Design before you bid: an HVAC guide for home builders.

On most projects, HVAC is still priced backwards. The builder asks for bids, contractors size the system by rule of thumb to get a number out, and the real design, if it happens at all, comes after the job is awarded.

Put the design in the plan set

Architectural and structural drawings define the scope before anyone bids. A Manual J, S and D should do the same for the mechanical system. With the design in hand, every HVAC contractor prices the same equipment and the same duct layout, and you can finally compare bids on equal terms.

The three parts, in order

• Manual J calculates the heating and cooling load of every room.
• Manual S selects equipment that meets that load.
• Manual D sizes the ducts to deliver the right air to each room.

Skip any one of them and that step falls back to a guess.

Check the quotes you already have

Divide the home’s conditioned square footage by the quoted tonnage. Quotes in the 400 to 600 square feet per ton range deserve a second look on a new, code-built home. One of our contractor clients watched a competitor bid 25 tons of cooling on a project where the load calculation called for about 9.

What oversizing costs you after closing

Oversized systems short-cycle, control humidity poorly and wear out early. The comfort complaints arrive after closing, as warranty calls to your HVAC trade and as reviews about your homes. A right-sized design lowers equipment cost on the front end and callbacks on the back end.

A better story to sell

You already pay for good insulation, windows and air sealing. A system sized to match is what lets buyers actually feel those upgrades. A documented design is something your sales team can point to.

Built for volume

We work from your plan library. Each plan is designed once, orientation changes are documented, and repeat starts move fast. Custom homes get the full room-by-room treatment.