Inspect the disc holder and stem guides, located on the top of the backflow device, for foreign debris. An obstruction which prevents the discs or stems from moving freely might cause the relief valve to discharge continuously during a no-flow condition. Clean the disc holder and stem guides with a clean cloth.
Ensure that the center bolt on the main stem does not exceed 15 inch-pound torque using a torque wrench. A jammed main stem due to excessive torque may cause the relief valve to discharge continuously during flow and no-flow conditions. Excessive center bolt torque can also damage other components of the backflow prevention device.
Inspect the diaphragm retaining screw for leakage. If leakage is present, extract the screw using a screwdriver, and apply a layer of sealant on all the threads. Reinsert the screw. An improperly sealed diaphragm retaining screw can cause discharge from the drain hole in the relief valve spacer.