Quote Originally Posted by regis101 View Post
Thankx dash.

I am under the assumption that the length(s) of the ducting is part of, not just the reason, of the Man D to help get the airflow down to the rooms requirement.

As dash mentioned, a shorter run will get more air. So this means a longer run will slow it down? If so, will having to take a branch line from 20ft as drawn down to 8ft affect the airflow as described for that room.
Man. D determines he friction rate,which determines the duct size based solely on the longest return and supply air path.So all the shorter runs tend to get more air.Man. D suggests that balancing dampers be installed at each branch take-off,to allow for adjustment due to this.

We find that the dampers at the supply grilles will take care of any required balancing.

So yes yes,shortening it will have a minor increase in air flow,likly not an issue with proper design,in all other aspects of Man. D.