duct esp

[pramodpatil]

what is meaning of duct esp. how to calculate?

[MrMark]

I am going to guess the term is duct "external static pressure", and if it is, it means the added resistance to air flow caused by any duct work attached to the air handler.
Equipment manufacturers rate their equipment based on how it is shipped. If no additional inlet or discharge duct work is required, then the volume flow rating will be as indicated. In some cases, additional static resistance needs to be added to the system in order to assure the fan motor does not overload. This additional resistance is sometimes indicated as "duct esp".