I have a Trane paid to have it installed. Zero issues for 5 years now. Bills went way down. The old one was 17 years old and starting to nickle and dime me, in addition to the high electric bill, lol. So we decided to preemptively replace it on our schedule rather than have it crap out in the middle of summer and a 2 month waiting list.
I think 3.5 ton is way too big for that house. You will short cycle the AC cycle and not be happy in the summer. My almost 1900 square foot 2 story old house in Cincinnati was very happy with a 2.5 ton unit. It was perfect for the house, but it was a well insulated tight house.
Correct - they won't cover warranty unless professional installer installs it, and then only that installer covers labor. I have had a couple Goodmans and know others that have them - none over 5 years old. They have been solid except the 4 ton I have in my new house. Installed professionally last year by previous owner. It was the top of the line Goodman - very complicated. Stay away from that. Nothing but trouble. It is computer controlled. I had trouble with it from the get go in heat mode. Had a bad outdoor TVX.
I would not hesitate to buy a Goodman from ebay. If it dies, the cost advantage is so large that it makes sense to just buy the parts if you can't sweet talk someone in covering it. Warranty is 10 years if professionally installed and its registered, otherwise 5 years if not registered. But that does not cover everything.
For my new shop I bought a 5 ton from HVAC direct - its an AirQuest. Paid $3650 delivered which I consider cheap. 14 SEER. I do all my HVAC work now.
