bundysnake
29-09-2011, 08:02 AM
Does anyone know how to calculate return air grille size properly not using a rule of thumb method?
I know how to size duct etc but not return air grille size.
Let's say I have 2 x 18kw fcu's from different manufacturers both with the same airflow but one has a much higher static pressure, disregarding return air noise how does the FCU with the higher static pressure provide me with more flexibility when sizing my return air grille?
Usually I base my return size on an airflow velocity of 1.5m/s, if I increase this velocity at which point will it actually reduce airflow?
If anyone can help explain this I would much appreciate it :)
I know how to size duct etc but not return air grille size.
Let's say I have 2 x 18kw fcu's from different manufacturers both with the same airflow but one has a much higher static pressure, disregarding return air noise how does the FCU with the higher static pressure provide me with more flexibility when sizing my return air grille?
Usually I base my return size on an airflow velocity of 1.5m/s, if I increase this velocity at which point will it actually reduce airflow?
If anyone can help explain this I would much appreciate it :)