RODI unit not pressurizing.

[Smprc]

I have a 5 stage BRS RODI unit with dual 75gpd membranes. The membranes are about 1.25 years old. I get about 7 TDS before the DI dual stage. I used to get about 4 TDS before the DI stage. One day the sound that the aquatec 8800 booster pump made sounded unusual and I noticed that the pressure gauge read about 64ish. I thought well this baby is done for, it gave valiant service for over 5 years and its just time to replace. No biggie, I replaced it and guess what...the pressure stayed the same, around 64ish. I remember the first time I hooked up the booster pump years ago and instantly saw the pressure jump to over 80. I was happy. But as I said, it no longer goes up. I disconnected the primary tube at the point of entering the RO membranes. When I tried to stop the flow with my thumb the pressure gauge shot up to over 80ish. I also notice that when I disconnected the feed to the DI units the pressure remained at 64ish.

I could use some trouble shooting advice from you all. At first I thought something is clogged, but wouldn't that increase pressure? In any case, not sure what to do.

 

[KrisReef]

I believe that when the RO membrane is getting old, clouged up maybe, that it can lower water pressure passing through. Maybe try removing the membrane and run the filter (briefly) to test if it's time to replace, or at least backflush?

 

[Smprc]

So I understand, you want me to remove both the RO membranes and run the unit, yes briefly to see if it pressurizes? And I do have an auto back flush that runs for a few minutes when the system starts up.

 

[KrisReef]

So I understand, you want me to remove both the RO membranes and run the unit, yes briefly to see if it pressurizes? And I do have an auto back flush that runs for a few minutes when the system starts up.

Yes, if the membrane is the source of pressure loss, removing it will not damage the unit but the pressure should rise if the unit is backed up.

My understanding on RO membranes is that they can only be backflushed some limited number of times until they need to be replaced.

I don't have a back flush, but I presume all the flow valves on your filter are properly aligned? This is the other source of common filter problems. :)

 

[vetteguy53081]

I have a 5 stage BRS RODI unit with dual 75gpd membranes. The membranes are about 1.25 years old. I get about 7 TDS before the DI dual stage. I used to get about 4 TDS before the DI stage. One day the sound that the aquatec 8800 booster pump made sounded unusual and I noticed that the pressure gauge read about 64ish. I thought well this baby is done for, it gave valiant service for over 5 years and its just time to replace. No biggie, I replaced it and guess what...the pressure stayed the same, around 64ish. I remember the first time I hooked up the booster pump years ago and instantly saw the pressure jump to over 80. I was happy. But as I said, it no longer goes up. I disconnected the primary tube at the point of entering the RO membranes. When I tried to stop the flow with my thumb the pressure gauge shot up to over 80ish. I also notice that when I disconnected the feed to the DI units the pressure remained at 64ish.

I could use some trouble shooting advice from you all. At first I thought something is clogged, but wouldn't that increase pressure? In any case, not sure what to do.

May be membrane or even the sediment filter cartridge which recently was my issue. No pressure and it looked very yellow ad I changed it and had flow, then changed the rest of cartridges

 

[Smprc]

I am still trouble shooting. KrisReef, I was about to remove the membranes when it occurred to me what if my flow restrictor isn't restricting anymore, so I pulled the waste line and used my thumb to restrict the water and instantly saw the pressure begin to go up. And then I thought that if I removed the membranes and the pressure didn't go up, that would indicate a problem with the flow restrictor anyways. Thoughts on my thought process?

 

[KrisReef]

I am still trouble shooting. KrisReef, I was about to remove the membranes when it occurred to me what if my flow restrictor isn't restricting anymore, so I pulled the waste line and used my thumb to restrict the water and instantly saw the pressure begin to go up. And then I thought that if I removed the membranes and the pressure didn't go up, that would indicate a problem with the flow restrictor anyways. Thoughts on my thought process?

I'm gonna leave you to this. You are on the correct path.

 

[Garf]

I am still trouble shooting. KrisReef, I was about to remove the membranes when it occurred to me what if my flow restrictor isn't restricting anymore, so I pulled the waste line and used my thumb to restrict the water and instantly saw the pressure begin to go up. And then I thought that if I removed the membranes and the pressure didn't go up, that would indicate a problem with the flow restrictor anyways. Thoughts on my thought process?

Have you got the restrictor bypassed? I don't think it's likely they just stop working.

 

[Smprc]

UPDATE....

So far its been an epic fail. I replaced the automatic flush valve...that did nothing.
So I then replace the RO automatic shut off...that did nothing.
I finally gave up and replaced the 2 RO membranes...STILL NOTHING!

At this point I should have just purchased a new unit.

To answer Garf's question...not to my knowledge. I have not made any adjustments other then replace parts in the exact same way.

Im open to trying one last time. Or do I just leave it as is.

 

[KrisReef]

I replaced my pressure gage once, the old one always read zero.

 

[Smprc]

I mean it could be reading wrong...however, when the system starts the automatic flush valve opens and I can see the pressure drop into the 20's and then the flush valve closes and the pressure rises to 66-68. Then when the system turns off the pressure rises again way passed the dials limit, I just checked and its past 100! Here is a 2 and half min video of me turning it on and off so you can see the pressure. Sorry for the bass...someone is watch something.

 

[KrisReef]

If it makes water, I would just use it and ignore the pressure gauge.

 

[Smprc]

I'm good with that...I was more concerned with the quality and of the amount that is produced. I just remember reading something long ago that RO membranes are most efficient if the pressure is in the 80s, but I could just be wrong and I'm worried over nothing. Nonetheless...thank you so much!

 

[Tangdora]

How is your water line before the pump hooked up. Are you using a saddle valve. Had a similar issue once turned out to be that. Ended up replacing it and cleaning out the hole it tapped. Not sure if mineral deposits stated to block it. But my issue went away after.

 

[UncommonSense]

Then when the system turns off the pressure rises again way passed the dials limit, I just checked and its past 100!

Red flag!!
Also, indication of the likely problem…

You haven’t messed with the booster pump’s pressure adjustment screw, or with the booster pump’s inline Automatic Shutoff (ASO) switch at all, have you?

 

[UncommonSense]

If it makes water, I would just use it and ignore the pressure gauge.

With all due respect; this isn’t the best advice…

Pressure gauges are typically something you want to maintain on one of these systems, particularly when using a booster pump!!

The pressure gauge tells you various things about both RO system, and booster pump performance!

— Not to mention catching a safety related issue in this particular case (max system operating pressure is 110PSI, IIRC)! Also, likely pointing us towards the real culprit of OP’s ongoing troubles!

 

[KrisReef]

With all due respect; this isn’t the best advice…

Pressure gauges are typically something you want to maintain on one of these systems, particularly when using a booster pump!!

The pressure gauge tells you various things about both RO system, and booster pump performance!

— Not to mention catching a safety related issue in this particular case (max system operating pressure is 110PSI, IIRC)! Also, likely pointing us towards the real culprit of OP’s ongoing troubles!

Good point. I take mine off line (zero pressure) when it's not making water (60psi for the OP, ~ 50 at my house.)

 

[foamboy]

When was the last time you replaced your carbon and sediment filters? If these are plugged up it’ll reduce the pressure available to the RO membranes. Another thing to check would be your flush valve. It’s cheap enough to replace and see if it let go and isn’t restricting enough flow on the waste side. Your pressure gauge is after carbon and before RO, so if the pump is working properly those are the only things that could be causing you problems. Unless of course you tds is way high on your production water after RO, then it would be a problem with your RO membrane itself.
Afterwards watching your video, I revert back to my first question. The pressure didn’t come from nowhere, the pump produced it and only then made it through your sediment and carbon to your pressure gauge.