hi friends
i have got 4 A.H.U with differnt capacity , what is recomended velocity i must used to size pipe for each unit ,and main pipe ,is it same FOR F.C.U?
if i want to add A.H.U or F.C.U in the future what is factors i must put in the consideration when i add new branch ?
what is equation i must used to select flow rate of circulating pumps for this A.H.UNITS ,is it summation for all A.H.UNITS ?

THANKS FOR EVERY ONE HELP.