help with ro/di unit

[watson0720]

i just recently purchased a used ro/di unit from a guy local to me cus i was getting tired of hauling water back and forth from the store. well for some reason it doesn't seem to produce any water but makes a ton of waste water, i took it completely apart to see if i could locate the problem. water seems to flow good through the three main chambers, and through the auto shut-off valve, but once it reaches the ro membrane nothing comes throught the product side but pours out of the waste side. so i am pretty sure the ro membrane is toast. is there anyone out there that can help me and walk me through this thing, i can tear it apart and put it back together a million times but that doesn't fix anything. help please.

[betiuminside]

I am not an expert, but I know you will recieve help soon, but I will suggest to post pictures.model,brand etc.
Good luck

[safeuerwehr]

call bryan at H2O.....he can talk you through the proper flow pattern....his number is on the sponser forum....good luck

alfred

[betiuminside]

Alfred is right... also... you could order a new membrane or filters and he will help you a lot.

GL

[watson0720]

Soumi Knight Systems is the company that makes the system, i can't find anything on them except maybe just an ebay online store, i have emailed them and will give dan a call tomorrow and hope that helps, teaches me a lesson, quit buying stuff you know nothing about. i thought 40 bucks what a deal but i see now by the time i buy new filters and hopefully get it running i could have bought a new one.

[betiuminside]

well I think it was a good deal... but when you buy a used system, you HAVE TO change the filters... no matter what...

Was the unit up and working when you bought it?

[watson0720]

yes it what it was running like it is now, and i really don't think the guy knew what he was doing which leads me to believe that i am sure he was tearing it apart either, i think you are right it is time for new filters, cus the design is simple water goes in here and come out here thats it.

[Tubbs]

hello, i have the same Soumi DI unit as the guy you bought it from...i removed the DI unit...and it has worked fine....the water is supposed to be about 90%pure w/o DI ...so it was good for my application... i was 120$ on ebay so you did indeed get a hella deal....FYI....used aquatic parts never work as they did new...

[Instar]

There is supposed to be a restictor on the waste outlet that effectively puts pressure on the membrane. That's what makes an RO membrane work. If the guy had a flush kit attached and then removed the flush bypass when he sold it to you, he may have removed the restrictor as well. You will have to get that part and a diagram from the manufacturer or get their flush kit and replace what he removed. New pre and high quality carbon block filters are a must so you can keep track of how much water has gone through them and know when to change them. If chlorine or chloramines get to the membrane, that will ruin it. The RO membrane is the most expensive part to replace. Although the flow is much less through the RO side, both the waste and the good water side of an RO unit should flow within a minute of turning on the water in a non-commercial application. If you have a float valve on the RO (good water) side, then it has to be open in order to work. The membrane may also be damaged in the case of an old used unit if it has dried out too much from lack of use and if he drained the unit and had it sitting for a long time without seals. If it was sealed or plugged to preserve the membrane, remove the seal and then hook it up. Do not remove restictors, washers or O-rings in the process. Once you get it to flow, check the TDS after it has made at least 10 gallons of good water and without the DI cartridge to see where you are. Once your TDS is way down low, it is safe to install a new DI cartridge. Most good units normally will produce less than a 20 TDS before the DI cartridge.

[GaryP]

I think Instar is right. I have never seen an RO membrane fail with it not making any water. It is does fail its because the carbon cartride was exhausted and allowed chlorine to sneak through and destroy the membrane. This causes it to make more water, not less.

Try disconnecting the waste water tubing from the RO membrane and see if there is a restrictor in there.

[watson0720]

there is a brass needle valve on the ro membrane unit itself, but doesn't seem to change a thing either open full or closed

[Instar]

That sounds like either a built in flush valve or a former access port for either an ohm meter or pressure gauge with it just plugged using that valve. Definitely get on the internet and see about instructions with diagram for that as well as a restrictor. If the restrictor is supposed to be a valve too, that is really a total pain to get right for optimal pressure without a pressure gauge on the membrane. If he removed all the reusable things like valves and gauges before selling the unit, you will have to replace those parts and adjust them correctly, if thats what is needed, in order to find out what kind of water quality you can get out of it. You won't know if the membrane is shot until you do all that.

[safeuerwehr]

Pics?

[BuckeyeHydro]

The advice above seems pretty good. To troubleshoot the system, we need a little information. For you to get that information, you'll need a way to assess your water pressure at the membrane (i.e., a pressure gauge), and the tds at three locations (1. tap water; 2. the purified water from the membrane before it goes into the DI (a.k.a. the permeate); and 3. after the DI. To measure the tds you'll need a tds meter.

When was the last time the prefilters (sediment filter and carbon filter(s)) were changed?

Does the brass fitting look like a needle valve on the waste line? If so - you don't need the pressure gauge to adjust it. Screw the needle valve in until you have a 4:1 waste :permeate ratio. If you screw the needle valve all the way in and you get no waste water and no permeate, then you either have very low water pressure (unlikely - but you'd need a pressure gauge to verify), or your membrane is damaged.

When people buy used systems it is not uncommon that they buy a damaged membrane. Was the unit unused for a period of time before you bought it?

Russ @ BFS