Need a 2nd HVAC System - In Attic maybe?

[Sam Johnson]

When we had our house built in 1999, we opted for ONE high efficiency AC/Heat system in basement w/2 zones - one for each living space floor (no basement feeds). We since have added an "in-law 2-room apt w/bath" w/electric heat (OUCH!) and window AC. We would very much like to have what the builder originally recommended: a 2nd system (heat+AC) servicing the 2nd floor (4 bedroom + 2 baths) and the 2 room+bath in-law apt. The total sq. foot area to be serviced is about 1500 sq ft. Location: central NJ (agri-Zone 6). I'd like to do most of work myself (I'm in the restoration/carpentry/bathroom upgrade/etc. business and feel I can install a unit myself for the most part (except for gas line). How do I size? Do I have to worry about existing ductwork (e.g. air returns to basement system). Is the compressor always outside with freon lines to/from attic? etc? etc? AND WHERE DO I BUY SUCH A SYSTEM (of course, without the installation crew and related expenses). THANK YOU

[Mark Jones]

I'd have a couple local guys come out and look at what you have and get thier recommendations and price. Where you buy the equipment will depend on the brand you go with.