Cooling/Heating Effects on Duct Sizing
Cooling/Heating Effects on Duct Sizing
(OP)
To calculate the fan cfm for my air handling unit should I use:
1. CFM=Qlatent/1.1/(Toutside-Tinside)
OR
2. CFM=(BuildingVolume)*(AirExchanges/hour)/60?
If I do use the first equation, then for different loads (coolong and heating) the cfm works out to be different. Should I size the ducts based on the larger cfm or the smaller? Thanks !
1. CFM=Qlatent/1.1/(Toutside-Tinside)
OR
2. CFM=(BuildingVolume)*(AirExchanges/hour)/60?
If I do use the first equation, then for different loads (coolong and heating) the cfm works out to be different. Should I size the ducts based on the larger cfm or the smaller? Thanks !





RE: Cooling/Heating Effects on Duct Sizing
RE: Cooling/Heating Effects on Duct Sizing
You can check for cfm based on total load by the equation Htotal = 4.5 x cfm x Enthalpy Difference.
Note: sensible heat = 1.08 (or 1.09) x cfm x Temp. Diff.
(either of these to values is sufficient in most of the cases)
RE: Cooling/Heating Effects on Duct Sizing
RE: Cooling/Heating Effects on Duct Sizing