help with ro/di unit

[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 ermeate 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