A differential bypass valve has been designed to control excess water in zone valve systems. To control excess flow and maintain an automatically regulated flow, the differential bypass valve is installed between the discharge of the pump and before the pump inlet, usually on the system return, the company says. The valve maintains a regulated flow path to prevent unacceptable velocities from being pumped through the zones that remain open during reduced demand periods. This prevents velocity noise, while maintaining the designed heat transfer of each zone, boosting overall system performance. According to the manufacturer, the valve should be used to prevent dead heading of the circulator in systems where parallel piped heat emitters are controlled by thermostatic radiator valves. Features include a maximum temperature rating of 200 degrees F, maximum pressure rating of 200 psi, an adjustment range of 0 to 7.5 psi, and an adjustable spring-loaded seat that opens and closes to allow flow through the valve.
Taco Inc., 1160 Cranston St., Cranston, RI 02920; 401-942-8000; 401-942-2360 (fax); www.taco-hvac.com.