A pressure reducing valve (PRV) automatically decreases high incoming water pressure to a safe, regulated downstream pressure suitable for building plumbing and HVAC systems. These valves maintain consistent outlet pressure between 40-80 PSI regardless of fluctuations in supply pressure. PRVs protect pipes, fittings, and appliances from damage caused by excessive pressure exceeding manufacturer specifications.
Operation and Settings
The valve uses an internal diaphragm and spring mechanism that opens and closes to maintain set pressure. Adjustable models allow field tuning from 25 to 100 PSI using a screw on the valve body. Flow capacities range from 10 to 100 gallons per minute depending on valve size, typically 1/2 inch to 2 inches in diameter. Relief ports discharge excess pressure safely to prevent backpressure conditions.
HVAC System Applications
PRVs are essential on boiler fill lines where supply pressure exceeds 12 PSI. Chilled water systems, solar thermal loops, and radiant heating circuits benefit from pressure regulation. Codes often require PRVs where supply pressure exceeds 80 PSI to protect system components rated for lower pressures.
Maintenance Requirements
Periodic inspection of relief ports ensures proper drainage. Sediment buildup requires occasional flushing of filter screens. Pressure gauge installation downstream of the valve monitors performance and indicates when replacement is needed.