How to quote an HVAC installation

Every figure in an HVAC quote descends from one number, and that number is not the floor area. Equipment is sized from a load calculation, and a system sized from square footage instead is the most common and most expensive mistake in the trade — oversized units short-cycle, never dehumidify, and fail early.

Size the system before you price anything

  1. Run a room-by-room load calculation

    Insulation, window area and orientation, air leakage, ceiling height and local design temperatures all feed it. Two identical floor plans on the same street can need different capacity.

  2. Check the existing ductwork against the load

    Duct sized for the old system may not carry the airflow the new one needs. Static pressure is what decides whether the ducts are part of the job, and it is measured rather than assumed.

  3. Confirm the electrical service can take it

    Breaker capacity, wire size and disconnect location are all part of the installation, and finding a full panel on the day is a delay and an electrician nobody has quoted.

  4. Price the line set, drainage and the pad or platform

    The equipment is the headline and these are the installation. Refrigerant line runs, condensate routing and where the outdoor unit actually stands are all decided at the survey.

Ductwork is its own scope

Modifying, sealing or replacing duct is a materially different job from swapping equipment, and it is where a quote most often diverges from a competitor's. State exactly what the price includes — a plenum and transitions only, sealing existing trunks, or new runs to named rooms — because a client comparing two quotes cannot otherwise tell that one of them is doing twice the work.

What has to be excluded

What moves an HVAC number up

  • Permits and third-party inspection, which many jurisdictions require for a change of equipment
  • Efficiency tier and refrigerant type, which change both the equipment and what it needs around it
  • Zoning, dampers and controls, which are a system design rather than an accessory
  • Attic or crawl-space work, where access rations how much can be done in a day
  • Removal and disposal of the old equipment, including recovering the refrigerant in it

Hold the price for thirty days

Valid for 30 days, and it is the distributor's window rather than yours: equipment pricing is held for roughly that long, and beyond it the same model number can cost something different. Say that the figure covers the equipment named on the quote, so that a substitution is discussed rather than assumed when a model goes out of stock.

Start from the HVAC quote template

Common questions

Can equipment be sized from square footage?
No. A load calculation accounts for insulation, window area and orientation, air leakage and design temperatures, and identical floor plans can need different capacity. Sizing from area routinely produces oversized systems that short-cycle and never dehumidify.
Should ductwork be in the same quote?
It should be in the same quote and on its own lines, saying exactly what is included. It is the largest difference between two quotes for the same equipment, and a client cannot see it unless it is written down.
Why does the electrical service matter?
Because the installation includes the breaker, the wire and the disconnect, and a panel with no capacity turns the job into an electrical upgrade that was never priced. It is checked at the survey for that reason.

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