RO Pump – Troubleshoot Guide- No Shut-Off

Byadmin6688

　　Interviewer: Good morning! Today, we’re tackling a common issue faced by many RO pump users – the problem of the pump not shutting off. Can you walk us through the diagnostic steps you’d take to resolve this specific issue?

　　When the RO system continuously discharges wastewater and fails to shut off even when the tank is full, it’s essential to understand the role of three key valves in the shut-off mechanism. For a visual reference, please refer to the diagram below to locate these valves. Firstly, there’s the Electric Shut Off (ESO) valve, which is responsible for stopping the pump when the tank is full. Next, we have the Tank Shut Off (TSO) valve, which halts the water flow into the tank once it’s full. Lastly, the Check Valve, located at point E, helps to build up pressure within the tank to 40psi, signaling the TSO to shut and subsequently the ESO to turn off the pump. If any of these valves malfunction or fail to close, the pump and wastewater will continue to run endlessly.

　　To diagnose the issue, you can perform two tests:

  1. Testing the RO’s Shut Off Function:
  • Observe the pump in action while the RO is producing water and wastewater is draining.
  • Manually close the tank valve to simulate a "tank full" scenario.
  • If the RO ceases water production, and the pump and wastewater stop flowing, it indicates that the RO is shutting off correctly, and all valves are functioning properly.
  • If the pump and wastewater continue to flow, it suggests the RO is not shutting off, necessitating a test of the Check Valve and the TSO/ESO valves.

  1. Testing the Check, TSO, and ESO Valves:
  • Allow the RO to fill the tank.
  • Turn off the cold feed water supply to the RO.
  • Open the tank valve.
  • Disconnect the RO’s black drain line from the drain pipe.
  • Inspect the black line for any water drainage.
  • If water is draining, the Check Valve is faulty, allowing backflow into the drain line. Solution: Replace the Check Valve.
  • If no water is draining, the Check Valve is functioning correctly, and the issue likely lies with the TSO and/or ESO valves. Solution: Replace the TSO and ESO valves (contact us for assistance).

  1. Checking for Additional Output Points:
  • If your RO system supplies water to multiple outlets (e.g., icemaker, coffee maker), ensure all output lines and T-fittings are airtight and leak-free. Any leaks can prevent the RO system from building up pressure, causing it to fail to shut off.

　　[End of Test]

　　Please Note: A failed RO shut-off can lead to the depletion of the stages 1, 2, and 3 prefilters. If the RO doesn’t shut off for more than 3-4 weeks, it’s advisable to change these prefilters to protect the membrane. Additionally, test the membrane’s condition using a TDS meter if available to ensure it remains in good condition. Remember to change the prefilters at least every 12 months to prevent damage to the stage-4 membrane and shut-off valves.

　　Water flows through the RO head as follows:

  • 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 then enters the booster pump at port P1.
  • P2: With increased pressure, water exits the pump at port P2 and enters the stage-2 filter.
  • B: Water passes through stages 2 and 3 filters and exits the stage-3 filter 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.
  • 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 from T2 passes through points F and G and enters the pressure tank.
  • H: When pure water is dispensed, it exits the tank through the Yellow line, travels through the Stage-5 filter, and exits at point H, flowing to the RO dispensing faucet.

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