RE: Manual dampers – Vertical mounted or Horizontal?
When installing manual dampers into long sections of solid duct work does it make any difference whether you mount them vertically verses horizontally? If you mount them vertically and have them positioned on an angle. Does this increase air flow into that section of duct?
No, I always mount them so that the handle’s are the most accessible. The pressure drop due to the damper should already be accounted for in the design (if done correctly).
They may act as a little bit of a scoop if they extend in the duct-work, but theoretically the only damper that should be full open on most duct systems is whichever run carries the design resistance (longest Total Equivalent Length), all other dampers will probably need to be closed off slightly.