HVAC replacement cost: full system prices

A full replacement usually means a new outdoor AC or heat pump, a new furnace or air handler, a matched indoor coil, and the work to connect them to your existing ducts. The ranges below are national figures from one publisher. They are a starting point for judging a quote, and your price can sit outside them.

If you only need one half of the system, see the separate guides to AC replacement cost and furnace replacement cost.

• Size. Bigger homes need more tons of cooling and more BTU of heating. The right size comes from a load calculation on your house. A contractor who sizes by square footage alone, or simply matches the old unit, is guessing.
• Efficiency. Higher SEER2 and AFUE ratings cost more up front and less to run. The payback depends on your climate and energy rates.
• Ductwork. Reusing sound ducts keeps the price down. This Old House notes that new or major ductwork can add several thousand dollars.
• Access. Attic and crawlspace equipment takes longer to swap than a unit in a garage or basement.
• Fuel and electrical changes. Switching from gas to a heat pump, or the other way, can mean new wiring, a new gas line or a new flue.
• Permits. This Old House describes permit fees as typically a few hundred dollars, varying by location.

Ask every contractor for the same level of detail so you can compare line by line.

• The exact model numbers and capacity of the equipment or part being installed.
• Labor, materials and refrigerant listed as separate lines.
• Permit and inspection fees, and who pulls the permit.
• Removal and disposal of the old equipment.
• The parts warranty and the labor warranty, each with its length in writing.

Also ask whether the quote includes a load calculation, a new thermostat, a new refrigerant line set, and any duct sealing or repairs. Two quotes with the same total can cover very different work.

The AC and the furnace share a blower and an indoor coil, so replacing them together avoids paying for overlapping labor twice and keeps the parts matched. It makes the most sense when both are old. This Old House gives typical lifespans of 10–15 years for air conditioners and heat pumps and 15–20 years or more for furnaces with proper care.

If the furnace is much newer than the AC, replacing only the cooling side is reasonable, as long as the new outdoor unit is compatible with the existing furnace blower. Ask the contractor to confirm the match in writing.

A full system is a large bill to face at short notice.