RO/DI filter making whining noise

[Pdandy]

I have my RO/DI unit plumbed directly to my sump with a float for top-off. (yes, I know this isn't ideal. But I have measures in place to alert me to a failure and possible flood that would ensue.)

My question is that my RO unit makes a whining noise when the float drops just enough to start making water. If I shut the RO unit off completely and let some water evaporate from the tank it won't make this noise when I turn it back on as it is refilling a larger volume. It only does it when it is just barely dropping below the float.

Any ideas of what is causing this? A lose fitting on the filter? Something to do with the pressure in the lines?

 

[twilliard]

The auto shut off valve typically chatters

 

[Pdandy]

The auto shut off valve typically chatters

That's probably it then. It is right at the point of shutting off and it is chattering. Is there a way to stop that from happening?

 

[twilliard]

Not from my experience they work off of back preasure.

 

[AZDesertRat]

A high pitched noise is normal.
The way you have it hooked up is the absolute worst thing you can do for your RO/DI though. Short spurts kill the membrane and wipe out the resin in no time at all. Membranes must be flushed with nice long filter runs in excess of 5 treated gallons so they stay operable. Please reconsider your set up, not do much because ofvthe potential for a flood which will happen almost guaranteed but so TDS creep doesn't ruin not only your membrane and DI but also the effects on your tank. Just to prove a point, measure the TDS of those short spurts with a handheld TDS meter and I am sure you will agree.

 

[twilliard]

Hey now my float has been running 6 plus years strong :)

 

[AZDesertRat]

I will bet money you would quadruple your membrane and DI life if you set the same system up with float switches and a solenoid valve set 4-6 inches or more apart so you get nice long cleansing filter runs. This is the same reason why drinking water type pressure tanks are a bad idea when making RO/DI. Short filter runs are the death of membranes and resin. As I said before measure the TDS with a handheld meter and you will be disappointed.