RODI

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Getting a flow restrictor that give you the flow you need shouldn't be a complicated thing. We're here if you want to get that resolved.

 

[JoshH]

Hi Russ,
You folks tried to help me on two occasions with no success so I see no reason to go for three and waste your time. The last time we spoke I replaced the membrane housing on the chance it may have a hairline crack. I reseated the membrane, we talked about pressure and temperature. In the end the only thing that works is to replace the membrane to save on DI and that gets to be about a toss up in cost. I was surprised that I tried two different capillary restrictors and neither one worked any better than my regulary 550 inline restrictor. I guess the good news is that I only use about 75 gallons of RODI per month

If you don't mind me asking, you used a capillary flow restrictor correct? Did you cut them to the right length to allow for a 1:4 product to waste ratio?

 

[jtl]

If you don't mind me asking, you used a capillary flow restrictor correct? Did you cut them to the right length to allow for a 1:4 product to waste ratio?

I did not change the length of the restrictor because it was sized for a 75 gpd membrane but you bring up a good point. Maybe I should trim a little off to increase the flow although it is pretty short as it is.

 

[Buckeye Hydro Verified Sponsor]

Is the "75 gpd capillary flow restictor" blue?

 

[jtl]

Is the "75 gpd capillary flow restictor" blue?

Yes, I had it in my box of spare parts but it had never been used.

 

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Looked at your pic above - the tube connected to the wye, just UPSTREAM of the flush valve - it doesn't look like that is connected to your concentrate port.

 

[jtl]

Looked at your pic above - the tube connected to the wye, just UPSTREAM of the flush valve - it doesn't look like that is connected to your concentrate port.

Wouldn't that be something if I had this on wrong after looking several times at diagrams online when I set it up. Anyway. There are two ports coming out of the membrane housing. One is centered and one is off set. I have the drain connected to the one that is offset and the water going to the DI coming out of the center one.

 

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That is correct. Here's a pic that helps show this:

 

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Are you certain there is only ONE flow restrictor installed anywhere in the waste water tube?

 

[jtl]

Are you certain there is only ONE flow restrictor installed anywhere in the waste water tube?

Certain, I just double checked.

 

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So you went from a 550 restrictor, to a 735 restrictor (blue 75 gpd restrictor), and you are getting LESS waste?

 

[jtl]

So you went from a 550 restrictor, to a 735 restrictor (blue 75 gpd restrictor), and you are getting LESS waste?

That is correct, strange as it is.

 

[Buckeye Hydro Verified Sponsor]

Then something is wrong. Does the capillary tube on the blue restrictor have a kink in it? Is the capillary tube partially blocked with scale?

If both restrictors are functioning properly, and if all other variables are held constant, there is no way for a 735 restrictor to have less flow than a 550 restrictor.

 

[jtl]

Then something is wrong. Does the capillary tube on the blue restrictor have a kink in it? Is the capillary tube partially blocked with scale?

If both restrictors are functioning properly, and if all other variables are held constant, there is no way for a 735 restrictor to have less flow than a 550 restrictor.

I actually have two blue ones and they were both brand new in the package. They are not a lot worse than the 550 but close, certainly not any better. The 550 is about 1.25:1 and the 735 is closer to 1:1.

 

[Buckeye Hydro Verified Sponsor]

That's not possible given what you've told me, so something else is happening/going on. The blue ones allow MORE flow to drain - they are less restrictive. Maybe you want to try a 100 gpd restrictor.

 

[jtl]

I believe you, it defies logic. What if I trimmed the capillary tube back?

 

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Nothing to be lost - go fo it. If the tail is already pretty short, not likely to make much difference

 

[jtl]

So today I had some time and trimmed the capillary tube. No noticeable change. Than I got to thinking that maybe the problem is the output of RODI not the waste. I have a 75 gpd membrane and when I measured the RODI water being produced it was 135 gpd. I recall this being the case a year ago and I replace the membrane and the enclosure since then. Just another piece of the puzzle.

 

[Buckeye Hydro Verified Sponsor]

Higher than expected permeate flow could be from a cracked RO membrane housing, a failed membrane, higher than spec temperature and pressure.

Is the TDS of that RO water bad?

 

[Buckeye Hydro Verified Sponsor]

Maybe you want to ship your RODI to us for diagnosis and repair?