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Unread 04/14/2017, 07:26 PM   #1
jpitch
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How far can water travel to your RODI filter?

I'm wondering what kind of head pressure comes from your main line? Can I run 30ft of tubing to my RODI with no issues?


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Unread 04/14/2017, 08:21 PM   #2
BlueRoofTang
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30ft of elevation, or just 30 feet of tube horizontally?


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Unread 04/14/2017, 08:42 PM   #3
Redman88
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Running a larger diameter tubing most of the way then the last foot or so going down to 1/4" is the best way to maintain pressure.


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Unread 04/14/2017, 08:50 PM   #4
uncleof6
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Quote:
Originally Posted by Redman88 View Post
Running a larger diameter tubing most of the way then the last foot or so going down to 1/4" is the best way to maintain pressure.
Pressure remains constant in a piping (tubing) system, as does flow rate. Pressure (and consequently flow rate) depends on the smallest diameter in the piping system. The larger pipe to smaller pipe is irrelevant. Only the velocity changes with pipe diameter. How far you can move water depends on the pump, and the smallest pipe diameter.


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Unread 04/15/2017, 12:17 PM   #5
Vinny Kreyling
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Hicksville had 55 PSI -- Miller Place has 78-80 PSI
Only way to tell is with a gauge on the line, or the one on the RO.


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Unread 04/15/2017, 12:21 PM   #6
jpitch
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I was never concerned running my line approximately 10ft to my rodi but now I'm running about 30ft with about 5ft vertical. There's not pump involved. I'm just tapping a main water pipe. I was just c


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Unread 04/15/2017, 12:21 PM   #7
jpitch
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I was just concerned about the longer distance to my rodi


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Unread 04/15/2017, 12:47 PM   #8
Vinny Kreyling
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Pressure should stay the same.


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Unread 04/15/2017, 01:27 PM   #9
woodnaquanut
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Quote:
Originally Posted by Vinny Kreyling View Post
Pressure should stay the same.
I agree.

Since flow is so low (GPD not GPH or GPM) there should be a very small/no pressure drop.

Don't you have a pressure gage on the RO/DI unit? Nothing like empirical evidence.


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Unread 04/16/2017, 05:58 PM   #10
Salty Waffles
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I called to ask BRS about this very question.

Their answer was no. The extra length of tubing won't affect performance from what they said.

The same holds true for the waste water plumbing. In my case I need to run it about 40'. They said, "No problem!". I asked if it would be worthwhile to go up to 3/8" tubing on either the supply or waste lines given the long run. They didn't seem to think the larger tubing would affect performance much.

Either way, I'm plumbing mine with 3/8". I like overkill.


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Unread 04/16/2017, 09:59 PM   #11
ca1ore
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FWIW, I ran my RODI system off long feed and discharge 1/4" tubing for many years. Never seemed to affect performance at all.


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Unread 04/17/2017, 06:16 AM   #12
n2585722
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Quote:
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FWIW, I ran my RODI system off long feed and discharge 1/4" tubing for many years. Never seemed to affect performance at all.
+1 here. I have done the same. No need for larger than 1/4". In fact I use 1/4" for my ATO and auto water change lines. Those are well over 30ft. I use peristaltic pumps for this so the flow in not high. I ran the tubing through PVC conduit so they are not exposed in the walls or attic. I also insulated the conduit in the attic. It does get below freezing here occasionally.


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Unread 04/17/2017, 07:45 AM   #13
jpitch
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Awesome. Thanks, everyone. My concerns have been addressed.


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Unread 04/17/2017, 09:16 AM   #14
ca1ore
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Originally Posted by n2585722 View Post
I ran the tubing through PVC conduit so they are not exposed in the walls or attic. I also insulated the conduit in the attic. It does get below freezing here occasionally.
Very smart. I do the same for anything running through an attic space - certainly for temperature but also mice of which I have many.


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Unread 04/17/2017, 10:25 AM   #15
mcgyvr
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If you go with 3/8" all the way you can/will see less of a pressure loss vs 1/4" all the way.


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Unread 04/17/2017, 12:57 PM   #16
ReefsandGeeks
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A bit late, but I have an identical situation, running 35 ft of 1/4 inch line to my RODI and it did not affect the performance in the slightest. Go as long as you need!


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Unread 04/18/2017, 09:47 AM   #17
jewlz
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Quote:
Originally Posted by uncleof6 View Post
Pressure remains constant in a piping (tubing) system, as does flow rate. Pressure (and consequently flow rate) depends on the smallest diameter in the piping system. The larger pipe to smaller pipe is irrelevant. Only the velocity changes with pipe diameter. How far you can move water depends on the pump, and the smallest pipe diameter.
While you're right that if the system is not flowing, the static pressure will be the same, I have to disagree with you on the diameter. Friction losses scale with the of velocity of the flow, so if you reduce the diameter of the pipe, you drive the flow velocity up, and this will certainly cause a head loss.

This is why you have to solve plumbing problems iteratively. See what the velocity is, then check the losses, calculate a new velocity, repeat until it converges.


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Unread 04/18/2017, 12:41 PM   #18
n2585722
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Quote:
Originally Posted by jewlz View Post
While you're right that if the system is not flowing, the static pressure will be the same, I have to disagree with you on the diameter. Friction losses scale with the of velocity of the flow, so if you reduce the diameter of the pipe, you drive the flow velocity up, and this will certainly cause a head loss.

This is why you have to solve plumbing problems iteratively. See what the velocity is, then check the losses, calculate a new velocity, repeat until it converges.
Most home RODI units do not have enought flow to cause this issue in 1/4" tubing. If it were a higher flow rate then there might be an issue with the pressure.


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Unread 04/18/2017, 03:15 PM   #19
jewlz
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That's probably true.


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Unread 04/18/2017, 06:01 PM   #20
Opcn
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Tiny difference. A long run of narrow tubing adds drag to the water, which creates a pressure gradient. The further down the tube the lower the pressure.

However, the speed of the water impacts the magnitude of the drag and the speed of the water is very low for an RO system. If it ran fine on 10' it'll run fine with an extra 20' and 5' of head. You won't even notice the tiny difference unless you have a pretty big RO unit.


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Unread 04/20/2017, 07:53 AM   #21
ReefsandGeeks
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I was interested to see how much pressure loss there was over the 30 foot line I have while the RODI was running. I hooked up calibrated precision pressure gages at both sides of the 30 feet of ro tubing and took measurments as the RODI was running (100GPD for reference). There was a 1.5 psi drop over the 30 feet of tubing at normal RODI flow rates. With this in mind, you can reasonably assume that for every 20 feet of 1/4" hose you use, you will lose 1 psi of pressure, Plus any head losses due to increases in elevation between the hose inlet and outlet.

This is a simple test anyone with 2 gages can perform, or if you only have 1, you can just plumb it in at the RODI inlet and see what the supply pressure is while it's running.


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Unread 04/21/2017, 05:01 PM   #22
billdogg
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I read somewhere that your ro/di HAS to be hooked up no farther than 1 mile from the nearest water tower. Any farther than that and you have to dig a well.















j/k



^^^What they've all said^^^


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