Need Release Air Trapped in Check Valve
If your RO system makes a whining or humming noise, most likely it's due to air that got trapped in the "Check Valve" during installation. So we need to get rid of the air in the Check Valve.
The Check valve is on the left side of the Membrane Housing (see Fig. Step2). It is an internal valve encased in an L-shaped plastic fitting. It connects to the Clear line that puts out pure water from the Membrane housing.
To relief the air bubbles, do as follows: (See Pictures Below)
- Step 1: Close the Tank's valve.
- Step 2: Tilt the RO system to the right. Put something under the 3rd filter housing to keep RO tilted. This will help dislodge the air bubbles from the Check Valve.
- Step 3: Turn on the RO spigot. Let pure water flow thru spigot for about 1 minute. This forces the air to flow directly out to the spigot, bypassing the tank.
- Step 4: Turn off the spigot. Wait for about 10 seconds. Repeat step 3 again. Do that 3- 4 times, until noise goes away.
When noise is gone, open the Tank valve again, and let RO run as usual.
If the noise comes back, try the above procedure again another 2-3 times. Sometimes it takes several tries to get rid of all the air in the system.
If noise remains after a few days, that means either there is air in your water source, or the current Check Valve is resonating with your water pressure and pipes, creating the noise. In this case, a new Check Valve will solve the problem.