RO System Maintenance: Diagnosing the No-Shut-Off Issue

RO Pump Troubleshooting: Addressing the No-Shut-Off Problem

　　In instances where your reverse osmosis (RO) system continues to run wastewater continuously without shutting off, even when the storage tank is full, it is essential to understand the role of the critical valves involved. This guide will help you identify and troubleshoot the issue.

Understanding the Valves

　　To address the no-shut-off issue, it’s important to recognize the three key valves that control the RO system’s shut-off function. Refer to the diagram below to locate these valves.

Electric Shut Off (ESO) Valve

　　This valve is responsible for shutting off the pump when the storage tank reaches its full capacity.

Tank Shut Off (TSO) Valve

　　The TSO valve’s role is to shut off the water supply to the tank once it is full.

Check Valve (Point E)

　　Located at point E, this valve helps build up pressure in the tank (up to 40psi), at which point the TSO valve will activate to prevent further water input. Subsequently, the ESO valve will also shut off, stopping the pump.

　　If any of these valves fail to function correctly, the pump and wastewater will continue to run without interruption.

DIY Troubleshooting Tests

Test 1: RO Shut-Off Function

1. While the RO system is producing water, the pump should be operational, and wastewater should be draining.
2. Close the tank valve to simulate a “tank full” condition.
3. If the RO system stops producing water, and the pump and wastewater cease to run, the system is shutting off correctly, and all valves are functioning properly.
4. If the pump and wastewater continue to run, the RO system is not shutting off. Further testing of the Check Valve and TSO/ESO valves is required.

Test 2: Check, TSO, and ESO Valves

1. Allow the RO system to fill the tank.
2. Turn off the cold feed water supply to the RO system.
3. Open the tank valve.
4. Remove the RO system’s black drain line from the drain pipe.
5. Inspect the black line for any water drainage.

　　If water is draining from the line, the Check Valve is faulty and needs replacement. If no water is draining, the TSO and/or ESO valves may be the issue and should be replaced.

Check Extra Output Points

　　If your RO system supplies water to multiple points (e.g., icemaker, coffee maker), ensure that all output lines and T-fittings are airtight and free of leaks. Any leaks can prevent the system from building pressure, resulting in the RO system’s failure to shut off.

Addressing System Depletion

　　Continuous water drainage can deplete the stages 1, 2, and 3 prefilters. If the RO system fails to shut off for more than 3-4 weeks, it’s advisable to replace these prefilters to protect the membrane. Additionally, test the membrane’s condition with a TDS meter to ensure it remains in good condition.

Yearly Maintenance Tips

　　Changing the three prefilters at least every 12 months is crucial to maintain the system’s efficiency and prevent damage to the stage-4 membrane and shut-off valves.

Water Flow Through the RO System

Input to Output: A Detailed Look

　　Here’s how water flows through the RO head:

• A: Input water enters the stage-1 sediment filter at point A.
• ESO: From A, water flows into the Electric Shut Off (ESO) valve.
• P1: Water moves into the booster pump at port P1.
• P2: With increased pressure, water exits the pump at port P2 and enters stage-2 filter.
• B: Water passes through stages 2 and 3 filters, exiting stage-3 at port B.
• D: From B, water enters the Membrane housing at point D.
• W: Waste water from the membrane drains out through point W to the drain pipe.
• E: Pure water exits the membrane housing at point E.
• Check Valve: An internal Check Valve at point E prevents backflow into the RO system and aids in the shut-off process when the tank is full.
• T1, T2: Pure water from point E enters the TSO Tank Shut Off valve at T1 and exits at T2.
• TSO: The TSO valve shuts off the tank when internal pressure reaches 40psi.
• F, G: Pure water flows through points F and G, entering the pressure tank.
• H: When dispensed, pure water exits the tank through the Yellow line, passes through the Stage-5 filter at point H, and flows to the RO faucet.

　　By following this guide and performing regular maintenance, you can ensure your RO system operates efficiently and effectively, providing you with clean, pure water.