RO/DI Unit Losing Pressure

[TheLadyCrash]

I have a 6 Stage RO/DI unit from BRS that I've been using for around 4 months or so. Normally my pressure when using it is around 80 PSI.

The last time I went to use it, I noticed that the pressure would drop from around 80 PSI to 30 PSI after I finished flushing the system and flipped the valve on the bypass back to normal flow. BRS told me I needed to replace my filters so I replaced the sediment filter and both carbon blocks. I am still seeing the same issue though with the pressure dropping as soon as I turn the valve on to run normal flow through.

Anyone have any ideas?

 

[Crabs McJones]

Does it stay at 30 PSI or does it slowly raise back up to 80?

 

[TheLadyCrash]

Stays at 30 PSI

 

[TheLadyCrash]

I should also mention that the water coming into the unit is at 12 TDS. Line 2 (so from the filters to the resin) reads 0 as does the line out, Line 3.

 

[Crabs McJones]

So how do you get it back up to 80 psi the next time You go to use it?

 

[Scott.h]

I would have to think you have something blocking a line internally that's lodged.

Do you feel the flush valve is working properly? Mine goes from 62 psi to 38 psi when I flip the valve. So I'm wondering if that valve is messing up too.

 

[TheLadyCrash]

I would have to think you have something blocking a line internally that's lodged.

Do you feel the flush valve is working properly? Mine goes from 62 psi to 38 psi when I flip the valve. So I'm wondering if that valve is messing up too.

Hmm...both of those could definitely be a possibility. Looks like I may be dismantling half this thing tonight to see if I can find a blockage somewhere. I think I may also have a spare valve somewhere I can try swapping out.

 

[TheLadyCrash]

So how do you get it back up to 80 psi the next time You go to use it?

If the valve is in the flush position, it's always showing 80 psi on the gauge. I can literally open and close it and I'll see the gauge jump back and forth between 80 and 30. Up until about a week ago, it didn't matter what position, always had 80 psi of pressure. So weird.

 

[blitz49]

Maybe the gauge is defective. Install another gauge if you have one to test.

 

[TheLadyCrash]

Maybe the gauge is defective. Install another gauge if you have one to test.

I don't think it's the gauge because water production has slowed to a drip - but thanks for the idea!

 

[blitz49]

I don't think it's the gauge because water production has slowed to a drip - but thanks for the idea!

Troubleshoot by disconnecting the hose between the 3 filters and RO membrane to check water flow. If water if flowing fine, than disconnect the hose between RO membrane and DI. Your membrane might be defective or clogged.

 

[TMB]

What you're describing seems exactly backwards from normal operation. It would be normal for the pressure to drop to ~30psi with the flush valve open - and return to 80psi when closed. If you can watch the out flow of the waste water line, you should see it increase flow while the flush is open, and the product water will slow. The reverse should happen when the flush valve is closed. Also, one way to check the flow of the pre-filters is to do the above test with them in the line. If the flow increases as expected they are flowing properly - if the flow never changes they could be part of the issue.

 

[Buckeye Hydro]

TMB is on the money - Sounds like you've confused what is open and what is closed on the flush valve. 30 psi means he valve is open. 80 psi means it is closed.

Russ

 

[Scott.h]

TMB is on the money - Sounds like you've confused what is open and what is closed on the flush valve. 30 psi means he valve is open. 80 psi means it is closed.

Russ

Yeah I thought that yesterday too. If that was the case I'd hate to see the water bill.

 

[Buckeye Hydro]

When you open a flush valve, you're providing a way for the concentrate ("waste water") to bypass the flow restrictor. Because the flow restrictor is bypassed, nearly all the flow and all the pressure shoots right our the waste water tube - that's why the gauge pressure drops. When you close the valve, nearly all that flow out the waste water tube stops, and pressure builds inside the RO membrane housing. This pressure is what forces water to pass through the RO membrane.

You can apply this same understanding to the flow restrictors themselves:
A "tighter" flow restrictor = less concentrate flow = higher pressure @ the membrane
A "looser" flow restrictor = more concentrate flow = lower pressure @ the membrane

Russ

 

[PatW]

I have the same system. My pressure is about 65. When I use the flush, it drops to 45. You may be mixing up the two. Also your 12 tds past your RO membrane sounds high. My tap water is about 130 tds. During flush, it gets to a minimum of 6 tds. After flush, the tds after the RO membrane runs at 2 tds. Unless you have really high tds in your tap water, I would think that your post RO membrane tds should be far less than 12 tds.

You could be confusing flush with normal operation. You could have a defective valve. You could have a plug somewhere. Or you might be due replacement of your RO membrane. I would rule out the other options before I replaced the RO membrane.

Also, you seem to get a gradual pressure loss. When I set my unit to flush, the pressure loss is immediate. When I shift to normal RO, the pressure immediately increases. So I am not sure what is going on.

 

[TheLadyCrash]

Soooo....as much as I HATE to admit this, yes...my dumb butt got them mixed up. I don't have any idea how that happened and I feel like a total n00b.

My guess is somewhere between changing the filters out and the rehanging the unit, I physically turned the tubing from the gauge/bypass around 180 degrees and confused myself. Yes, I also realize now there is a giant arrow and a label stating "Flow" right by the valve.

I'm gonna go drink a bottle of wine and pretend this never happened.

Thank you all for helping correct a silly mistake!!

 

[TMB]

Well... if you offered to share the wine all would be forgiven!!
Glad we could help though.

 

[reynaldoramon]

Just found this thread. So when I go from my valve being closed to open (flushing) my pressure goes up about 10 units. That is opposite of what it should be right. When I open it, I do see an increase in waste line output like I should. Also, I still get "filtered" water. Shouldnt that decrease? Wondering if my float valve is defective. I should say that my pressure gauge is immediately pre ro membrane.

 

[Buckeye Hydro]

When you open your flush valve, the gauge pressure should drop waaaaaay down - to something like 10 psi. At that very low pressure you'll get no more than an occasional drip out the product water line. But if you are still providing pressure to the membrane, then sure, you'll still get production.

You might want to give us a call when you are in front of your system. Something doesn't sound right.

Russ