RO unit question

dempseyjosh

dempseyjosh

Member
Do RO units stop sending water through them when their holding tank is full?
I have a kent unit and I have a 3gal holding tank for it. I never worried about this before, because I was living in an apartment complex and didn't have to pay for my water. But now that i'm in my own home and will have to pay for the water I don't want to waste a ton of it.
I thought that I have an auto shut off(a block that is after the ro membrane, before the line oging to the reserve tank) on it but it seems that there is always water coming out of the waste line, even when the holding tank is full.... or so I think it is..
 
acrylic51

acrylic51

Active Member
Thinking alittle more about what you said your ASOV(auto shut off valve) being after the membrane is correct. It's either built into the pressure vessel housing(canister which holds membrane) or it's a little white device inline after the membrane, but there has to be some sort of float device to apply back pressure to the ASOV to trigger it to shut off. Is it possible to disconnect the line from the holding tank and verify that water is coming out of the product line? Then you would need to be able to apply back pressure to the product line with either a float valve or a Johnny Quest shut off valve to verify the ASOV is properly working. It's not uncommon for them to stick or malfunction.
 
dempseyjosh

dempseyjosh

Member
now that i think about it more, i'm not sure i understand it. How is a float valve going to apply back pressure, it' just going to close up that line so water isn't exiting it any more, then the line would get full and it should shut off. When my tank is full and then the line becomes full, it should shut off, right?
also, now that i'm thinking about it at work, i'm probably picturing it wrong, but how is it being placed after the membrane ever going to stop the water coming from the waste line, which is the ultimate goal?
 
dempseyjosh

dempseyjosh

Member
"If you have a home RO with a pressure tank, you do not need a float for the system to be automatic"
i found this when looking for info about asov's. Maybe it is just stuck(can it be taken apart and rebuilt?), or i need to check and make sure it doesn't need to be on the other side of the membrane.
 
mrdc

mrdc

Active Member
And on a side note about waste water. I have my waste water going into other buckets that I use to water my plants and flowers.
 
acrylic51

acrylic51

Active Member
True the pressure tank would should apply the back pressure telling the ASOV to shot water flow off to the membrane. Obviously if your continually getting waste water your ASOV isn't functioning, but where is the excess good water going if holding tank is full?
 
dempseyjosh

dempseyjosh

Member
i think i figured it out. we'll see once i let it run for a little while.
I had a check valve just before the holding tank that would have prevented any back pressure. i got the instructions from the manufacturer and moved it to where it is supposed to be(after the membrane). and time will tell.
but with the check valve after the membrane, the solenoid is actually before the membrane, after the filters. but we'll see how things work out.
 
acrylic51

acrylic51

Active Member
Makes sense now.... I have seen a particular brand during a stint have an issue with their ASOV. Somtimes you have to give them 24hrs to function. Keep us posted
 
dempseyjosh

dempseyjosh

Member
well i figured it out. besides the check valve before the holding tank, i also had one before the ASOV that was preventing the back pressure as well!!! so i moved the one to where it was supposed to be and removed the other.
It really isn't that tough to understand.......once you actually try to understand it, but it is very easy to mess up if you aren't concentrating.
 
acrylic51

acrylic51

Active Member
I knew backpressure had to be applied to the ASOV to make it function properly. What was/ the purpose of the check valve?
 
dempseyjosh

dempseyjosh

Member
i don't remember how much of this was put together when i bought it, and how much i had to do myself. I do remember that it was a display item. So it could have been put on wrong by who ever assembled it for display, or i rushed through it when i bought it.
there was no purpose in the check valve, it is what was actually preventing the asov from working. the check valve didn't allow that back pressure to get to the asov, it stopped at the check valve.
The only spot it is supposed to have the check valve is where the water leaves the membrane, so that water doesn't go back into it.
 
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