[mattheag]

I just had my house expanded an additional 600 sq. ft and I bought a new American Standard (3.5 ton) unit about 4 years ago. Back then, my house was approx 1200 sq. ft. and I bought an oversized unit knowing that I would eventually expand the house. Now that I've finished the expansion I'm being told that I may need a new unit because my ceiling height is about 9 ft. I've noticed that I can barely feel air coming out of the registers in the new rooms that are furthest away from the unit (probably around 30 ft distance) but in other new rooms the air blows fine. It seems to me that if my unit were "undersized" that 1 or more of 3 things would be apparent.

1. The air coming out of the registers is not cold enough
2. The air coming out of the registers doesn't have enough cfm.
3. The air conditioner is running all of the time to keep up with the additional cooling required.

Seems like I can address option 2 by increasing the cfm (duh!). Can this be done by buying a new fan (blower?). I think my a/c guy isn't telling me something because he wants me to buy a new unit. He already quoted me one for 6K!

[Joshdta]

Sounds like you have a duct work problem not a ac sizing problem