Need some help with RO/DI unit...

kschweer · Apr 26, 2012

I installed an rodi system today and I am having some issues. I have an auto shut off valve hooked up. The house has a pressure pump to increase water pressure throughout the house. The issue I am running into is that when the auto shut off valve starts to shut off the homes pressure pump kicks on and puts the pressure back on the RO unit. Has anyone ever ran into this? Or does any lone have any input. Any help would be greatly appreciated.

cdness · Apr 26, 2012

This is a new one... So are you saying the house booster pump is putting enough pressure on the RO unit to keep it running?

When the float switch causes some back pressure the switch part should close off the supply line to the RO unit itself so the pressure would be behind the shut off valve.

What does the pressure guage on the RO say when it is filtering water and when the pump kicks on? I know they have a rating but I am unsure on the pressure they can handle.

kschweer · Apr 26, 2012

The shut off valve starts to shut of and as it does the homes pressure pump kicks on and the pressure in the system goes back up. When running the gauge reads 92 psi.

kschweer · Apr 26, 2012

Do you think there is too much pressure causing the auto shut off valve to not work properly?

AZDesertRat · Apr 27, 2012

Place a 1 psi check valve in your tap water feed line anywhere before the RO membrane, I would place it after the carbon block myself so it stays cleaner. This will prevent the pressure spike or water hammer associated with an ASOV closing.

kschweer · Apr 27, 2012

Thank you I will try the check valve. Can you explain to me what is going on just so I have an understanding? Also can you explain why the check valve will solve the problem? I just want to know what's going on. Thanks again.

AZDesertRat · Apr 27, 2012

You are experiencing water hammer or ocillations of pressure in the line as the ASOV shuts off. Water hammer is not only high spikes but also valleys athe the water oscillates back and forth. the low presure spikes call the pump to start.
Another thing that would work and possibly better is a pressure, bladder or captive air tank on the RO/DI. Water does not compress so water hammer can be severe but provide a pressure tank and you now have an air cushion which does compress and dampen the oscillations.