Does the HOM require an ADP relay adaptor?

On a standard 24Vac furnace system the HOM wires directly to the W terminal on the furnace control board — no ADP is required. The ADP relay adaptor is only needed for non-24Vac systems such as millivolt safety circuits or 110Vac boilers and tankless water heaters.

Where does the HOM damper mount on the duct?

The HOM mounts vertically on the combustion air duct at the appliance end — within one foot above burner level. It does not mount horizontally or at the wall. Vertical mounting at the appliance end is required for correct operation and code compliance.

What is the difference between the SF1 and SF2 variants?

The SF1 variant is for installations serving one appliance. The SF2 variant is for installations serving two appliances from the same combustion air duct. Both include a relay and end switch as standard.

What happens if the HOM damper fails to open?

When the HOM is wired with an end switch and ADP relay adaptor, the appliance cannot fire until the end switch confirms the blade has physically reached its open position. If the damper fails to open due to a frozen blade, motor fault, or wiring problem, the appliance stays off and the fault is detectable.

Is the HOM CSA certified?

Yes. The HOM combustion air damper is CSA certified for use on gas and oil-fired appliances in Canada and the United States.

HOM Combustion Air Damper – CSA Certified, 24Vac, 4

Product image is representative only. Actual product may differ in appearance depending on size, configuration, and options selected at order.

CSA-certified motorized combustion air damper for furnaces, boilers, fireplaces, and water heaters. The appliance cannot fire until the damper proves open — closing the combustion air intake when the appliance is off and interlocking it with the appliance safety circuit on demand. 24 Vac, 4"–9", Power Close / Spring Open.

✓ Power Close / Spring Open — motor holds the damper closed when the appliance is off; spring opens it the moment power is removed when the appliance fires, keeping the combustion air path clear

✓ CSA certified — complete assembly — damper body, drive, and control hardware together; covers Canadian and US installations

✓ Built-in end switch — confirms blade has physically reached open position; required for ADP relay adaptor combustion air interlock so the appliance cannot fire until the damper proves open

✓ Test/Run switch — allows manual override to hold the damper open for summer months or appliance troubleshooting without powering the motor continuously

✓ Adjustable extension sleeve — covers wall thicknesses 7½"–14" without custom fabrication; flashing included

✓ Not suitable for dryer ventilation — lint accumulation in the motor assembly causes premature failure; use the BDH Back Draft Hood for dryer exhaust

SF1

Single-furnace — one appliance

Controls and interlocks one furnace, boiler, or appliance. Standard configuration for most residential installations.

SF2

Dual-furnace — two appliances

One damper interlocks with two appliances. Either appliance calling for heat opens the damper; neither can fire until it proves open.

SF1 vs. SF2 — confirm before ordering. SF1 is for installations with one appliance sharing the combustion air duct. SF2 is for installations where two appliances share the same combustion air duct and either may call for heat independently. For commercial applications with appliances rated over 400,000 BTU, slave dampers can be added to the SF1 or SF2 — contact the factory.

Interlock

Appliance cannot fire until damper proves open

Sizes

4"–9"

Voltage

24 Vac

Action

Power Close / Spring Open

Wall Thickness

7½"–14" adjustable

Certification

CSA — complete assembly

Need an ADP relay adaptor? For combustion air interlock — appliance cannot fire until the HOM end switch confirms the damper is open — pair the HOM with the correct ADP: ADP-0MV2-S5A (millivolt appliances), ADP-0240-05A (24 Vac furnace), or ADP-1102-S5A (120 Vac boiler/tankless).

2-year electrical · 10-year mechanical warranty

Made in Canada · 40+ years field-proven in Canadian climates

HOM Motorized Combustion Air Damper — CSA Certified, 24 Vac, 4"–9", Spring Return

Description

HOM Motorized Combustion Air Damper — CSA Certified, 24 Vac, 4"–9", Spring Return