BRS RO/DI Pressure

Hey guys, I just got my new 4 stage RO/DI unit from BRS. I have it flushing right now and everything is working perfectly, only issue is my water pressure. Its at about 32psi right now...which is way under the 50psi the unit calls for. How imperative is it that I get the booster pump? Id like to hold off a few weeks if I can...right now the RO/DI shows TDI coming in at 127ppm and out at 0ppm, so it is working...but how long will it work under these conditions? I only need to make about 15 gallons a week at the most.

Thanks!

 

I had the same issue with my unit (low pressure) also. I think the most important issue is that your getting a 4 to 1 ratio between your waste water (black tubing) and your clean (blue tubing) water. Since your not dealing with making a large amount of water, you should be ok for now. However, Its my understanding that low pressure is more taxing on your filters and membrane, which will result in your having to purchase the membrane and filters more frequently. I did eventually purchase a booster pump and my psi went from an average of 42 psi to 92 psi instantly. I'm sure one of the RO/DI guru's will chime in soon with a more informative explanation. Good luck.

 

40 psi is about the bare minimum for a membrane to operate even poorly. The graphs drop off the page at about 35 psi so they are not working at all.

I am confused with your TDS readings. I can only assume you have the dual inline TDS meter at this point but it should be plumbed so it reads the RO only TDS and the RO/DI TDS. If that is the case then 127 is very high and proves out what I am saying, it should be 98% less than your tap water TDS, whatever that is.
If I am wrong and you have a handheld TDS meter then you need to test the tap water TDS, RO only TDS and the final RO/DI TDS all three to troubleshoot your system.

One thing I will caution you about and maybe they did not include it in the directions, ALWAYS flush your RO membrane seperately before installing the DI cartridge or you are prematurely wearing out your DI resins with the antimicrobial treatments being flushed out of the RO membrane. If you are not flushed yet, remove the DI and flush 3 to 5 gallons to waste before installing it again.

Do you live in a single family home and possibly have a pressure regulator on your incoming line that can be adjusted up? Regulators are installed on a lot of new homes to meet plumbing codes but are often turned down way too low.
If not a booster pump may be in your future. You can find them on sale at the bottom of the page here:
SpectraPure Customer Appreciation SALE! 20% - 50% off

Make sure when you are comparing prices they include the correct power supply as most do not and you end up paying more.

 

Thanks for the advice fellas. Ill look into adjusting the house pressure...I rent so I gotta be careful. The TDS readings are 127 tap water going in to the unit (red line) and 0 coming out of the unit (blue line).

 

If thats with a dual inline TDS meter then it is installed incorrectly. It should be reading the RO only (IN) and RO/DI (OUT) with the two probes. The tap water TDS is not much use except to check occasionally to calculate the Rejection rate of the membrane. You do need the RO only TDS though as it tells you when the membrane is going bad and gives you an ideea how long DI resin should last. Move the IN probe to the line between the membrane housing and the DI canister.

If its with a handheld, which i prefer, then you need to disconnect the line from the RO membrane down to the DI canister and pull a RO only sample to see how well it is performing, another way is to remove the DI cartridge temporarily and test the RO output from tha tpoint.

 

Ok, Ill move the in probe and report back. The out is in the correct place Im assuming? So it is functioning, right? Thanks for your help.

 

Alright, update. The in reading is now .003, the out is still .000. Can I make it 2 weeks till I can get a booster? Or should I just buy DI water from the store for now?

 

We know the DI is functioning but we don't know about the RO membrane, the DI could be doing much of the work which is common at low pressures.
Since you have such low pressure you should probably measure your waste ratio too. Take a measuring cup and a clock or watch and time the treated flow for exactly one minute then do the same with the waste flow. Let us know how much you get out of each. Something that may help the situation would be a capillary tube flow restrictor trimmed for a proper waste ratio. Your tap TDS is pretty low at 127, you could get by with a 3.5:1 or even 3:1 waste ratio nad probably pick up some pressure.
As a quick test you can kink the waste line a bit or temporarily install a 1/4" ball valve on it and slow the waste for a minute to see if the pressure gauge rises. Often in colder waters and/or lower pressures the waste is too high further lowering the system efficiency. See how much your pressure rises when you temporarily restrict or stop the waste flow.

 

A TDS of 3 out of the RO membrane means you are just under 98% rejection rate or removal efficiency which is good.
127-3=124, 124/127=.976, .9763x100=97.63% rejection rate.
Your DI should last quite awhile at 3 TDS going in but would be much better at 80-90 psi, probably last 2-3 times longer per cartridge.

 

k, The waste water production for one minute was about 360-375ml. For the good water it was about 100ml. When I cut off the waste water line it had a minimal effect on pressure, rose maybe 1-2psi but nothing significant. Thanks again for your help, Id be lost without it!