Hi! I am in the process of receiving quotes on replacing one of my split systems. For this particular system, I mentioned that one of the smaller bedrooms is stuffy when the door is closed at night. After asking some questions, each of the three vendors proposed three different solutions:

Vendor 1) Since this bedroom is the closest to the air handler, he'll install new duct work to jump directly from the supply to the room bypassing the distribution box.

Vendor 2) He will install manual dampers in the duct work (in the attic) to balance the flow going to each of the locations handled by the distribution box. Once the dampers are set, they will be left alone.

Vendor 3) What Vendor 2) is proposing is okay for commercial properties here in Florida, but now legal for residential properties. Is that true? I believe he said the dampers have to be motorized for a residential installation. His proposal is to put in bigger ducts for the supply in the return for the room. The grills already appear to be sized to handle the larger ducts.

Is Vendor 3)'s comment about the legality true? Any other comments about the proposals?

BTW, Vendor 2) will be doing a load analysis after I sign on the dotted line. Vendor 3) is working on a Manual J as part of the sales quote. Is it possible to do a load analysis that is not a full Manual J but that still meets our permitting requirements here in Florida?

Location is Orlando Florida
Air handler is Carrier Infinity 58CVA110, which includes a gas furnace

Many thanks in advance!