Need help with RO solenoid shut-off

Delphinus · #1 07-09-2003, 05:16 PM

I have rearranged my topup for my tanks into a single reservoid auto-fed by the RO unit. Problem is the reservoir is now 30 feet "downstream" of the RO unit (I used 1/4" line) and now the shut-off doesn't seem to shut the RO unit off when the reservoir is filled.

It works fine when the output line is about 6'-8' or so. So I'm guessing that what's happening is the pressure takes a LOT longer to buildup in a 30' section of line over a 8' section of line (the solenoid works off pressure .. the pressure builds in the output line once the float valve is shut, the pressure moves the solenoid and shuts off the intake to the RO.)

So here's the question. Does my theory seem reasonable? (I had contemplated using 3/8" line instead of 1/4" because I was worried the line was too long, but if my theory is correct, the 1/4" is still better because the 3/8" line will take even longer to build up enough pressure to shut off the RO).

StirCrazy · #2 07-09-2003, 11:24 PM

Tony can you move the RO closer to the reservoir? it might be that because of the lenght the signal to shut it down is to weak to actually stop the supply. I am assuming you are using a pressure shut off here in conjunction with a float valve. If not let me know what you are using.

Steve

Delphinus · #3 07-10-2003, 02:28 PM

That is what I'm using. Unfortunately moving the unit itself isn't really an appealing option because where it is, is convenient for having the unit close to a source and close to a drain. I'd have to run two lines instead of one.

I adjusted my float valve so it shuts off at a lower level, it just seems to require a little more time for the pressure to build up sufficiently. I gave it a shot last night and it seems to be working. Gonna watch it for a day or two before I really decide if it's working.

ldzielak · #4 07-15-2003, 09:24 PM

Tony,

Water is not compressible and the pressure should be same no mater how long you lines are. I can't imagine you have enough air in the RO water to cause any spring effect that would cause a long delay. If the pressure is not high enough to shut off the solenoid, then you have a leak. The 1/4" line could also be flexing, but I have always had long lines, first installation was 20 feet, now I have 40 feet. No problems.

Lee

Delphinus · #5 07-15-2003, 10:30 PM

Yeah, water isn't compressible but I'm pretty sure that given enough pressure, pex can bulge a little bit (kind of like a really long thin water balloon), so I was thinking that maybe the pex line was doing some of that. More line == more surface area .. etc. etc. blah blah blah. (I work for a pipeline automation company remember?

Oh right, you Metso guys sold us off, we were making too much money or something and it was making the rest of the company look bad. J/K!!

)

Anyways the shutoff part works fine now (there is a lag though between float valve shutoff and solenoid shutoff) but now the really annoying thing is that the solenoid reopens about every 5 minutes for about 30 seconds or so and every time it happens it sounds like someone having really bad gas ("EeeeeeEEEEEyyyuurrrrrrRRRRp!!!!!!" That wasn't me, that was my RO unit. Honest!

) .... and you can hear it throughout the entire house. I've tried adjusting the throttle a bit but it doesn't really change anything except for the frequency.

I don't know... I have about 30-40' of 1/4" pex and maybe that is an inappropriate tubing to use for this application? Should I think about stepping it up to 3/8" or something? I don't really see how the increased diameter would really help with this phenomenon, though, now I'm starting to run out of ideas.

For now I just turn the unit off if it gets too annoying, which seems to work OK so long as I remember to eventually turn it back on (the reservoir servicing two tanks is only 20g, but the powerhead pressuring the tank lines sits about halfways up the reservoir (I hope to eventually make this a sort of kalk reservoir) and it doesn't take more than a day and a half or so to replace 10-15g of evap from the two tanks).

ldzielak · #6 07-16-2003, 12:05 AM

So sad to hear you miss Metso!!! I'm prety sure my little division will be up next for sale net, since we are also have a new idea about making money, not spending it uselessly, but don't get me started....

I can't see how making the line bigger would make the problem better, I would think it would just get worse. I can't hear mine at all. Maybe you solenoid needs a cleaning? Just a guess.

You could also install a secondary solenoid, electric on a timer, so it is only on for 1 hour a day, or enough time to make noise and fill your container.

Lee

StirCrazy · #7 07-16-2003, 02:13 AM

Actualy making the line 3/8th or 1/2" might do the trick.. the way thoes work the back pressure from the output sends a signal back to the unit which uses that pressure to pinch off the supply. so if you have a very long tube you will have compressability from the air in your water. also there is some give in plastic lines and when you are talking about a long run this adds up.. so what you have happening is the unit shuts the water off then as the water settles and compresses and the pex releaxes the pressure drops which allows your valve to flutter..

I still say the best way to stop it is to move your RO closer to the float valve. Also when yuo use a float valve it is going to flutter a bit as they are slow opening and not "ON" or "OFF" like.

Steve

Delphinus · #8 07-16-2003, 05:34 AM

Well ... maybe my next house I can have the tank area closer to the water source & drain.

Maybe I'll try the larger tubing for now if I feel really ambitious.

Frankly I'm a little disturbed just how much water is flowing into my tanks. The evaporation rate is insane. If it would be a little slower then at least it would be a little better.

Quote:

You could also install a secondary solenoid, electric on a timer, so it is only on for 1 hour a day, or enough time to make noise and fill your container.

Hey don't laugh I have been considering that. Just a garden hose type valve, they're not that expensive and I can just set the unit to be on when I'm not home.

Good luck with your spinoff/selloff thing. Hopefully you can at least end up at a company whose name people can actually spell, or at least not have an embarrassingly long email address. When I tell people the "@telvent.abengoa.com" domain they're like ... "A Ben .. what?" .. Yeah. Great, laugh it up (I really like how all the email headers are in Spanish. When people send me email and it bounces the message is like .."Los Sientos, no routo del hosto. Server siesta... Hasta Manana!!!")

Canadian Man · #9 07-16-2003, 07:28 AM

Quote:

Originally Posted by Delphinus

Good luck with your spinoff/selloff thing. Hopefully you can at least end up at a company whose name people can actually spell, or at least not have an embarrassingly long email address. When I tell people the "@telvent.abengoa.com" domain they're like ... "A Ben .. what?" .. Yeah. Great, laugh it up (I really like how all the email headers are in Spanish. When people send me email and it bounces the message is like .."Los Sientos, no routo del hosto. Server siesta... Hasta Manana!!!")

You make me laugh Tony!

Buccaneer · #10 07-16-2003, 08:05 AM

Quote:

Originally Posted by Delphinus

When people send me email and it bounces the message is like .."Los Sientos, no routo del hosto. Server siesta... Hasta Manana!!!")

I will have to ask my Mexican friend to translate that for me

LOL ... you need to quit that job and go on the comedian circuit

Think of all the reef shops you could visit on the road and send us back some really cool frags

Cheers