Standard two-way and three-way mixing and diverting models are available as well as a unique three-way bypass configuration that switches between primary and bypass flow ports to prevent pump dead heading.
A durable, energy efficient 24 volt, three-wire actuator provides traditional two-position control action, or can be combined with any three-wire floating controller for outdoor reset on radiant systems. High electrical efficiency allows for nine valves on a standard 40 VA transformer. The 644 Series zone valves come in ½, ¾, and 1 in. sizes with NPT or sweat union connections.