Frequently Asked Questions

In most Canadian provinces, yes. CSA B149.1 requires that combustion air for gas appliances be controlled by an automatic, interlocked motorized damper — manual dampers are not permitted in combustion air ducts.

The standard install for a new gas furnace in Alberta, BC, Ontario, Saskatchewan, and Manitoba requires a HOM Series combustion-air damper wired with an ADP relay to interlock the damper with the furnace.

Requirements vary by province and appliance type. See our Code Compliance Guide for your region.

The HOM Series is a motorized combustion-air damper for gas and oil-fired appliances. It closes when the appliance is not firing and opens when combustion air is needed — preventing standby heat loss and meeting code requirements for interlocked combustion air.

The HAC Series is a universal inline air control damper for fresh-air ventilation, HRV/ERV intakes, make-up air, and zone control. It is not a combustion-air damper — it controls ventilation airflow across a wider range of applications.

Most installations in Alberta, BC, and Ontario require both: a HOM for the combustion air duct and a HAC for the HRV or ventilation intake.

For oil-fired equipment, use the HOM Series damper wired with an ADP relay to interlock with the burner control circuit. CSA B139 requires the damper to be automatic and interlocked so the burner cannot fire until the damper is fully open.

Oil-fired sizing uses approximately 1 in² per 5,000 BTU — confirm with your local inspector as requirements vary by jurisdiction. Atlantic Canada installations commonly use this configuration.

For most installations — yes, you need both. The ADP relay is what creates the interlock between the damper and the appliance. Without it, the furnace or boiler has no way of confirming the damper is open before firing.

The ADP simplifies wiring by eliminating the need for custom relay circuits. It connects directly into the furnace control board and is the recommended solution for most residential HOM installations.

The only exception is if you are wiring a custom interlock circuit directly — contact technical support if you are unsure.

Size is based on total BTU input of all appliances sharing the combustion air duct, using 1 sq. in. of duct area per 7,000 BTUH:

Sizing basis: 1.0 sq. in. of duct cross-section per 7,000 BTUH per Hoyme installation guidelines. For oil-fired appliances, many jurisdictions use 1 in² per 5,000 BTU. Always confirm with your local inspector before installation.

Yes. The HAC Series is commonly used on HRV and ERV fresh-air intake and exhaust ducts to control airflow and prevent heat loss when the unit is not running.

For HRV/ERV interlock wiring, the HAC damper can be connected to the HRV control signal so it opens and closes with the unit. Contact technical support for wiring guidance specific to your HRV model.

Power Open (PO) and Power Closed (PC) refer to the fail-safe position of HAC Series fresh-air and ventilation dampers — not the HOM combustion-air damper.

Power Open (PO) means the damper opens when 24Vac is applied and spring-closes when power is removed. The duct is sealed when the system is off. This is the standard configuration for most fresh-air intake and HRV/ERV applications.

Power Closed (PC) means the damper closes when powered and spring-opens when power is removed. Used in specific applications where the fail-safe position must be open rather than closed.

The HOM combustion-air damper is different. It is power-closed and gravity-open — power holds it closed when the appliance is not firing, and it drops open by gravity when the appliance calls for heat. This is not the same as PO or PC.

For HAC fresh-air intake and HRV/ERV applications: PO is correct for most installations. If you are unsure which applies to your application, contact technical support.

Yes. Hoyme HOM Series combustion-air dampers are CSA certified for use in combustion air ducts as required by Canadian building codes. CSA certification is required when a damper is installed inside a dwelling under CSA B149.1.

For certification documentation for a specific inspection, contact hoyme@hoyme.com or call 1-800-661-7382.

Wiring diagrams and installation guides for all Hoyme products are available in our Technical Library. Each guide includes step-by-step instructions, wiring schematics, and troubleshooting notes.

If you need help with a specific wiring scenario, email a photo of your setup to hoyme@hoyme.com or call 1-800-661-7382.

Most Hoyme HOM and HAC series dampers operate on 24V AC — the standard control voltage used in residential HVAC systems. This allows direct integration with furnace control boards and thermostat wiring without additional transformers in most installations.

120V AC models are also available for sites without a low-voltage control circuit (HAC-12 series). Always confirm voltage requirements for your specific model in the product installation guide before wiring.

The end switch is a built-in microswitch that signals when the damper blade has reached the fully open position. This signal is what the ADP relay uses to confirm to the furnace control board that it is safe to fire.

If the end switch is not making contact — due to misalignment, obstruction, or a wiring issue — the furnace will not fire even if the damper appears open. This is the most common cause of "damper open but furnace won't fire" issues.

The most common reasons a combustion-air damper installation fails inspection:

• Damper is not interlocked with the appliance — furnace can fire with damper closed
• Wrong damper size for total BTU load
• Manual damper used instead of automatic motorized damper
• Damper not CSA certified for combustion air use
• Damper installed in wrong location relative to appliance
• Wiring does not match the installation guide diagram

If your installation failed, call technical support at 1-800-661-7382 — we can usually diagnose the issue quickly over the phone.

This is almost always an end switch or ADP wiring issue. Check in this order:

• Confirm the end switch is making contact when the damper is fully open
• Check the ADP wiring matches the diagram — specifically the interlock terminals
• Confirm 24V is present at the damper terminals when the furnace calls for heat
• Check for a loose wire at the ADP terminal block
• Confirm the furnace control board is receiving the end switch signal

Send a photo of your wiring to hoyme@hoyme.com and our technician will respond same business day.

A humming damper that does not move usually indicates one of the following:

• The damper blade is physically obstructed — check for debris, ice, or duct obstruction
• The damper was installed in a section of duct that is too tight — confirm clearances
• The actuator motor is receiving power but the blade mechanism is seized

Do not leave a humming damper powered continuously — this can damage the motor. Call 1-800-661-7382 for diagnosis.

In most Canadian provinces, yes. CSA B149.1 and CSA B139 require combustion-air dampers to be automatic and interlocked. Manual dampers are not permitted in combustion air ducts.

For a full province-by-province breakdown see our Code Compliance Guide.

Yes — when installed correctly. Alberta requires an automatic motorized damper with mandatory interlock. The HOM Series with ADP relay satisfies Alberta requirements for most residential installs.

For 99% of Alberta homes: a 4" or 5" HOM with ADP is the correct combination. See the full Alberta code guide.

Yes. Hoyme dampers are compatible with IRC, IECC, and NFPA fuel code requirements and are used across cold-climate, mixed-climate, and warm U.S. states.

U.S. sizing requirements may differ slightly — always confirm with the local authority having jurisdiction (AHJ). See our U.S. code guide.

For most residential markets, a core stocking program of 8–12 SKUs covers the majority of contractor demand. The highest-volume SKUs are the 4" and 5" HOM dampers with ADP relay — these two combinations cover the majority of residential furnace installs in most Canadian provinces.

Hoyme provides branch-level stocking recommendations based on your region and market mix. Contact our order desk to discuss a stocking program tailored to your branch.

Hoyme products are designed for low return rates. Clear labeling, consistent wiring diagrams, and straightforward installation reduce contractor errors and call-backs — which directly reduces returns to the branch.

Most returns are wiring-related rather than product defects. Hoyme's technical support team is available to help contractors resolve wiring issues before they result in a return.

Hoyme maintains steady inventory on core SKUs to support wholesaler stocking programs. Lead times and minimum order quantities vary by product and order volume.

Contact our order desk for current availability, lead times, and wholesale pricing: hoyme@hoyme.com or 780-672-6553.

Yes. Hoyme provides counter display materials, product selection guides, and technical reference cards to help counter staff confidently recommend the right product.

Contact our sales team to request display materials for your branch: hoyme@hoyme.com.

Yes. Hoyme provides product training for counter staff and outside sales teams to help them confidently explain applications, recommend the right products, and answer common contractor questions.

Training covers product selection, sizing, code requirements by region, and wiring basics. Contact us at hoyme@hoyme.com to arrange training for your branch.

Hoyme supports distributor visibility through the website distributor locator, product literature that references stocking branches, and technical support that directs contractors to their nearest wholesaler.

When contractors contact Hoyme technical support, our team directs them to local stocking branches. We can also include your branch in our distributor locator once your account is set up.

Hoyme's technical support team is available to handle contractor wiring and installation questions directly — so your counter staff don't have to. If a contractor calls your branch with a technical question your team can't answer, direct them to:

Technical Support: 1-800-661-7382
Email: hoyme@hoyme.com

We handle the technical questions so your team can focus on the sale.

Hoyme is actively expanding its distribution network across Canada and the United States. We work with HVAC wholesalers who serve residential and light-commercial markets and want a focused, code-driven product line with strong contractor demand.

Visit our Become a Partner page to learn more or apply directly.

Yes. Hoyme works with both single-branch and multi-location wholesalers. For multi-branch networks, we can discuss regional stocking programs, consolidated ordering, and branch-specific stocking recommendations based on local market demand.

Contact us at hoyme@hoyme.com to discuss a regional program.

Onboarding typically includes account setup, an initial stocking recommendation for your market, product and application training for counter staff, and access to Hoyme's technical support line for contractor inquiries.

We aim to make onboarding straightforward — most new branches are set up and stocked within a few weeks of account approval. Contact hoyme@hoyme.com to get started.