnace is a commercial unit, so looking it up has been difficult. As an example, the Trane site requires Furnace & AC model numbers to print a certificate. Dealers in the area are as puzzled as I am.
Can anyone shed some light on this? Better yet, has anyone gone through this process and could possibly suggest some working combonations, or how to mix & match? Can I just buy a 3.5 Ton unit and use the AC's specs?
Any help would be appreciated.