Description
CSA-certified motorized inline zone damper for hot air supply duct control where full shutoff causes heat buildup, high-limit trips, or thermal stress. A 10% bypass is machined directly into the blade at the factory: permanent, consistent, always present. Same stall-protected Hoyme 24 Vac spring return drive as the standard HAC. Sizes 2"–9".
Not for fresh air, make-up air, or ventilation applications. The 10% bypass is permanent and cannot be disabled. On a fresh air or outdoor air duct, outdoor air infiltrates the building continuously through the bypass whenever the damper is commanded closed, every hour, every day, every season. If a HAC-H has been installed on a fresh air application in error, it must be replaced with a standard HAC.
✓ 10% bypass machined into the blade at the factory: not a field modification, not an adjustable insert, not removable; consistent on every unit
✓ Prevents high-limit trips on single-speed furnaces: maintains minimum airflow through closed zones, relieving static pressure and keeping heat exchanger airflow above the trip threshold
✓ Same stall-protected Hoyme spring motor drive: holds against elevated duct static pressure on pressurized zone systems without tripping
✓ Canada/USA CSA certified
✓ PO or PC action, end switch and relay available: all factory-installed; relay not available on 2" and 3"
✓ Replacement parts stocked: motor kits, microswitch kits, spring return kits at your wholesaler; drive services in place
Confirm PO vs. PC before ordering. The action is set at the factory. If it needs to change, it can be converted in the field by removing the motor, reversing the spring plate, and remounting the drive, following the Hoyme conversion procedure. For most hot air zone control applications PO is correct: the zone opens when called and spring-closes when the call ends. PC is used only when the zone must fail open on power loss; confirm with the system designer before specifying PC on a zone damper.
Use HAC-H when…
✓Hot air supply duct zone control: single-speed furnace
✓Closing supply zones causes high-limit trips or heat buildup
✓Minimum airflow through all zones required regardless of call status
✓Variable speed furnace: bypass may still be preferred; confirm with system designer
✓120 Vac site: see HAC-12H
Use standard HAC when…
→Fresh air intake, make-up air, or ventilation: full shutoff required
→Return air zone control: bypass not required on return side
→HRV / ERV duct control: bypass allows reverse infiltration
Bypass
10%: factory machined, permanent
Sizes
2"–9"
Voltage
24 Vac
Action
PO or PC
Certification
Canada/USA CSA
Not Suitable For
Fresh air, make-up air, ventilation
120 Vac site? The HAC-12H combines the 120 Vac built-in transformer with the same 10% bypass blade. Use HAC-12H when only 120 Vac is available at the damper location and hot air zone control with bypass is required.
2-year electrical · 10-year mechanical warranty
Made in Canada · CSA certified for Canadian and US installations
Product image is representative only. Actual product may differ in appearance depending on size, configuration, and options selected at order.
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