Description
Product image is representative only. Actual product may differ in appearance depending on size, configuration, and options selected at order.
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 patented 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 patented Hoyme spring motor drive — stall-protected, holds against elevated duct static pressure on pressurized zone systems without tripping
✓ CSA certified — complete assembly — covers Canadian and US installations
✓ 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. A field conversion procedure exists — it requires removing the motor, reversing the spring plate, and remounting the drive — but this is not practical once the unit is installed in a duct run. 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
CSA — complete assembly
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