Duct Calculator: HVAC Sizingv1.1.0

What changed

• New featureAdded duct material selection (Galvanized, duct board, flexible) which adjusts calculations based on ASHRAE roughness.
• New featureNew 'Check' tab to calculate velocity, friction rate, and airflow for existing duct dimensions.
• UXUser-defined friction rates now persist when switching between supply and return modes.

Original release notes

Duct material now changes the answer. Galvanized, duct board and flexible duct each
carry their own ASHRAE roughness, and flex needs a full standard size more than metal
at the same airflow. Size a flex run as if it were metal and it always goes in over
its design friction rate, by up to double.

New Check tab for the duct that's already there: type in a round diameter or a width
and height and read back its velocity, its friction rate, and the airflow it will
actually carry, with a verdict against whichever limit binds first.

Also: a friction rate you type in now survives switching between supply and return.
Manual D designs a whole system to one rate, so the per-service defaults no longer
overwrite a number you worked out yourself.