"yaofeng" wrote in message
oups.com...
No. This guys has his business in our town and has been in business
for 35 years. He takes out about 1,000 permits a year. He did most of
the houses in my neighborhood. Actually one of my neighbors gave me
his number. He probably did the existing AC before I moved in the
house in 1990.

In addition to pricing, I am prejudiced because I like him. He
explains how things work to you.

I'm going to buck the experts here. Forget the Manual J.

In a new house, new design, I'd agree 100% that the Manual J calculations
should be done. If, however, you'll lived in the house for 15 years, it has
been very comfortable with a given sized unit, it is the same as 10,000
other similar homes in the region that have the same sized units and are
comfortable, I'd trust the guy with 35 years experience to say, "yep, this
size is OK".

I don't care how well the calculations are done, the situation will change
anyway. You have three more kids that add body heat and more laundry and
the associated heat load. Cooking heat load. A big tree gets cut down. A
small tree grows up. The four teenagers you have now move out of the house
and it is just the two of you. You add a better storm door. You leave the
garage door open. All these things affect how well the AC works in YOUR
situation.

I told the story before. I used to quote tooling for our company. I'd do
the estimate in less than five minutes. The engineer in the machine shop
would do the calculations over a period of three days and a few hours of
actual calculating and getting quotes from suppliers. We'd be within $100
or less on a $10,000 tool, every time. He felt the need to do the math each
and every time. I started out looking at what he quoted for a similar item
and use his numbers over and over again.

If you feel comfortable with the guy, he is probably the best for you in
your situation.
--
Ed
http://pages.cthome.net/edhome/