Decoupled Loop
Bypass Flow Tracker
Audit bridge flow rates between primary chiller loops and secondary building distribution loops to ensure hydraulic neutrality.
Understanding Primary-Secondary Pumping & the Decoupler Bridge
The “decoupler” or bridge pipe is a short, low-resistance segment connecting the primary chiller loop and the secondary building distribution loop. It allows each loop to operate with its own independent flow rate. If the primary loop flows faster than the secondary, water moves through the bridge in one direction; if the secondary flows faster, water moves the other way. This bridge is the “neutral” zone that prevents pumps from fighting each other. If this bridge is not properly calibrated, chilled water from the return side can “short-circuit” back to the supply side, severely diluting the system’s thermal efficiency.
Frequently Asked Questions
A: A high bridge flow indicates the system is severely mismatched. It means the secondary loop isn’t utilizing the full chilled water capacity, or the primary pumps are over-pumping. This causes the leaving chilled water temperature to be artificially high, which sends a false load signal to the chiller, forcing it to run inefficiently.