Primary-Secondary Pumping Rule of Thumb
Primary-Secondary Pumping Rule of Thumb
(OP)
A rule of thumb says that the location of the secondary pump in a primary-secondary piping arrangement shall always be in the supply piping of the secondary loop pumping away from the common pipe or decoupler, and the expansion tank shall be located in the return piping of the secondary loop upstream of the connection with the decoupler. What would happen if we connect the secondary pump in the return piping of the secondary loop, between the expansion tank and the connection to the decoupler, pumping into the decoupler?





RE: Primary-Secondary Pumping Rule of Thumb
RE: Primary-Secondary Pumping Rule of Thumb
If we place the secondary pump where you mention, what's to stop the secondary flow volume from driving through the primary loop? With that setup, why have a primary loop that maintains constant flow through heat exchange devices?
Basic application - a secondary loop pump often has a VSD to maintain a fixed loop differential (that way, the right flow and Cv can be anticipated through controlling devices). How will a 2° loop pump maintain that 2° loop DP when a disproportionate amount of its discharge volume might be driven through idle primary devices??
Chew on that a minute, then feed back. -CB
p.s., 1° = primary, 2° = secondary…