Curious about duct sizing
Curious about duct sizing
(OP)
Hi all,
I have noticed in restaurants and bars (those with open ceilings) that the ducts that travel throughout go so far and then reduce in diameter for another distance, and, depending on the required length, they may reduce again. All the while having vent outlets either directly on them , or a duct that branches out each way an equal distance.
I know nothing about this , but I assume this is to keep an even output through all vents over the lenght of the duct distributing the air / heat. Is this correct? If not, why is this done?
Just wondering and thanks,
Scott
I have noticed in restaurants and bars (those with open ceilings) that the ducts that travel throughout go so far and then reduce in diameter for another distance, and, depending on the required length, they may reduce again. All the while having vent outlets either directly on them , or a duct that branches out each way an equal distance.
I know nothing about this , but I assume this is to keep an even output through all vents over the lenght of the duct distributing the air / heat. Is this correct? If not, why is this done?
Just wondering and thanks,
Scott
In a hundred years, it isn't going to matter anyway.





RE: Curious about duct sizing
The most commonly used method of duct sizing is equal friction method, in which, a cetain fixed pressure drop is considered for 100' length of the ducting. When you open an outlet, the flow in the succeeding duct reduces and thus the pressure drop. So, you can reduce the duct size to maintain constant pressure drop.
RE: Curious about duct sizing
I have been in discussions with contractors on whether, considering there are no expensive fittings, the extended plenum is less expensive to build.
RE: Curious about duct sizing
RE: Curious about duct sizing
RE: Curious about duct sizing
Worked like a charm, balanced like a charm.
RE: Curious about duct sizing