Bump.

We just installed a custom hood with Broan PIK 45 and EB 15 external 1500 cfm blower. There clearly is still a bit of a draft. I'm going to talk to our contractor / HVAC guys tomorrow about installing this back-draft gizmo.

Any input or comments appreciated.

Will post updates.

attofarad:

My hood has a damper just above it supplemental to the one on the output side of the roof fan. I don't think the hood damper adds significant noise, but a comparison test would be extremely inconvenient.

In any case, differential pressures due to wind gusts will cause some damper opening, so a pair of dampers provides additional resistance to air infiltration down the duct.

kas

Thanks Kas, I will just add it right to the hood port.

Gary