Description
Product image is representative only. Actual product may differ in appearance depending on size, configuration, and options selected at order.
Back draft hood for exhaust duct terminations at the building exterior — dryer, bathroom fan, kitchen exhaust, HRV/ERV exhaust port, or any exhaust duct at the wall. Opens when the fan runs, closes when it stops. No wiring. No power. No maintenance. Spring closed models mount any orientation. Gravity closed models for horizontal discharge. Sizes 4"–12".
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Outlet only — closes when the fan stops — eliminates the open path for outdoor air, cold, and pests that exists at every exhaust termination without a closing damper
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Spring closed — mounts any orientation — vertical, horizontal, or angled; spring provides consistent closing force regardless of gravity; the correct specification for dryer exhaust
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Gravity closed — quieter, aesthetic priority — lighter operation on horizontal discharge; defaults to painted white for white-siding installations; not suitable for vertical or angled discharge
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End switch available on spring closed models at 4", 5", and 6" — proves hood-open position for fan proving circuits, ventilation interlock sequences, or dryer proving requirements; not available on gravity closed or on spring closed models larger than 6"
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Both finishes available on both styles — spring closed defaults to regular metal, gravity closed defaults to painted white; specify alternate finish at order if needed
Outlet only — not for fresh air intake applications. On an inlet, outdoor air pressure pushes the BDH open and holds it open with no control. For passive fresh air intake termination use the OOH All Weather Hood. For powered open/close at the wall use the MOH Motorized All-Weather Hood.
Spring Closed — specify when…
✓Dryer exhaust — always spring closed
✓Vertical or angled discharge — spring closes reliably in any orientation
✓Fan proving or interlock circuit required — end switch available at 4", 5", 6"
✓Any orientation uncertainty — spring is the safer default
Gravity Closed — specify when…
→Confirmed horizontal discharge only
→Quieter operation is preferred — lighter mechanical action
→White siding installation — painted white is the default finish
→No fan proving or interlock circuit required
| Size | Spring Closed | Spring Closed + End Switch | Gravity Closed |
|---|---|---|---|
| 4" | BDH-0400-000 | BDH-0400-S00 | BDH-0400-000-G |
| 5" | BDH-0500-000 | BDH-0500-S00 | BDH-0500-000-G |
| 6" | BDH-0600-000 | BDH-0600-S00 | BDH-0600-000-G |
| 7" | BDH-0700-000 | — | BDH-0700-000-G |
| 8" | BDH-0800-000 | — | BDH-0800-000-G |
| 9" | BDH-0900-000 | — | BDH-0900-000-G |
| 10" | BDH-1000-000 | — | BDH-1000-000-G |
| 12" | BDH-1200-000 | — | BDH-1200-000-G |
11" is not available in this series. End switch (S00) is only listed in the standard price book at 4", 5", and 6" — confirm availability at larger sizes with your wholesaler before ordering.
Application
Outlet only — exhaust termination
Sizes
4"–12" (no 11")
Styles
Spring closed / Gravity closed
End Switch
Spring closed, 4"–6" only
Not Suitable For
Inlet applications — use OOH or MOH
Gravity Closed Mounting
Horizontal discharge only
Operation
No power, no wiring required
Warranty
10-year mechanical
Need to confirm actual airflow in the duct run — not just hood position? The end switch proves the hood has opened, not that a specific flow rate is achieved. For precise airflow confirmation use the PFS Positive Flow Switch inline in the duct run. For an inline back draft damper (not at-wall termination) see the BDD Back Draft Damper.
10-year mechanical warranty
Made in Canada · No motor, no wiring, nothing to fail electrically