A/C contractor quotes - need to evaluate

[Kathy]

ceiling?

That sounds like a poor design to start with.

[Bob]

I don't design the homes, I just have to deal with them. In at least 25% of the homes in my area, the refrigerant lines are run above the drywall in the ceiling. There's one development where the horizontal air handler is hung from the floor joists in the laundry room in the center of the house. You can't stay in business very long if you insist on replacing the refrigerant lines. The next guy will insist that you don't have to.

[mad hatter®]

Rule of thumb in south Texas is 800sq ft / per ton for a/c sizing. Other parts of the country will be different.

My guess is if you had a 2 ton and now added your basement to the a/c load, you probably need a 2.5 ton. Basements usually don't get as hot as above ground so I'm thinking you don't need a lot more than what you had before. Of course I'm guessing because I don't know the location nor size of your basement but assuming the old one was doing a decent job then 2.5 should work. No need to over power the house. I suppose if you got a greater ton a/c, you could cool off the house faster if all else is sized properly. And no I'm not an expert just a guy who deals with a lot of real estate over the years in Texas.

[kck]

Madhatter, it is correct that the home had (and still does) a 2-ton unit for the lower (main) level at the time of construction. At the time of and just prior to purchase, a fifth 8" duct was installed at my request, and I was way more ignorant then than I am now. The builder did not point out the downfall of such a plan; he wanted to unload the house. As I mentioned in the earlier thread, I have never been happy with the cooling. Call me an idiot, I then added a basement and another 8" duct.

So, it appears that 2.5 is definitely called for, and perhaps 3, given the two additional demands on the original unit as explained above. Thoughts, anyone?

[HeatMan]

The houses I work in have the units in the attic, therefore access from the attic to the outside of the house.

So, the answer is yes, I run them across someone's living room ceiling, just in the attic space, not in the room.

[Tekkie®]

kck posted for all of us... I don't top post - see either inline or at bottom.

Yes, get the Manual J