The Watts A200 is a unique new design which assures delivery
of water to the trap to assure against evaporation of the water
seal. No. A200 operates by the water flow acting against the
main reaction disc (1), which forces the reaction disc in the
upward position and removes the trap disc (2) from the plastic
trap seat (3). A spurt of water is then delivered to the trap.
However, with increased flow, the main reaction disc (1) continues to lift and seals off the closing disc (4) to stop flow
to the trap. When the flow through the valve is stopped, the
trap disc (2) is returned to the closed position, and in the process, delivers a spurt of water to the trap before closing off.
The importance of this design is that a complete flow cycle through the valve from open to close will actuate the primer twice with two definite pulses; once on opening and once on closing, thus providing a tremendous water savings over competitive models. This is an exclusive Watts feature.