Auto Shut-off for RO/DI - which do I need?

[vanceny]

There are 2 options that I have found on the web. Which do I need?

Just the float switch
http://www.marinedepot.com/md_viewI...dproduct=KM1675

or this one:

Float switch and Solenoid
http://www.marinedepot.com/md_viewI...dproduct=KM1651

I just want to be able to stop the flow from my ro/di unit to my reservoir. The only real difference that I can see is the solenoid. Is that needed? Will just a float switch be enough to shutdown the ro/di unit? I already have a automatic shut-off valve.

Thanks all.

 

[bad coffee]

hooking up your RODI to a float switch that's connected to your top off container is REALLY bad for the RO membrane. If you're only dosing a couple of cups at at time, and the RO is filling up every time you dose, its bad.

Every on-off cycle shortens the life of the membrane. If you have a large resivoir, I'd let it almost completely empty before turning the filter on again.

 

[vanceny]

That's just what I'm doing. I plan on putting it on my resevoir when I'm making water so I don't need to keep an eye on it. I'm using a 30gal Brute trash can. Start it in the evening and hopefully by morning it will be done. I just dont want it to overflow while I'm asleep.

I guess the thread title is incorrect - it should read: auto shut-off - which do I need?

 

[Deanos]

I guess the thread title is incorrect - it should read: auto shut-off - which do I need?

Title edited.

 

[Buckeye Field Supply]

There are 2 options that I have found on the web. Which do I need?
Just the float switch
http://www.marinedepot.com/md_viewI...dproduct=KM1675
or this one:
Float switch and Solenoid
http://www.marinedepot.com/md_viewI...dproduct=KM1651

I just want to be able to stop the flow from my ro/di unit to my reservoir. The only real difference that I can see is the solenoid. Is that needed? Will just a float switch be enough to shutdown the ro/di unit? I already have a automatic shut-off valve.

If you already have an auto shut off switch, then you already have a pressure sensitive selenoid. So all you'll need os a float valve.

 

[Buckeye Field Supply]

hooking up your RODI to a float switch that's connected to your top off container is REALLY bad for the RO membrane. If you're only dosing a couple of cups at at time, and the RO is filling up every time you dose, its bad.

Every on-off cycle shortens the life of the membrane. If you have a large resivoir, I'd let it almost completely empty before turning the filter on again.

In this kind of configuration I have two primary concerns - neither of which is the life of the membrane:
1. If you run your system to a float in your sump, think about what could happen if the float valve fails. The DI water will flow, under pressure, and flow, and flow, and flow. If you happen not to be home for the weekend, guess what happens to the salinity level in your tank...

2. There is a phenomenon called "tds creep." You may have heard of it already. When your RO/DI first kicks on, it will send a flush of ?dirty? water to your sump. This is the water that has been setting inside the system while it was off. This high tds flow will only last for a few minutes. So if you have your system set up like you describe, every time the float drops just a tad, the RO will kick on for a very short period until the float shuts off flow again. In this way all you may every get supplied to your sump is high tds water.

A better configuration would have your RO/DI coming on much less often ? each time for a longer duration.

Russ @ BFS

 

[andylee]

After flooding my kitchen and ruining the ceiling and carpeting in the basement underneath, I got a new RO system with a float switch that I keep in the basement near the tank. The RO system already has an automatic shut off and it works fine. I don't know about membrane life, but the thing works perfectly. I don't think you're planning to plumb directly to your tank or sump, right? Just into a container for storage. Short answer: just the float switch.

I don't see what the problems Russ mentions have to with how the water is turned off.

 

[Buckeye Field Supply]

Andy - you're right. I think I misread one of the posts above.

My post was a vote against plumbing the di output right to the sump and using a float valve to control it. Sounds like Van Man is running it to an unpressurized container that he would fill up in one fell swoop - that's a good way to do it.

Russ @ BFS

 

[andylee]

Take a look at my post:tongue1:

http://www.manhattanreefs.com/forum...967-life-without-float-switch.html#post199974

Andy

 

[regal]

I use a float switch with a electrical solenoid valve from my RO/DI to the sump.

I connect the solenoid valve to the float switch. The float switch is connected to a timer so it only turns on for an hour a day to give me enough water for top off. If the float switch gets stuck, the sump will only get 1 gallon of water per day instead of 25 GPD.

 

[FRY]

regel that is the best way of doing it no floods

 

[Pedro]

I use the kent auto shutoff kit and it works perfect. As soon as the float in the reservoir fills up it shuts the unit off. This has saved me of some major floods.

 

[vanceny]

Thanks for all the responses. Looks like both options will work for me its just a matter of how much protection I want. And yes this will only be used to fill a unpressurized container. (brute trash can)
On another note concerning the tds creep, how long should I let the water run before I let it fill my container? Do I just need to flush it or let it run through the di as well? I make water probably every few days, if that makes any difference.

Thanks to all.

 

[Buckeye Field Supply]

Let it run for a couple of minutes to avoid the higher tds water prduced at start up. If you have a means to bypass the DI cartridge during ts period, that would be a good thing - and would extend the life of your resin.

 

[vanceny]

Thank you. So I will just flush the unit and bypass the di cartridge. Is there any concern over the water that's left in the di cartridge?

 

[Pedro]

I used to think about the water that was left in the containers whether it will be stagnant or not. The last time i ran the unit i tested the initial water and it measured 0 on my tds meter. So now i don't bother draining the initial water. Although it's probably a good idea if you are concerned!

 

[vanceny]

I haven't been draining it. But how often are you making water? I guess the longer the period in between the more problems it can have.