Installing an AC System | Construction and DIY projects | Forums

Awesome. That was exactly what I was thinking. I figured that it's cheaper for me to try, get everything right except for the charge, and call in a tech for the final 5%.

Thanks KVR! That's almost exactly what I was planning. The only difference is that I will only have one return. I would love to have two but for an 860sf house (eventually to be 1100) I think that one should do it. Also, it's cheaper. 

I found a really good deal on a 1.5 ton unit but it doesn't allow horizontal mounting. The manual J that I did suggested around 20-22,000 BTUs (existing size and expanded size) and the unit does 18,000. I know it seems small but I've read a lot about undersizing instead of oversizing. The common theme is that it's better for the systems to run constantly than to start and stop all of the time.

To reduce the required load I will insulate the ductwork with hard foam and add another few inches of fiberglass in the attic. 

What did you do for ductwork? I'm planning on getting rectangular rigid ducting for the trunk line, insulating it to at least an R-8, and running 8" lines to each bedroom, dual 8" lines to the living room, and dual 8" lines to the kitchen/dining room.

Awesome! Found one that'll take side mount for only $1087. Got the ducting more or less designed and just need to get it ordered and get the official quote. I'm still not 100% on undersizing (1.5 ton vs 2 ton). The engineer in me wants to go 2 ton with variable speed to be safe.