CSA Certified · 24 Vac · 2"–9" · Spring Return

The HAC
Universal Inline
Air Control Damper

Fresh air intake · Make-up air · HRV/ERV duct control · Zone control. Hoyme's core motorized inline damper, built on the stall-protected Hoyme 24 Vac spring return drive. Canada/USA CSA certified, 2" to 9".

Need 120 Vac? See HAC-12 · Need a flue damper? See HAC-F · Need combustion air? See HOM

Canada/USA CSA certified
Stall-protected Hoyme spring drive
2-yr electrical · 10-yr mechanical warranty
Serviceable in place: field-replaceable motor, switch and spring kits
Hoyme HAC Motorized Inline Air Damper, relay and end switch variant
Hoyme HAC Motorized Inline Air Damper, standard variant

Contractor? Order through your HVAC wholesaler for your account pricing. Find a wholesaler

No wholesaler account? Buy direct online at list price. Ships across Canada and the US. Buy online · How to buy

Not sure it's the right part? Call 1-800-661-7382 for free technical support.

WHERE IT'S USED

One Damper. Four Common Applications.

The HAC is Hoyme's core motorized inline damper. It handles fresh air intake, make-up air, HRV/ERV duct control and zone control, all in one Canada/USA CSA certified damper built around the stall-protected Hoyme 24 Vac spring return drive.

Fresh Air Intake

Installs inline in the fresh air duct run. Opens when ventilation is called and spring-closes between cycles, sealing the duct against cold air infiltration when the system is off.

TYPICAL SPEC

HAC + ADP-0241-05A

Power Open (PO) · No end switch (OPO)

HRV / ERV Control

Controls the fresh air supply duct on HRV and ERV systems. Opens on a ventilation call and closes when the cycle ends, preventing outdoor air from infiltrating through the HRV core when the unit is off.

TYPICAL SPEC

HAC wired to HRV/ERV output

Power Open (PO) · Standard or end switch

Make-Up Air

Interlocked with exhaust fans to supply replacement air when the exhaust runs. Prevents negative building pressure on range hoods, commercial exhaust and tight residential construction.

TYPICAL SPEC

HAC interlocked with exhaust fan

Power Open (PO) · End switch as required

Zone Damper Control

2-position open/close zone control on heating and cooling systems. Use the standard HAC on return air zones or variable-speed systems. For hot air supply zones on single-speed furnaces, specify the HAC-H with the 10% bypass blade.

TYPICAL SPEC

HAC (return/variable speed) · HAC-H (hot supply)

Power Open or Power Close · per system design

HOW IT WORKS: FRESH AIR + FURNACE FAN SEQUENCING

On a fresh air system interlocked with a furnace fan, the HAC and the furnace fan run together on a ventilation call. How well the outdoor air is tempered depends on where the fresh air duct joins the return and how much outdoor air is drawn, so plan both at rough-in.

1

Ventilation call

ADP-0241-05A receives the signal from the 24 Vac ventilation switch or controller

2

HAC opens

One relay opens the damper and turns on the furnace fan at the same time

3

Air is distributed

The furnace fan moves the outdoor air through the house with the return air

Interlocking the HAC with the furnace fan? Use an ADP.

The ADP-0241-05A (24 Vac switch) or ADP-1101-05A (120 Vac exhaust fan switch) opens the HAC and starts the furnace fan together. No field relay design, and colour wiring diagrams are included in every box.

View ADP Relay Adaptors →

CONFIGURATION GUIDE

Order the Right HAC the First Time

Three decisions determine your part number: size, action and options. All options are factory-installed, so confirm them before ordering. The action can be converted in the field using the Hoyme conversion procedure, but getting it right at order saves a service call.

1

Select Size: match to your round duct diameter

Available in 2", 3", 4", 5", 6", 7", 8" and 9". Match the HAC to the duct diameter exactly: undersizing or oversizing affects seal quality. Do not size to the appliance inlet collar.

2"

No relay option

3"

No relay option

4"

Full options

5"

Most common

6"

Most common

7"

Full options

8"

Full options

9"

Full options

Need 10" or larger? See HAC-50 / HAC-51 (quarter-turn actuator, 6"–14") or the HAC Belimo series (up to 20").

2

Select Action: confirm before ordering

This is the most common ordering error on motorized dampers. PO and PC are not interchangeable.

PO: Power Open

STANDARD

Opens when 24 Vac is applied. Spring-closes on power loss, so the duct seals between ventilation cycles.

✓ Fresh air intake, make-up air, HRV/ERV: correct for most installs

PC: Power Close

Closes when 24 Vac is applied. Spring-opens on power loss, so the duct stays open if power is lost.

✓ Exhaust control or applications requiring fail-open on power loss
3

Select Options: factory-installed, specify at order

The end switch and relay are independent options. Either, both or neither can be included, depending on the application.

End Switch (S prefix in part number)

Confirms the blade has physically reached its open or closed position. Required whenever a controller or a proving ADP adaptor (TPX models, gas dryer RADP models) needs position feedback before allowing another device to operate.

INCLUDE WHEN:

→ Using a proving ADP (TPX models) or gas dryer RADP
→ Controller requires position confirmation before next step

Relay (11 motor code)

Switched output that activates when the damper opens. Used when the damper opening must directly energize a furnace fan, exhaust fan or secondary device without an ADP relay adaptor in the circuit. Available on 4" to 9" sizes.

INCLUDE WHEN:

→ The damper must start a fan or other device directly
→ No ADP relay adaptor is being used in the circuit

SHOP HAC DAMPERS

Find Your HAC

The standard HAC covers most fresh air, make-up air and HRV/ERV installs. Use the variant cards below if your job has a specific requirement.

Hoyme HAC Motorized Inline Air Damper
Core Model

HAC Universal Inline Air Control Damper

CSA certified · 24 Vac · 2"–9" · Spring return · PO or PC · End switch & relay options · Fresh air intake, make-up air, HRV/ERV, zone control

Shop HAC →

VARIANTS: WHEN YOUR JOB HAS A SPECIFIC REQUIREMENT

ADP-0241-05A Fresh Air Relay Adaptor

COMMONLY ORDERED WITH HAC

ADP-0241-05A: Fresh Air + Furnace Fan Relay

Pre-engineered relay adaptor that opens the HAC and turns on the furnace fan at the same time. Use with an HAC without end switch (OPO or OPC). Colour wiring diagrams included.

View ADP Series →

Not sure which variant is right for your job?

Call technical support with your appliance type, duct size, control sequence and location, and we'll confirm before you order.

Call 1-800-661-7382

TECHNICAL DOCUMENTS

Installation & Wiring Resources

Instructions, wiring diagrams and spec sheets for a clean install and a straightforward inspection.

INSTALLATION & WIRING

HAC Installation & Wiring Instructions
+

Complete installation instructions covering mounting, duct connection, wiring options and commissioning for the HAC inline damper in all configurations: 24 Vac, PO/PC, with and without end switch and relay.

Download PDF
HAC-F Installation Instructions
+

Installation instructions for the HAC-F motorized flue damper: fail-safe orientation, wiring diagrams for gas and oil appliances, auxiliary transformer connection and appliance interlock procedure.

Download PDF
HAC-F Troubleshooting Procedure
+

Step-by-step field diagnostic procedure for three conditions: damper does not open, damper does not close after the firing cycle, and damper opens but the appliance does not fire.

Download PDF
Power Close ↔ Power Open Change Guide
+

Field guide for converting an HAC damper between Power Close and Power Open action: spring plate removal, remounting procedure and motor repositioning, with diagrams.

Confirm the required action with the system designer or Hoyme technical support before converting a damper in the field.

Download PDF
Colour Wiring Diagrams: HAC Configurations
+

80+ colour wiring diagrams cover HAC installation configurations: fresh air intake, ventilation fan interlock, furnace fan sequencing, two-furnace systems, gas dryer replacement air, timer adaptor and end switch proving. The most common diagrams are below; the full library is in the Technical Library.

View All 80+ Wiring Diagrams →

PRODUCT DOCUMENTS & SPEC SHEETS

HAC Product Information Sheet
+

General information sheet for the HAC Universal Inline Air Control Damper: product family overview, motor options, nomenclature and configuration reference.

Download PDF
HAC-F General Information Sheet
+

Dimensional drawing and specification overview for the HAC-F motorized flue damper: CSA certified, 24 Vac, 4"–9", with part number identification.

Download PDF
Hoyme Product Comparison Chart
+

Hoyme vs. Honeywell side-by-side comparison: warranty, construction, cycle life, country of origin and available product types. Made in Canada. 500,000+ cycle rating.

Download PDF

Need a document that's not listed?

ADP wiring diagrams are included in every ADP box. The complete library of 80+ colour wiring diagrams is in the Technical Library. For product-specific installation guides, service bulletins or other technical documents, contact technical support.

Need help with a wiring question on the job?

Technical support handles contractor wiring and application questions directly, so your counter staff don't have to.

COMMON QUESTIONS

HAC Damper FAQs

The questions contractors and counter staff ask most often, answered directly.

What's the difference between PO and PC, and which one do I need? +

PO (Power Open): the damper opens when 24 Vac is applied and spring-closes when power is removed. PC (Power Close): the damper closes when powered and spring-opens on power loss.

For fresh air intake, make-up air and HRV/ERV applications, PO is correct for most installations. You want the duct sealed when the ventilation system is not calling, which is the spring-closed (power off) position. PO delivers that.

PC is specified when the system design requires the duct to stay open if power is lost. That's uncommon on fresh air intakes but appropriate on some exhaust and pressure control applications.

⚠ Confirm PO or PC before ordering. This is the most common ordering error on motorized dampers.

How do I choose the correct HAC model and size? +

Three decisions determine your part number:

1

Size: match to your round duct diameter exactly

Available 2"–9". Do not size to the appliance inlet collar. Undersizing or oversizing affects seal quality.

2

Action: PO for fresh air (standard) · PC for fail-open applications

Confirm at order. The action can be converted in the field with the Hoyme conversion procedure, but ordering it right avoids the extra work. See the question above if unsure.

3

Options: end switch and/or relay as the application demands

End switch required for proving ADP sequences (TPX models). Relay for direct fan triggering, not available on 2" and 3" sizes.

Then confirm whether the standard HAC is right or whether a variant applies. See the configuration guide above, or call technical support with your appliance type, duct size, control sequence and location.

Do I need the end switch? When do I need the relay? +

They do different things, and both can be ordered on the same unit.

End Switch (S prefix)

Confirms the blade has physically reached its open or closed position, not just that the motor received power. Required whenever a controller or a proving ADP adaptor (TPX models, gas dryer RADP models) needs position confirmation before allowing another device to operate.

Include when using a proving ADP (TPX models) or a gas dryer RADP.

Relay (11 motor code)

Switched output that activates when the damper opens. Used when the damper opening must directly energize a furnace fan, exhaust fan or secondary device without an ADP relay adaptor in the circuit.

Not available on 2" and 3" sizes.

If you're unsure which option your system needs, call technical support with the appliance type and control sequence, and we'll confirm before you order.

Can HAC dampers be used with HRVs or ERVs? +

Yes. HRV and ERV applications are one of the most common uses for the HAC. The HAC installs on the fresh air supply duct and is wired to the HRV or ERV ventilation output. It opens when the unit calls for a ventilation cycle and closes when the cycle ends.

This matters because a passive installation leaves the fresh air duct open through the HRV core when the unit is off, which is a real infiltration path. The HAC closes that path between cycles.

HRVs and ERVs manage ventilation air quality; the HAC manages the duct. They work together, not instead of each other. For fresh air installations also interlocked with the furnace fan, pair with the ADP-0241-05A, which opens the HAC and starts the furnace fan together.

Do I need an ADP relay adaptor, or can I wire the HAC directly? +

If your thermostat or controller outputs a direct 24 Vac signal to open the damper when ventilation is called, you can wire the HAC directly. No adaptor is needed.

If the damper has to operate with the furnace fan, use the ADP-0241-05A (24 Vac ventilation switch) or the ADP-1101-05A (120 Vac exhaust fan switch). Both open the damper and start the fan together, with no end switch needed.

Where an exhaust fan must not run until the damper proves open, use a proving adaptor (ADP-1102-TPX or ADP-1103-TPX) with an end switch HAC (SPO or SPC). See the ADP series for the full model lineup, including combustion air, gas dryer and two-zone applications.

What's the difference between the HAC and the HOM? +

HAC: Fresh Air & Ventilation

Fresh air intake, make-up air, HRV/ERV duct control and zone control. Installs in a conditioned or interior duct run. Used where the application is ventilation control, not combustion air supply.

HOM: Combustion Air

CSA certified motorized damper specifically for combustion air intake on fuel-burning appliances: furnaces, boilers, fireplaces and water heaters. Must be interlocked so the appliance cannot fire until the damper proves open.

Many installs use both: an HAC on the fresh air ventilation duct and a HOM on the combustion air duct. They serve different code requirements. If you're controlling combustion air on a gas or oil appliance, you need the HOM, not the HAC.

What if the damper doesn't open? +

Start with the most common causes before assuming a product fault:

→ No 24 Vac at the damper: check that the ADP relay adaptor or controller is outputting voltage to the damper
→ End switch not included: proving ADP adaptors (TPX models) need the HAC ordered with the end switch (S prefix)
→ Wrong ADP model for the system voltage: confirm the ADP model matches the appliance type and voltage
→ Blade frozen or held against static pressure: the Hoyme stall-protected drive holds under load; if the blade is frozen, the motor will hold without tripping

Replacement motor kits, microswitch kits and spring return kits are available through Hoyme wholesalers, so the damper can be serviced in place. If the issue isn't resolved, call technical support at 1-800-661-7382.

Is the HAC suitable for retrofits? +

Yes. The HAC installs inline in the round duct run at any accessible point. It does not require access to the appliance or exterior wall. The mounting collar is included; no separate collar is required for standard duct connections.

For retrofits where the damper sits in an unconditioned space, near the exterior wall or in a crawlspace, consider the HAC-L with its factory-insulated body to prevent condensation at the damper.

The main planning consideration on retrofits is 24 Vac control wiring: plan the wire run from the controller or ADP location to the damper. If only 120 Vac is available at the damper location, see the HAC-12 with built-in transformer.

Who do I call if I'm unsure? +

Call Hoyme technical support directly. Have your appliance type, duct size, location (province or state) and control sequence ready, and we'll confirm the right product and part number before you order.

READY TO ORDER

The Right HAC, the First Time.

Shop the HAC series directly, or call technical support with your duct size, appliance type and location, and we'll confirm the right model and configuration before you order.

✓ Canada/USA CSA certified
✓ Stocked at HVAC wholesalers across Canada
✓ 2-yr electrical · 10-yr mechanical warranty
✓ Field-replaceable parts: serviceable in place
✓ Made in Camrose, Alberta since 1984