Plunger or piston style ballcocks are among the earliest style of toilet tank fill valves and are made of a heavy duty cast brass body typically providing quiet operation. This style of ballcock uses a characteristic bottom-fill water discharge tube and is designed with a hinged lever assembly above the ballcock which often use thumbscrews at some hinged joints to allow adjustment of lever arm movement.
How it Works:
Plunger ballcocks are actuated by a brass float rod and ball attached to a lever which moves a plunger or piston in the ballcock body up or down to start or stop the flow of water to the tank through the water discharge tube. The plunger uses an O-ring or leather washer to form a seal to prevent the water from leaking out the top of the fill valve. As the water level in the tank rises and falls, the float rod and ball move the lever arm accordingly. When the water level is at the correct height, the plunger is fully seated in the fill valve body and stops the flow of water to the tank. When the toilet is flushed, the water level in the tank drops and the lever assembly move the plunger up allowing water to fill the tank again.
The de facto standard in early plunger style fill valve was the Mansfield 09 with many still in service today. In 2007, Mansfield’s brass division was purchased by Prier, an excellent quality brass plumbing and industrial products manufacturer. The Mansfield 09 is still manufactured by Prier but the ballcock is not listed as anti-siphon by the manufacturer. Wolverine Brass makes a similarly styled anti-siphon ballcock called the Wolverine Model 50568 (10”) or the Model 50569 (12”) They also make an adjustable height anti-siphon plunger ballcock, Model 56568. Cesco Brass also makes a similar style anti-siphon plunger ballcock called the Burlington 20A
There really isn’t any high tech way to adjust the water level with a plunger ballcock. You simply bend the brass float rod gently upward to increase the water fill level or gently downward to lower the water fill level. The plunger / piston mechanism should be a minimum of 1 inch above the top of the overflow tube in the tank, and the overflow tube must be below the height of the toilet tank handle which actuates the flush valve releasing the water.