Scored myself a free reverse osmosis

Not just any ro but one that does 720gpd. It had a problem where the unit would not stop sending water down the waste line. Instead of fixing it the customer just replaced it with a cheaper unit. The best parts are that the tds out of the current membranes is still good and they gave me 2 replacement membranes so I am set for atleast 6 years.

Chrisl77 said:

Not just any ro but one that does 720gpd. It had a problem where the unit would not stop sending water down the waste line. Instead of fixing it the customer just replaced it with a cheaper unit. The best parts are that the tds out of the current membranes is still good and they gave me 2 replacement membranes so I am set for atleast 6 years.

Click to expand...

The water going down the drain, while "normal", can be excessive, depending on your inlet water pressure. The other factor is that typically the ASV (automatic shut off valve) is installed backwards in the system to how it should be installed. My RO system was, and it NEVER shut off period. The proper piping is counterflow, and not concurrent flow. So when you reverse it, the valve can shut off against the pressure, and not with it. If your water pressure is high like mine coming in, it becomes critical.

Oddly, I had to "convince" the fools at the RO place that it needed to be repiped for future systems, so that people don't have these problems. Of course what do I care, and they want to argue instead of have a working system, and I am sure never changed their schematics.

Anyway, the real solution is to use a permeate pump in all these RO systems. The other thing while I am thinking about it is that going into the drain if you aren't going to use the permeate pump is a little plastic piece to control flow. If it ain't there, you ain't gonna control the flow.

Info on permeate pumps.

http://www.freshwatersystems.com/t-reverseosmosispermeatepump.aspx

Chrisl77 said:

Not just any ro but one that does 720gpd. It had a problem where the unit would not stop sending water down the waste line. Instead of fixing it the customer just replaced it with a cheaper unit. The best parts are that the tds out of the current membranes is still good and they gave me 2 replacement membranes so I am set for atleast 6 years.

Click to expand...

The water going down the drain, while "normal", can be excessive, depending on your inlet water pressure. The other factor is that typically the ASO (automatic shut off valve) is installed backwards in the system to how it should be installed. My RO system was, and it NEVER shut off period. The proper piping is counterflow, and not concurrent flow. So when you reverse it, the valve can shut off against the pressure, and not with it. If your water pressure is high like mine coming in, it becomes critical.

The diagram in the link below shows the countercurrent piping at the ASO.

Anyway, the real solution in terms of limiting water to drain, faster filling of expansion tank, and improvement in water quality as well is to use a permeate pump which is a $60 item.

http://www.freshwatersystems.com/t-reverseosmosispermeatepump.aspx

Also, see that flow restrictor in their diagram after the RO module(s)? You need one. If you don't have one, get one. And if you do have an expansion tank, be sure the pressure is actually 8-10 psi. You can pump the up with a bicycle pump.

I guess I should have posted what system it was. Its a Merlin on demand ro system. It works with 2 gigantic and expensive membranes to supply 720 gpd of continuous flow. I install them for a living and the diagnosis was that the manifold inside it went bad and needed to be replaced. For the cost of the parts and labor to repair it the customer decided to just replace it for a model that used a storage tank. The customer also had problems with this unit supplying water to her ice maker. If she did not have a set of replacement membranes that she offered to me for free I would have just tossed this thing in the trash but since I am only using it for brewing water I am not concerned with it not stopping running to drain.

Interesting. Yeah that's a lot of water I thought you might have had a misprint there. Well cool you scored!