ASO not working on RODI - help!

[discocarp]

Ok I'm stumped. My RODI is constantly making waste water. I ordered a new ASO, triple checked the hookups (99% sure theyre right). Even with the output line shutoff the unit continues to produce waste water. I am out of ideas on what to check. Please help!

[BeanAnimal]

It may take a day or so for the ASOV to work. On a new RO/DI unit, there is a lof of air in the media and system. The air will eventually compress and work it's way out.

The ASOV will still take a few minutes to "shut off" each time the unit is used. Depending on the input pressure, the "few minutes" could be as many as 10-15.

Bean

[skuykend]

Could there be lots of air trapped in the system someplace? This could trick the ASOV for a while. Also, you may try to hook up the ASOV by itself to make sure it's working properly... Hook up the supply line to a tee, then directly to both inputs and put a valve on the pure water output of the ASOV and see if it shuts off.

Steve

[discocarp]

The system isn't new, I just replaced the aso since it stopped working. I'll try to give it more time to shutoff and see, but I think its still just not working. Letcha know in an hour. :P

[discocarp]

Thanks I'll try to test just the new (and old) ASOs shortly. I'm gonna let it run for awhile to see if it will shut itself off if I wait longer first.

I'm just really stumped since the old ASO was doing the same thing. It seems to me something else in the setup must be causing the problem, but what that is I have no idea...

[skuykend]

If the presure on the pure water out isn't getting to the point where the ASOV will shut off.... maybe the membrane busted to where ALL the presure is going to waste out? Does the unit seem to make good water when it's running?

[discocarp]

The unit makes perfect water when its running, and I recently (2 weeks or so) replaced the membrane/restrictor as well (problem was with old and new). I get a 4-1 ratio of permeate/waste when the unit is on.

FYI, the unit is still making waste water an hour later with all outputs closed.

Next step is to test both aso valves I guess. And I'll run the unit manually like I have been for a bit longer hehe. I really hope I can get this sorted out.

[discocarp]

Both aso's work on tap pressure. Best I can tell there's no air in the unit. Any other ideas? This is really stumping me.

[BeanAnimal]

Did the asov ever work after membrane change? If not let it run overnight...it may stop.

Bean

[discocarp]

I changed the membrane about 2 weeks ago after noticing the problem (needed to be changed anyway, so was first thing I tried). Didn't fix it, and a new aso has not fixed it. The old aso ran over 24 hours (after membrane change) and still had the problem. New one was just installed today. I'll make a bunch of RO tonight and see where it stands tomorrow, but I don't think it will fix things (didn't with the old aso, but worth a shot on the new one).

[discocarp]

Oh one more thing. I checked the pressure after sed+carbon and its at about 60 psi, which was (roughly) the same as it was ages ago when it did work.

[Unresistible Blue]

There are two common problems with ASO function. First is caused by air trapped in the ASO. With the unit running, carefully lift the unit off the wall, and tilt it so the in/out ports on the ASO are vertical rather than horizontal. Shake it a bit and see if you can dilodge the air trapped in the ASO.

The next most common problem is a failed check valve. The valve is located between the permeate port on the RO housing and the ASO.

Blue

[discocarp]

I'm pretty sure the unit (including the aso) doesn't have air trapped in it. I've wiggled, shook, etc. hehe.

The check valve is a great idea. I never even thought to check that! I'll replace both check valves. I know you just mentioned the check valve after the permeate output on the membrane, but do you think I should just replace the check valve before the drinking water kit as well? I figure I might as well do em both. They're old, cheap to replace, and notorious for failure over time hehe.

[discocarp]

Bingo! It was the check valve! Thanks sooo much for your help! I don't know how long it would of been before I figured that one out for myself. :)

[Unresistible Blue]

Whoo Hoo!