FLEXIBLE DUCT CONNECTION TO METAL DUCT
FLEXIBLE DUCT CONNECTION TO METAL DUCT
(OP)
Square to round transition pieces are used at the end of duct branches to connect flexible ducting which then goes to the diffuser. Alternatively, a round dovetail joint neck is connected to the bottom of the duct to which the flexible duct connects that then connects to the plenum box of the diffuser.
Is there any particular preference for the square to round transition piece compared to just constructing a straight round neck?
Is there any particular preference for the square to round transition piece compared to just constructing a straight round neck?





RE: FLEXIBLE DUCT CONNECTION TO METAL DUCT
The transition will give you better flow by reducing this vena contracta.
A tapered reducer will have a similar effect.
If you are getting as much airflow as you want at the register I would not worry about it.
B.E.
RE: FLEXIBLE DUCT CONNECTION TO METAL DUCT
Flex ducts should run at a low veleocity (<3.5m/s max for noise) so even the pressure drop on the the index run should be very small and I would not bother with anything special.
RE: FLEXIBLE DUCT CONNECTION TO METAL DUCT
Get some SMACNA or ASHRAE volumes and read on fitting pressure drop.