909.1 General
Vented wall furnaces are installed in accordance with their listing and the manufacturer’s instructions. Oil-fired wall furnaces are tested in accordance with UL 730.
909.2 Location
Wall furnaces must be located so they do not create a fire hazard to walls, floors, combustible furnishings or doors. A furnace installed between a bathroom and an adjoining room must not circulate air from the bathroom to other parts of the building.
909.3 Door swing
A door may not swing within 12 inches of a furnace air inlet or outlet, measured at right angles to the opening. A doorstop or door closer cannot be used to create that clearance. The layout has to work on its own.
909.4 Ducts prohibited
Ducts cannot be attached to wall furnaces. Casing extension boots are prohibited unless they are listed as part of the appliance.
909.5 Manual shutoff valve
A manual shutoff valve is installed ahead of all controls.
909.6 Access
The furnace stays accessible for cleaning heating surfaces, removing burners, replacing sections, motors, controls and filters, adjustments, and lubricating serviceable parts. Panels, grilles and access doors required for normal servicing cannot be attached to the building construction.
Why it matters
Most wall-furnace problems are coordination problems: a nearby door blocks the inlet or outlet, casework or finishes cover the service panels, someone adds field ductwork, bathroom air is recirculated into adjoining spaces, or the appliance ends up trapped behind permanent construction.
Where to show it
As applicable: mechanical floor plans; equipment schedules with the listed model; architectural door swings; wall sections; gas or fuel piping plans with the shutoff; equipment details; and the manufacturer’s installation data.
Do
Verify the exact listed appliance.
Coordinate door swings before fixing the location.
Keep the service access clear and removable.
Show the manual shutoff valve.
Confirm any extension boot is part of the listing.
Do not
Attach ducts to the furnace.
Use a doorstop or closer to create the 12-inch clearance.
Trap removable service panels behind finishes.
Let bathroom air circulate into other areas.
Field tip
Overlay the furnace on the architectural door swings and the service-clearance envelope before permit. That one check can prevent relocation after finishes are installed. Access rules that apply to every appliance: IMC 306 equipment access. Next: IMC 910 floor furnace placement.
Code basis
2024 IMC 909 model-code education from the owner-provided Daily Code Talk. Review the complete ICC 2024 IMC Chapter 9. Gas-fired wall furnaces also follow the fuel-gas code. Confirm the locally adopted edition and amendments, the listing and the manufacturer’s instructions.