How can I tell what size A/C unit my house needs?

I am buying a new home and the builder installed an A/C unit that is smaller in size than others in the neighborhood.


The house is 3650 sf, and the A/C unit is 13.0 SEER and according to the manufacturer's website (Ducane) the unit has a 1.5 to 4 ton nominal capacity. I spoke to a guy that used to design HVAC systems and he said that for a house that big, I'll need 5 tons of cooling and there should really be 2 separate 2.5 to 3 ton each units.


Any help would be greatly appreciated.

How can I tell what size A/C unit my house needs?
you do not need 2 seprate 2.5 ton units he is trying to make money off you big time cause you will be paying to have another curict installed into your breaker box. go ahead and call sears or go to there web site and they will help you alot more then that guy you spoke to please watch who you speak to i have work in the ac field and due to all the jobs i went on after people wasted there money on something they did not need i got out of the hvac field but i do it on the side if some one calls me to coem over and speak to them about it
Reply:It should be okay. Of course it depends if you are in an extremely hot climate or not. Just run it and see if it cools properly. It is summer. Some HVAC guys always want to over capacity every thing.