Help, My RO Auto Shut-Off Valve Has a Problem and Isn’t Working!
Written by: Gene Fitzgerald // Last Updated: Aug 25, 2023
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Don’t panic!! It is not a big scary fix if you have a broken or faulty ASO valve.
In fact, once you have established the issue and decided to repair/replace your ASO valve, you can do so pretty easily!
Here’s why your RO auto shut-off valve could not be working and how to fix it.
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Key Takeaways
There are several reasons why your ASO valve might not be working, including improper installation, a stuck diaphragm, or downright failure.
- If the valve is plumbed in wrong, disconnect and reconnect it.
- Disconnecting can also help when the diaphragm is stuck.
- Most of the time, a broken RO auto shut-off valve cannot be repaired but only replaced. Follow the instructions in this guide to check if your ASO needs replacement and how to do it.
Why Your RO Auto Shut-Off Valve Is Not Working
So, why is your RO auto shut-off valve not working?
The automatic shut-off valve of a reverse osmosis systems works by monitoring the feed water and RO tank pressure. When the pressure in the RO storage tank reaches ⅔ of the feed water pressure, the ASO valve closes and shuts off the water flow, ensuring your system does not constantly run. However, there are a few reasons why it may have stopped working.
Plumbed in Wrong
This may happen if one or more of the valve connections is faulty. It may be a manufacturer issue, or it may be that a mistake has been made when installing the ASO valve. If this happens, it can cause the RO system to run without filling up the tank. To troubleshoot, check all the connections. You may need to disconnect and reconnect the ASO valve.
Your ASO Is Stuck
Sometimes the ASO gets stuck in the closed position, and no new water can enter the RO system. This problem can be solved by disconnecting the ASO valve to release pressure and reconnecting it.
Your ASO Is Broken
A broken ASO means the system will not shut off when the RO tank is full, causing a lot of wasted water. If you have a broken ASO, you must replace it with a new one.
How to Check If Your RO Shut-Off Valve Is Broken
Here’s how to test if your RO system’s ASO valve is functioning properly:
Test #1
- Ensure the storage tank is full by attempting to lift it.
- Dispense 2-3 glasses of water from the RO faucet, lowering the storage tank’s pressure and causing the system to refill.
- Shut the tank valve to imitate a full tank.
- Wait for 5 minutes.
- Determine whether water ceases to flow down the drain line by listening or detaching the drain line from the drain saddle. If the flow stops, both valves are functional. If not, the automatic shut-off or check valve is defective. Proceed to Test #2.
Test #2
- Let the tank refill.
- Keep the tank valve in an open position and switch off the feed water valve.
- Examine if water is draining by listening or disconnecting the drain line from the drain saddle. If water continues to drain, the check valve is damaged and requires replacement. If there is no water flow, the ASO valve is malfunctioning and needs to be replaced.
Further Reading:
How to Replace a Broken Automatic Shut-Off Valve
- Before working on your RO system, turn off the water supply and storage tank valve. Then, drain the system by running the RO faucet.
- Locate the ASO valve, which has four connection ports.
- Take a minute to observe which tubes are associated with which inlet so that you can reconnect it correctly.
- Detach the old ASO valve from the tubing.
- Attach the new ASO valve to the appropriate water inlet and outlet tubes, and make sure the connections are secure.
- Turn on the water supply to the RO system and check the ASO valve connections for any leaks. If leaks are found, deactivate the water supply and reposition the tubing connections before retesting.
- After ensuring no leaks exist, allow the RO system to run to check that the ASO valve operates correctly and halts water flow when the storage tank is full.
If you have any questions about your RO auto shut-off valve not working please don’t hesitate to leave a comment below!
About the Author Gene Fitzgerald
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