RO/DI Back Pressure

Dwb859

Dwb859

New member
I just recently got a RO/DI unit installed and I have a question that I'm sure most anyone can answer lol

1. I'm using a ball value on my unit to make water. Once I turn the ball value off the canisters build pressure, which kits on the "full" light and then the system does a membrane flush. After that the DI canister still has water in it? Is this normal or how it's suppose to be. I guess with the valve being after the exit of the ro/di unit, the canister is gonna hold water in it?

2. Should I leave my water feed line on for good and the ball valve that exits the unit closed until I make water?
 
Just my oppinion but my ball valve is in line between the main supply and the filters, the way you have yours the pressure is always going to be in the system which could weaken the seals! Its ok to have water in the filters when the unit is not in use.
 
That makes sense. I changed it back to how it was to begin with. The vavle is on the feed line. What I'm not understanding is once I turn off the valve to stop making water. The full light never comes on and the unit doesn't do a flush (which is why I starting messing with things.) How can I get the "full" light to light up? I was told that back pressure causes it but the way my valve setting is I'm not getting back pressure from what I'm seeing. Once the valve is turned off, the water doesn't enter the unit.
 
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The directions I'm reading say....When product line is full (via float vave or external shut off valve) the unit will light up the "full" light and begin to flush the RO membraine. How will a ball valve on the product line do anything?
 
Here is a video of the unit I have. The main difference I see in the video is the valve that is installed on the product line afte the water leaves the unit. Once that is closed the unit builds pressure like it would from a float switch and shows the "full" light. Once this happens I shup off my feed water line. Does this sound right? The only reason I'm closing the feed line at the end is so water pressure doesn't stay in the unit. Does a silinoid prevent this? Pretty sure the unit has one.
http://www.youtube.com/watch?v=3OCimZQdceY
 
Dwb...,

I am not an expert in RO/DI, but I have my unit that I maintain for quite a while. IMHO it is OK to have a valve at the end of the system. It is like the faucet on the sink (don't forget this things have been invented first for drinking water). Your system should have an ASOV (automatic shut-off valve) that will protect when not in use. Seals will not see a pressure higher than feed line pressure. If I were you I will let the system pressurized to avoid trapping air. This way you will prohibit bacterial growth.

hope it helps,
MaLi
 
MaLi said:
Dwb...,

I am not an expert in RO/DI, but I have my unit that I maintain for quite a while. IMHO it is OK to have a valve at the end of the system. It is like the faucet on the sink (don't forget this things have been invented first for drinking water). Your system should have an ASOV (automatic shut-off valve) that will protect when not in use. Seals will not see a pressure higher than feed line pressure. If I were you I will let the system pressurized to avoid trapping air. This way you will prohibit bacterial growth.

hope it helps,
MaLi
Click to expand...

Your saying I should leave the valve closed at the end of the unit and leave the feed line valve open? I do want the unit full of water when it's not working? The unit has a high pressure switch which switchess off the water after it detects pressure.Thanks
 
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The membrane is supposed to be under pressure when off. By shutting off the input water you may be shortening the life of the unit.

The unit needs an ASOV. Does it have one? Auto shut off valve.

asov.jpg
 
I guess a high pressure switch is the same thing? It shuts off after 10 seconds of detecting back pressure?
 
Alright, I traced the lines and it seems like that's what the high pressure which does. I still have water pressure in the membrane but nothing coming out of the waste line. Even unpluggd the unit to see what happens to the pressure switch, nothing seem to change. Thanks for all the replies, very much appreciated.
 
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