Who is doing the HVAC work?

They would have to do a Manual J to size the equipment to bid.

Who created the plans?
They should have enough info to do the calculation also.

The HVAC companies in my area don't use the Manual J to size a home. They simply say 500 sq ft for 1 ton of air conditioning.

I'm having spray foam insulation installed and triple glass windows. Our local companies also don't have knowledge about the spray foam insulation.

I live in South Louisiana in a small area. The company that will do the spray foam work will travel 70 miles to us. I'm trying to buy locally so when there is a problem - getting service won't be an issue.

I have found a company that will do the manual J for .28/sq ft. I'm considering sending them my plans Monday.

Robert,

You can try a program called HVAC-Calc that will allow you to the the Manual J yourself. Since you are doing spray foam and obviously trying to do things right, you'll easily save the cost of the program in savings on not getting an oversized system. I used it myself to do my own Manual J after I saw the one my installer's wholesaler did for my home. They did not take into account any of the things I did like ICFs, low-e double pane windows, and wetblown cellulose. They didn't even bother to get the plan orientation right. How many west facing windows you have can be a big deal when it comes to cooling load.

Be prepared to receive some resistance from your installers with what will undoubtably seem like a low number to then. Trust the math. It is also very important that they size the ducts adequately and do returns in all the bedrooms.

Many of the pros you'll see on boards like this pride themselves on doing things the right way. It's often very hard to find people like that in the real world.

Here is a link that might be useful: HVAC-Calc

Very important to have a Manual J done for a new home. The rules of thumb just aren't applicable anymore, and they never were quite frankly. The problems associated with oversized systems (higher bills, less humidity removal, shorter life, etc.) aren't worth the gamble to guess on sizing. I would be wary of having anyone install a system in my house who wants to use 500 sqft/ton--what other corners are they willing to cut?

Lemme second klabio's post--my story:

New 2700sf home with SIPs, double-pane windows, many facing south BUT under wide overhangs. HVAC sub put in 3.5 tons, after I told them HVAC-Calc estimated 2 tons (his vendor did Manual J without ever seeing the house). Long story short, we started getting mold in the basement due to high humidity. Had him rip out and replace with 2 tons...OK ever since...hot summers--no problems. You need to do this CORRECTLY.