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PWSRTA Control Valve System Description
The PWSRTA control valves consist of the following components:
1. Drive Assembly
2. Drive Cap Assembly, Main Piston and Regenerant Piston
3. Spacer Stack Assembly
4. Injector Cap, Screen, Injector Plug and Injector
Drive Assembly
The drive assembly consists of the following parts:
• Drive Bracket
• Printed Circuit (PC) Board
• Motor
• Drive Gears
• Drive Gear Cover
The drive bracket holds the PC board, the motor, the drive gears and the drive gear cover in place.
The PC board receives and retains information, displays the information, determines when to regenerate and initiates regeneration. The display
shows different types of information in the initial system set up (for softeners or filters), installer display settings, diagnostics, valve history or
user display settings.
The PC board powers the motor. The PC board's two-prong jack connects wires to the direct current (DC) motor. The motor is held in place on
the drive bracket by a spring-loaded clip and a small bulge in the plastic, which fits in one of the slots on the motor housing. The motor turns
drive gears that drive the piston to cycle positions for backwashing, regeneration, rinsing, refill or service. The motor is fully reversible (turns
both ways) and changes direction of rotation to change the direction of piston motion. The motor is easily replaced if necessary.
There are three drive gears held in place by the drive gear cover. All three drive gears are the same size. A reflective coating is applied to the
gears. As the center drive gear turns a light shines on the coating and a light sensing diode determines if a light pulse was returned. The PC
board counts the pulses and determines when to stop driving the motor.
Drive Cap Assembly, Main Piston and Regenerant Piston
The drive gears turn the main gear of the drive cap assembly, which moves the piston. The screw-driven, horizontally moving piston stops at
specific positions to direct the flow of water to backwash, regenerate, rinse or refill. The PC board determines the position of the piston by
counting pulses produced when the piston is moved. An optical sensor looking at one of the reduction drive gears generates these pulses.
Each cycle position is defined by a number of pulses. The counter is zeroed each time the valve goes to the service position. The PC board
finds the service position by noting the increase in current delivered to the motor when the mechanical stop at the service position is reached.
This method of controlling piston position allows for greater flexibility and requires no switches or cams (U.S. Patent 6444127).
One of two main pistons is always used:
1. A 1.25" diameter downflow piston is used when the PWSRTA control valve is used as a downflow softener, regenerating filter or non-
regenerating filter.
2. A 1.25" diameter upflow piston is used when the PWSRTA control valve is used as an upflow softener. Upflow option not applicable for EA,
EE or EI control valves.
If the control valve is used as a softener or a regenerating filter, a regenerant piston must be attached to the main piston. If the control valve is
to be used on a system that does not require a regenerant to be added, the regenerant piston must be removed.
PWSRTA Twin Alternating Series Softeners
5. Refill Flow Control Assembly or Refill Port Plug
6. Drain Line Flow Control and Fitting Assembly
7. Water Meter
8. Twin Transfer Valve
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