RO Unit Shutting Off Due To Low H2O psi

[Red Baron]

After adding my 2nd IBA my RO unit shuts down with the Low Pressure light coming on when both bays are in use at the same time. I have 2" water line coming out of the soft water system then it reduces to 3/4". This morning I had a 2" T installed so that the 3/4" line could run directly to the charcoal tank rather than around the ER, hopefully freeing up the flow enough to solve the issue - it didn't help.

Slightly closing the ball valves that feed the rinse tanks helps, but I get very close to the water level getting below the low water cutoff when doing that. One thought is to discard the Jobe floats in the rinse tanks in favor of Robert Bobs so that the floats can be set higher, allowing the rinse tanks to fill up more...allowing the ball valves supplying water to the rinse tanks to be closed some more and thus reducing water flow demand from the main line and holding the water psi higher.

I have new freer flowing membranes on the way, which will help, but of course that addresses a symptom not the problem.

I feel like I'm chasing my tail. Ideas?

 

[I.B. Washincars]

Can you feed both autos out of a common tank so only one fill valve will come on? Of course, the tank would have to be larger, but this may be your opportunity to capture your reject and use it too.

 

[MEP001]

Is there an adjustment for the pressure switch on the RO? I assume that the system shuts down and doesn't come back on without being reset, otherwise it wouldn't be much of a problem. Would adding a large bladder tank to just the RO supply be feasible?

 

[Red Baron]

Can you feed both autos out of a common tank so only one fill valve will come on? Of course, the tank would have to be larger, but this may be your opportunity to capture your reject and use it too.

I have a reject reuse setup which used to use to feed the rinse tank, just as you suggestd. However, the new D&S pump stand setups come with a system that uses the reject for high pressure wash function and it goes directly from the reject tank to the Cat pumps.

 

[Red Baron]

Is there an adjustment for the pressure switch on the RO? I assume that the system shuts down and doesn't come back on without being reset, otherwise it wouldn't be much of a problem. Would adding a large bladder tank to just the RO supply be feasible?

I found out the RO system has an automatic reset jumper, which I activated. The problem is it shuts off for 5 minutes the first time, 15 the second, then 60. By that time I'm running out of RO on a busy day. I guess the new high flow membranes will help with that. Also, I assumed that the automatic reset was an emergency type function and shouldn't be used regularly as part of normal operation - am I wrong about that?

You're right, the RC manufacturer suggested a bladder might help. When you say large, how large? 10 gal? Where would you install a bladder?

 

[MEP001]

The high-flow membranes will help you fill the tank faster, but it may make the problem worse since you'll be drawing even more water from a source that's already reduced in pressure for some reason.

At what pressure does the system shut down? It would be safe to allow it to go right down to zero, as long as the pump isn't creating a vacuum on the plumbing.

A twin-membrane system with 4 x 40 membranes is going to use at least 8 GPM. I would suggest at least a 20 gallon bladder tank (you only get half the total volume of the tank as usable pressurized water). You'd want to add a check valve to the RO supply and put the tank somewhere between the check valve and the RO unit. Without a check valve, that stored water will just flow back into the rest of the plumbing.

If the system rejects more than 1:1, it's fairly simple to replumb it to do so. That will cut down on the demand for water and will usually improve the volume of the product.

Before you do add anything, have you looked for a cause for the low pressure condition? Put gauges on your backflow preventer (before and after) to make sure it isn't failing and causing a restriction. If it's a reduced pressure zone unit, it should act like a regulator but not cause a greater drop in pressure with increased flow. Open the softener bypass with both autos and the RO system running and see if your line pressure maintains better than with it in service. The resin degrades over time, faster if the water has high levels of chlorine, and as it breaks down the flow is reduced.

 

[madscientist]

Red,

I've learned as you are learning, that RO machines require a precarious balance of pressures and flows to keep them running properly. Even when things are set properly you can have an occasional drop in city water pressure which throws everything off again. I had that happen this weekend and I felt like one of those guys that plays seventeen instruments simultaneously, using all my limbs and appendages to adjust everything at the same time hoping to keep the machine from cutting off. I think you have the right idea by closing your ball valves on the rinse tanks. Making those tanks hold more will also help, as you plan on doing by switching float valves. I think your free flowing membranes will actually cause your RO machine to have lower pressure, as opposed to newer, "tighter" membranes that increase pressure. Check to see if your RO water output is correct. My 40 inch membranes put out 1.25 gpm (I think). If the amount you are putting out exceeds the max output of your membranes, you might have a blown membrane. You could still have relatively spot free water if you have one blown membrane and one or two good ones, but your pressure will be lower if a membrane isn't "tight".

You can install a booster pump right before your RO machine with a pressure switch that makes it kick on only when needed (all places drawing water running at once). I've had good success with Teel pumps for this purpose, but I think those models have been discontinued. I'm sure there are others that will work.

Also, does your RO machine have a reject and a recirculate valve? By cutting down the amount that is rejected or recirculated you force more through the membranes, creating higher presssure. Adjusting those valves may be all you need to do to find the perfect balance that your machine requires.

 

[mac]

I thinkMEP has the best answer so far. Rather than add things like a pressure tank and pump check the simple things. It may be, in fact should be, possible to modify the timimg function on the low pressure shutoff/reset. Checking the backflow preventer is also a good idea. They are made of steel and corrode over time. Youy may also be able to add a gate valve to the output side of the production pump, which would not allow the pump to go into low mode. I think you are wasting your money on the socalled high flow membranes. If yours are still making good water, return them.

 

[I.B. Washincars]

I have a reject reuse setup which used to use to feed the rinse tank, just as you suggestd. However, the new D&S pump stand setups come with a system that uses the reject for high pressure wash function and it goes directly from the reject tank to the Cat pumps.

Can you not just feed both autos from that reject tank and not use the original rinse tanks at all? Years ago I fed an old Mark VII like that, with a large poly tank. I could have easily fed a 2nd auto out of it with just another outlet in the tank.

 

[BayWatch]

The one thing I've learned about new plumbing is it is full of junk and when you first turn the system "on', trash will collect in everything. Have you checked/changed the "monthly" filter? If i recall, you just opened that IBA. If your system is like mine the filter is before the pressure switch. I have seen systems where the filter hadnt been changed in a while, which lowered the gpm and pressure. A quick swap fixed it and your water is the same as mine. The charcoal could have also clogged the filter on initial start up.

 

[soapy]

I have a Culligan RO unit that did similar shutdowns when I first installed it. It does not have a auto reset so you had to manually turn it back on after low water pressure sensor would shut it down. I tried a few things and finally I took a 3/4 inch nut and put it under the low pressure switch so it could not shut down the Ro unit during low water pressure times. That was 11 years ago and I have not had one problem with it since and everything still works fine.
Another thing I did was to install a hydrominder on top of the RO tank and feed the hydrominder with soft water. On a very busy day when the Ro water gets close to running out the hydrominder will let the RO tank fill with soft water so I can keep running. I have never had a complaint about water spots on cars. At other locations when I have had to use soft water only while the RO unit was down for repair I have never had a complaint either.

 

[Red Baron]

Still having problems. How do I identify and disable the low pressure switch?

 

[BayWatch]

What type of unit? Some are built into the lines, others have a poly tube from a line to the switch. Once you find the switch, you should be able to jumper the wires.

 

[MEP001]

There will be something electrical connected to the plumbing before the pump at some point. It may be a tubing line going back to the controller, but it's usually a switch of some type on a "T" fitting with wires that go to the controller.

Can you upload some pics of the unit?

 

[Red Baron]

There will be something electrical connected to the plumbing before the pump at some point. It may be a tubing line going back to the controller, but it's usually a switch of some type on a "T" fitting with wires that go to the controller.

Can you upload some pics of the unit?

Site would not let me upload photos. They are here: http://www.facebook.com/photos.php?id=1263740436#/album.php?aid=47167&id=1263740436

Not great quality; my camera didn'ty want to focus in the cold. Photo 3 is inside the control box - a "Nason" gadget with 3 prongs and 2 of them connected to wires going to the motherboard. A larger wire goes to what I'm sure is the pressure switch seen in photo 2. Can I simply unpluf the 2 wires going to the Nason gadget?

 

[MEP001]

You'll probably have to jumper the circuit closed, but it won't take long to find out. As soon as you unplug it, it will either continue to run or quit for a low-pressure fault. Jumper them if it does the latter.

Did you ever check the inlet water pressure when it shuts off? You don't want to bypass the switch with it dropping to zero PSI, you'll need to fix the pressure issue one way or another, or you'll end up with more, bigger problems.