Furnace replacement: include the venting plan in the quote

Questions covered in this guide

Ask about the complete route

Before comparing furnace proposals, ask the installer to show where the proposed equipment takes combustion air and where it sends exhaust. DOE's building-science guidance describes direct-vent equipment as bringing combustion air from outdoors and carrying exhaust outdoors through sealed venting. The cabinet model alone does not answer how that arrangement will be installed at your house.

Have the contractor mark the proposed work

Request a simple sketch with the furnace location, planned routes and exterior terminations. Ask which existing components would remain and which would be removed or replaced. Include any other appliance sharing an existing vent in the conversation, and ask the contractor to explain how it will be addressed. Let the professional determine the materials, sizing and clearances for the specified equipment and local requirements; a national planning article cannot supply that design.

Define who restores the affected areas

Put penetrations, sealing, finish repairs and disposal on the proposal sheet. Ask whether the quoted total includes those tasks and who performs them. If the planned route cannot be confirmed until a visit, mark it unresolved rather than assuming a straight equipment swap. Request an explanation of the planned startup and safety checks. DOE describes backdrafting as combustion products being drawn indoors; that is a reason to obtain a professional installation plan, not attempt a homeowner vent modification.

Close the scope before comparing prices

Compare bids using the same documented route and restoration responsibilities. Ask for a revision if the selected furnace changes the proposed work. Keep the final sketch and completion records with the equipment information. The HVAC calculator provides a budget starting point and accepts supplied prices; it does not inspect a chimney, design venting or establish that an installation is safe.

Putting it into practice

A route sketch and restoration checklist turn venting into an explicit scope item. The comparison also asks how retained appliances are addressed without prescribing a vent design or homeowner installation procedure.

Sources and supported claims

DOE describes direct-vent combustion equipment as using outdoor combustion air and sealed exhaust venting to outdoors.
Source ↗ · national · Checked 2026-10-12

DOE describes backdrafting as combustion products being drawn back inside a house.
Source ↗ · national · Checked 2026-10-12