RO/DI setups

[daplatapus]

First off, let me describe my RO/DI system then I'll pose a couple questions. Bear with me, I know this post is going to be lengthy.

I have a "The Filter Guys" OCEAN REEF MISER SIX STAGE RO/DI 100 GPD RO/DI system with an added booster pump.
Water comes into my booster pump, through the 3 pre-filters, then 2 RO membranes, then through a pressure switch which controls the booster pump, then into my 2 DI cartridges, and finally through the float valve in my Brute tub.

The Problem: With this system, my wastewater never stops running. Which is normally not that big a deal. I store roughly 25 or so gallons of water, so I only make water a couple times a month. That's when I go down, turn the water on to the system, turn the booster pump on, and wait for it all to fill up. Once the Brute can is full, the float valve closes, creates back pressure which turns off the pump. BUT... the waste water keeps flowing. So I have to remember to go down and shut everything off. Something which I have forgotten a few times until the next day. So I'm looking at finally fixing this system.

I have been under the assumption that it really isn't all that good for the pump to come on for a few minutes a few times a day. Although I'm beginning to wonder if that's not such a big deal. I mean, systems used solely for drinking water under sinks do that all the time. What I must admit, is I don't like the sound of that booster pump coming on in the middle of the night as it tops up my Brute.

It has been pointed out to me what I am missing in my system is an Automatic Shut Off Valve and a check valve in the permeate tube between the membrane and the shutoff valve.

After talking to a guy at Aquasafe is Sydney yesterday, I'm not sure if this will work either, unless I have a pressure storage tank. My understanding of this whole system being truly automatic is the check valve and ASV (auto shut off valve) rely on the back pressure created by a pressure tank. While the float valve in my Brute will create some pressure, as soon as a few millimetres of water is used by my ATO, the system would come on. While if I had a pressure tank, my understanding is I could use up several gallons of water before the system replenished itself. Depending, of course, on the size of the pressure tank.

So, I guess here's my questions:

1) Does any of this make sense or have I got fundamental flaws in my understanding of how these systems work?

2) If I DO have this all straight, why are we using 30 gallon Brute cans to store FW for ATO? My system, for example, probably uses up 3-5 gallons a day in evaporation. If I had even a 4 gallon pressure tank reservoir or even 2 in tandem (for a total of 8 gallons of FW), that would more than likely suffice for my day to day top off.

3) If all the above is correct so far, is it possible to allow a Tunze osmolator to operate a solenoid valve instead of a water pump that would open, allowing water to drain from the pressure tank into the sump when the infrared eye deems necessary?

[mark]

found when mine would keep running fault was with the check valve.

Diagram showing check valve and asv without pressure tank. Output to Brute, use ATO as normal (drawing from Brute)

[hillegom]

Maybe this will help:
electrical connections"
http://www.watergeneral.com/support/pdf/ELEC_DIA2.pdf

And here is the piping without an auto shut off. (ASOV).
Sounds to me like your ASOV is malfunctioning and needs to be replaced. Just try setting up your system like this:
http://www.watergeneral.com/support/...struction2.pdf

And I do not own any shares in this business, just use their technical support, although I have bought from them, hassle free

[daplatapus]

Originally Posted by hillegom

Sounds to me like your ASOV is malfunctioning and needs to be replaced.

I don't have one to begin with, thus part of my problem

But from what I've been told by Aquasafe, the ASOV won't work without back pressure. A pressure tank will still provide that pressure even though you use a gallon or two, while just a float valve on Brute can will only provide back pressure until the first time your ATO fires up and drains the teeniest bit of water out.

[hillegom]

I don't have a booster pump, so am not familiar with it. But that second link I sent you has the schematic for a booster pump without an ASOV like you probably have set up. Is your el wiring as in the first link? and your plumbing set up as in the second link?

[mike31154]

Can't help with your question #3, but this thread does appear to explain why my ASOV never turned off the waste water flow! I don't have a pressure tank on my system either. Thanks!

I removed my ASOV some time ago & for my set up it was a good thing. Less pressure drop between the sediment/carbon stages & the RO membrane, which should help output performance. I don't miss the ASOV at all since I never let the system run unattended. Too many minor floods & potentially worse floods for me to trust Auto anything when it comes to water production.

I monitor water pressure with 2 gauges & TDS with 2 dual TDS meters. House pressure is good, no need for a booster pump. With an incoming TDS in the 170 range (except on the rare occasion the city switches me to the Duteau Creek water source), it's best for me not to run the system in short "top off" type bursts. It takes a good 2-4 minutes after opening the source water valve for the RO output to drop down to 1. On initial start the RO output TDS is pretty close to source water TDS (over 100) for at least half a minute. This would really do a number on my DI media, so the first half gallon of RO water goes into a waste bucket, then I make about 5 gallons of RO water before I even think about sending anything through my DI stage.

This has worked very well for me, may not work for everyone, especially those with less time on their hands to keep an eye on things. May also be unnecessary for folks with very low source TDS, say 10 or less, like you lucky folks in most of the greater Vancouver area.

[hillegom]

I have looked at the second link again, the one with the plumbing connections.
Seems you need to install that check valve. Make sure that its in line properly, not reversed. It needs to be able to flow towards the RO membrane.

If water is constantly flowing into your drain, even when the RO water is shut off, as at that time when the float valve shuts the ro off, Then the only shut off you have left that is supposed to be working is the electrical solenoid. This should be shutting off the incoming water.
Because you do not have a check valve installed, the system will not hold pressure and the solenoid will never think that enough ro water is made. So the solenoid will reopen and the pump will turn on trying to make more ro water. But the float valve is closed, so everything will go to the drain. The flow restrictor will allow water to flow slowly to the drain, finally releasing pressure in the system and the whole operation will repeat
Install the check valve would be what I would do

[daplatapus]

Hillegom:
I don't have an electronic solenoid valve on my water supply, just a manual one. That would certainly work to shut everything off and would really make an ASOV redundant.

Lol, well now I'm feeling just a bit sheepish. I totally forgot I ordered an ASOV and check valve from Ray and it just showed up. So I went downstairs to hook it all up and upon closer inspection (a lot closer) there is a ASOV hiding way in behind my dual membrane that I never saw there before. But there isn't a check valve. So I inserted it and now my waste water does stop (albeit after about 3-5 min) once the pressure rises enough to cut out the booster pump.

So I guess that at least helps to shut it off if I forget to turn the system off.

[mark]

The pressure tank is not needed.

In the diagram I put up, follow the flow. The back pressure across the asov is created when the float valve (connected to output of di) in your brute is closed forcing the diaphram in the asov downward to shutoff flow coming from the third stage. The check valve is required so the asov doesn't reopen due flow in waste line removing pressure. The source of the pressure is from the supply (even with pump off).

[daplatapus]

Yeah, that's right. With it set up that way, my RO/DI system will kick in every time the ATO pump does and draws a bit of water out of the Brute. I guess now I am wondering if a pressure tank or two would supply say 2 or 3 cycles of my ATO before my RO/DI system turns on, thus prolonging the run time through the membranes to avoid what Mike was describing in his post.
That might have been why, in my brain, I thought 1 long cycle of the RO/DI was better than many quick cycles that this set I now have gives me.


... and then again, maybe I'm totally overthinking the whole thing, lol