Originally posted by nathan9999
dan, I don't mean to highjack this thread, but you are the first person who has responded to me on this site who (seems) to question the value of the Manual J calculation. If the Manual J shows 4.5 tons with no window coverings and closer to 4 with actual window coverings, combined with the fact that I added 6 degrees to the design temp, then why would a 5 ton be the minimum acceptable unit? Just curious.

Your statement about setting an east zone to 84 leads me to believe that you think a 5 ton unit will be undersized.

As to the zoning question, the house is a split wing with 3 distinct living areas. Zoning seems to offer a good way to meet the varying comfort demands of each zone and yet use only one unit. My experience on this site, and with the local contractors, is that most aren't crazy about zoning (although locally the ones who are against it have never done it).

My selected contractor does have experience zoning and it seems like a good option for me. My other option is to use 2 units.

I appreciate any additional insight you may be able to provide me as I make this final decision.

Thanks again.

First part is my question as well,I'd say 5 ton is oversized.But I think it's a two speed so not a lot to worry about.