RO/DI wont stop producing waste water

[amnesiac]

Would greatly appreciate some help on this. My RO/DI unit will not stop making waste water. I've inspected the check valve and it seems fine. I've replaced the auto stop valve so I know that's not the issue. Actually, I don't think the first auto stop valve was bad either. Anybody got an idea where I should start trouble shooting next??? Thanks guys

 

[Greybeard]

The auto shut off valve should close when back pressure from the filtered water outlet reaches that of incoming water pressure. I had 2 of these fail on me some time back, honestly, I don't trust them, or use one anymore. Still, if you've replaced it, it would seem to me as if something may be wrong with your plumbing.

Is this a brand new unit, or one that worked for some time, and recently stopped shutting itself off? The new unit I received a few months back was assembled right, but mis-labeled from the manufacturer. In was labeled out. I won't mention the maker... he went over and above making it right. Anyway, it's quite possible, if it's a new unit, that it was not plumbed correctly. Everyone makes mistakes.

 

[username in use]

Are you sure it is all plumbed correctly? Can you post a pic of the setup?

 

[amnesiac]

I had never had issues before but never had to utilize the automatic shut off function. I just shut the water off from the source and called it a day. But recently I set up a 50 gallon reservoir with a float switch just in case I forgot to shut off the source water and of course, when I tested it that's when I found that the unit had a problem. From what I've been able to find it is plumbed exactly the way it should be. The manufacturer's diagram matches other diagrams I've found online so theres no issues there. I'm really at a loss.

 

[flananuts]

Do you have a valve before your drum? If you do close it and then listen for your ASV to **** off. It it's not then you know. I had to replace mine because I was measuring 40-50 ppm TDS post RO. The valve failed and waste water was pushing past.

 

[amnesiac]

Here's a couple of pics. Nevermind the color on the lines. I was running short on 1/4 tube so I had to get creative. Far as I can tell it's plumbed correctly.

 

[username in use]

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[fishgate]

 

[jmc1974]

Ok, let me try to help here... as plain as I can;

In order for the auto shut off valve to work correctly, you need a bladder tank, so the pressure from the water stored on the tank can help close the diagram. If you only close the valve after the last filter (carbon or di) it wouldn't be able to get it close. Not enough back pressure. As the bladder can build equal pressure as the source.

Use a tank even if you have a storage bin with a float, the float alone won't stop the RO from continuing to send water to the drain. Also this is a reason why RO membranes go bad so quickly, most should last 3-5years and more, but when not properly installed they get damaged.

FYI: I've been working in water filtration for the last 12 years and I'm WQA certified.

 

[reef_aholic]

Ok, let me try to help here... as plain as I can;

In order for the auto shut off valve to work correctly, you need a bladder tank, so the pressure from the water stored on the tank can help close the diagram. If you only close the valve after the last filter (carbon or di) it wouldn't be able to get it close. Not enough back pressure. As the bladder can build equal pressure as the source.

Use a tank even if you have a storage bin with a float, the float alone won't stop the RO from continuing to send water to the drain.

FYI: I've been working in water filtration for the last 12 years and I'm WQA certified.

My float, when it closes on my RODI system shuts down the entire flow to everything.

OP, is there a chance its a faulty switch?

 

[jmc1974]

My float, when it closes on my RODI system shuts down the entire flow to everything.

OP, is there a chance its a faulty switch?

If you have low water pressure coming in the float might close it, but when it is the last time you seen the drain line flow? Most people would never notice the RO keeps draining slowly after the float closes, here in my house the incoming pressure is between 100-110psi. (Yes this is high) I don't know why is so high, mostly in the area is about 80psi, so being that high the auto shut off won't close unless a tank is installed. But on my old apartment the water pressure was about 40psi and the auto shut off would close just with a valve/float.

 

[fishgate]

If you have low water pressure coming in the float might close it, but when it is the last time you seen the drain line flow? Most people would never notice the RO keeps draining slowly after the float closes, here in my house the incoming pressure is between 100-110psi. (Yes this is high) I don't know why is so high, mostly in the area is about 80psi, so being that high the auto shut off won't close unless a tank is installed. But on my old apartment the water pressure was about 40psi and the auto shut off would close just with a valve/float.

??? Are you taking into account the shutoff switch that comes after the membrane and before the float shutoff in the storage container? See my diagram above. What is listed is all you need. I am not sure the reason for the 2nd storage (bladder) tank.

 

[username in use]

here in my house the incoming pressure is between 100-110psi. (Yes this is high)

That's high enough to wear out your shower and faucet valves and cause everything to constantly drip.

 

[Shaummy]

Ok, let me try to help here... as plain as I can;

In order for the auto shut off valve to work correctly, you need a bladder tank, so the pressure from the water stored on the tank can help close the diagram. If you only close the valve after the last filter (carbon or di) it wouldn't be able to get it close. Not enough back pressure. As the bladder can build equal pressure as the source.

Use a tank even if you have a storage bin with a float, the float alone won't stop the RO from continuing to send water to the drain. Also this is a reason why RO membranes go bad so quickly, most should last 3-5years and more, but when not properly installed they get damaged.

FYI: I've been working in water filtration for the last 12 years and I'm WQA certified.

I'm sure you are very qualified, but I don't have a bladder tank on my system, and if I close the DI output, the water will rise in the DI canister and eventually cause the back pressure needed at the ASOV and it shuts down.

It can take a couple of minutes to close up...but it does close.

 

[jmc1974]

I'm sure you are very qualified, but I don't have a bladder tank on my system, and if I close the DI output, the water will rise in the DI canister and eventually cause the back pressure needed at the ASOV and it shuts down.

It can take a couple of minutes to close up...but it does close.

Like I said, if you feed pressure is low the build up inside the system sometime is enough to close , but if you have high feed pressure it will not. The original question was about why it didn't closed, so my answer was that it needed a tank to properly build enough back pressure to compensate for the incoming water pressure.

Just my .02 cents

 

[jmc1974]

??? Are you taking into account the shutoff switch that comes after the membrane and before the float shutoff in the storage container? See my diagram above. What is listed is all you need. I am not sure the reason for the 2nd storage (bladder) tank.

Yes, I did follow your picture and that is correct, the RO water enters the Tank side of the auto shut off valve (sometimes is not marked as tank) that way when it closes it relieves the pressure from the membrane, so only your sediment and pre carbon are under pressure, the membrane and di are not. But if the asov. Fails to close then the entire system is pressurized and with no way to push RO water the membrane will fail prematurely.

 

[jmc1974]

That's high enough to wear out your shower and faucet valves and cause everything to constantly drip.

Yes it is, I will adding a pressure regulator in the line coming to the house, but I had heard that all this neighborhood has had even their irrigation system leak underground.

 

[amnesiac]

Ok, let me try to help here... as plain as I can;

In order for the auto shut off valve to work correctly, you need a bladder tank, so the pressure from the water stored on the tank can help close the diagram. If you only close the valve after the last filter (carbon or di) it wouldn't be able to get it close. Not enough back pressure. As the bladder can build equal pressure as the source.

Use a tank even if you have a storage bin with a float, the float alone won't stop the RO from continuing to send water to the drain. Also this is a reason why RO membranes go bad so quickly, most should last 3-5years and more, but when not properly installed they get damaged.

FYI: I've been working in water filtration for the last 12 years and I'm WQA certified.

Wow, I never wouldve thought to do this. Sure enough it worked. Problem solved. Thanks so much for taking the time to post. I owe you one :dance: