Ro/di question

[jbdreefs]

I'm slowly but surely putting together a water mixing station. I'm considering using a float valve to run the ro/di water tube to the container. When the valve closes, does the waste water shut down too? I do not want to have to manually turn the ro/di unit on and off. My concern is that the waste water will continually flow. Any help is appreciated. I don't fully understand how the ro/di unit works...other than knowing that when i turn it on, I get good water out of the blue line

 

[shafiq_hossain]

Most, if not all, of the RODI units I've seen come where the waste water will automatically turn off.

 

[eagle9252]

<p style="text-align:left"><span style="color: black"><span style="font-family: Verdana">This is what you need. I did not know about these when I built mine system. They cost more when purchased alone. When pressure builds up from when the float shuts off it is to cut the flow of water off to the RO/DI unit. </span></span>



<p style="text-align:left"><span style="color: black"><span style="font-family: Verdana">I personally don’t like this. And here is the reason. I don’t want to always keep my RO/DI unit full. I want to let the water have a turn over or be used up. Instead I installed a manual timer. I use about 3/4g a day and I can get about 1 gal an hour. So I just turn my timer on for 90 mins. I have a float in the container and it will shut off and not over flow. I don’t fill it up all the way so I don’t have to worry about running the unit after tank is full. </span></span>



<p style="text-align:left"><span style="color: black"><span style="font-family: Verdana">Also if you will add a second membrane to the waste line it will increase you output of good water and reduce your waste water. </span></span>

<p style="text-align:left">you can order it cheaper and pay shipping or pick it up local and pay more but it washes out if you have the time to drive to go get it.


http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/auto-shut-off-kit-for-reverse-osmosis-systems.html">http://www.bulkreefsupply.com/store/products/reverse-osmosis-filters-and-systems/ro-di-accessories/auto-shut-off-kit-for-reverse-osmosis-systems.html</a>

[IMG]http://www.bulkreefsupply.com/store/media/catalog/product/cache/1/image/5e06319eda06f020e43594a9c230972d/a/u/auto-shut-off-kit.jpg alt="" />

 

[buckeye field supply]

JBDreefs;752647 wrote: I'm slowly but surely putting together a water mixing station. I'm considering using a float valve to run the ro/di water tube to the container. When the valve closes, does the waste water shut down too? I do not want to have to manually turn the ro/di unit on and off. My concern is that the waste water will continually flow. Any help is appreciated. I don't fully understand how the ro/di unit works...other than knowing that when i turn it on, I get good water out of the blue line

If your system has an "AUTOMATIC SHUT OFF VALVE" then when the float valve closes the ASOV will stop the flow of waste water. Here are two ASOV's so you know what to look for:

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Russ

Edit:

eagle9252;752688 wrote: <p style="text-align:left;"><span style="color: black;"><span style="font-family: Verdana;">

Also if you will add a second membrane to the waste line it will increase you output of good water and reduce your waste water. </span></span>

​

First - remember that what folks call "waste water" really would be better thought of as "flush water" in that this water serves the important purpose of internally flushing the surface of the semipermeable membrane to keep the membrane from fouling/scaling.

When you configure a system with two membranes in series (the waste from the first membrane going to the "in" port on the second membrane), for this discussion let's say it's two 75 gpd membranes, the system behaves like you have a single long (75 gpd x 2) 150 gpd membrane.

Now - if you use a proper flow restrictor, that is, one for a 150 gpd membrane, you'll have about a 4:1 waste to product ratio. Sounds familiar, right?

If however you don't change the flow restrictor - meaning you keep using the same restrictor you were using when you just had one 75 gpd membrane, then you'll see a waste to product ratio much lower than 4:1. But remember that the recommendation for a ~4:1 ratio comes from the membrane manufacturer. They are telling you that you need about a 4:1 ratio to keep the membrane flushed and keep the membrane from fouling or building up scale. Run the system with a lower ratio and you will foul/scale the membrane(s) quicker than would have otherwise been the case.

Instead of adding a second membrane to lower that ratio, you could have just changed out your flow restrictor ($4) instead. A much less expensive approach to get you to the same endpoint in terms of saving on waste water.

Now, to confuse things just a bit. Filmtec specs call for the 4 to 1 ratio on the basis of assumptions about the water that will be supplied to the membrane. If you have very soft water you MAY be able to get a decent service life from the membrane running at a ratio lower than 4 to 1 (e.g., 3 to 1). Remember that the waste water from the first membrane is about 25% harder than your tap water.

Bottom line: If what you are after is reduced waste water, experiment with a different flow restrictor for $4 instead of messing around with a second membrane plumbed in series.

As a side note, you can also lower the ratio by increasing the pressure delivered to the membrane (with a booster pump), because flow restrictors are sized assuming you are providing factory spec conditions (50 psi and 77 degrees for Filmtec membranes). Increase the pressure and you'll drive more water through the membrane and viola - less waste water. But as I mentioned above, if you do this (just like over-restricting a membrane) - the lower the waste to product ratio, the shorter the lifespan on the membrane.

Makes sense?

Russ​

 

[grouper therapy]

Perfect sense!! Will a needle valve suffice for a flow restrictor?

 

[buckeye field supply]

You can do that, but its not very practical on the types of systems used in this hobby. I'd rather see you use a capillary tube restrictor.

Russ

 

[grouper therapy]

Buckeye Field Supply;760599 wrote: You can do that, but its not very practical on the types of systems used in this hobby. I'd rather see you use a capillary tube restrictor.

Russ

Thanks for the reply . May I ask why?

 

[buckeye field supply]

Sure - a few reasons:
-They don't require constant adjustment like the needle valves do.
-They are inexpensive so its no big deal to have one for the winter and one for the summer (each season comes with its own water temperatures in most parts of the country)
-They can be "adjusted" with the swipe of a razor blade.
-They won't tempt you to shut off they waste flow too much as people temd to do with adjustable restrictors.

Russ

 

[spankdog]

I just installed the BRS shut off kit and it works great. No more flooding my laundry room.

 

[grouper therapy]

Buckeye Field Supply;760608 wrote: Sure - a few reasons:
-They don't require constant adjustment like the needle valves do.
-They are inexpensive so its no big deal to have one for the winter and one for the summer (each season comes with its own water temperatures in most parts of the country)
-They can be "adjusted" with the swipe of a razor blade.
-They won't tempt you to shut off they waste flow too much as people temd to do with adjustable restrictors.

Russ

sounds reasonable thank you for the info.

 

[fdr_dippin]

I have a GE system that was handed down and I am using for the first time (new filters installed). I was unpleasantly surprised at how much waste water that was created. I guessed about 3:1 and now I'm reading 4:1 is common. The waste water flows while the product water trickles in my setup. I Plan to run the waste water outside the garage to water the flower beds or something. I'll try running with the feed water valve wide open to see if I create less waste. I don't like waste.

 

[buckeye field supply]

FDR_Dippin;760825 wrote: I have a GE system that was handed down and I am using for the first time (new filters installed). I was unpleasantly surprised at how much waste water that was created. I guessed about 3:1 and now I'm reading 4:1 is common. The waste water flows while the product water trickles in my setup. I Plan to run the waste water outside the garage to water the flower beds or something. I'll try running with the feed water valve wide open to see if I create less waste. I don't like waste.

Yes - by all means open the feed water line wide open. You want as much pressure as you can get to a max of 80 psi. Lower pressures will yield relatively more waste and less purified water.

Russ