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Differential Bypass Valve

The Taco Differential Bypass Valve provides an accurate and dependable means to control excess flow in zone valve systems that can be created when there is a reduction in the demand for heat. This reduced heat demand typically occurs as zone thermostats are satisfied and their corresponding zone valves close, causing the system pump to attempt to force more water through the remaining zones.


By installing a Taco Differential Bypass Valve between the discharge of the system pump and somewhere before the inlet of the pump--usually on the system return--you create an automatically regulated flow path. This regulated flow path prevents unacceptable velocities from being pumped through the zones that remain open during reduced demand periods.


Differential Bypass Valves should also be used to prevent dead heading of the circulator in systems where parallel piped heat emitters are controlled by thermostatic radiator valves.



  • Prevents Velocity Noise While Maintaining Desgined Heat Transfer of Each Zone
  • Enhances Overall System Perofmrance
  • Brass Body, Indicator and Union Nut
  • Stainless Steel and Engineered Plastic Internals
  • Maximum Pressure: 200 PSI
  • Maximum Temperature: 200 F
  • Adjustment Range: 0 to 7.5 PSI