odd size duct-board

[vaguy]

I need to install an ND damper into a duct-board that measures 9x12 (inside)
I see 3 options
1 - use a 8x12 and live with the gap (or plug it)
2 - use a 10x12 and notch out 1/2" of the 1" duct-board top and bottom
3 - custom order (if that is possible) a 9x12 unit.

Plugging the gap in choice 1 would for sure reduce the overall CFM. I think the duct is undersized to begin with, so don't want to decrease it any more than necessary.

Any and all advice is welcomed.

[Erik W.]

Your only option would be to use a 8x12 damper and put some insulation on top of the damper in the duct to plug the hole. You will also need duct board adapters for the thickness of your duct board.

Erik Wnoroski
EWC Controls, Inc.
385 State Route 33
Englishtown, NJ 07726
800-446-3110 ext 483

[vaguy]

I'm reading recommendations on your web site under duct sizing of adjusting the travel limits on dampers to allow for a 20% leakage in large zones. Seems to me the 1" gap on a 9x12 would serve that purpose. Thoughts?

Do your ND and SID dampers all have adjustable travel limits?

[Erik W.]

The best way for you to do things is to use the end stops on the damper motor to set your leakage rate into your zones. All power open power close actuators have adjustable end stops.