Which configuration will move more water?

GuySmilie

Premium Member
I'll be the first to admit that when it comes to fluid dynamics, I am one lost soul.
I'm thinking on how to plumb my new OR3500 return pump and have a few ideas, but do not have a clear grasp of the outcome. For simplicity sake, let's assume that both pumps shown here are OR3500's and are rated at 1000g/h @ 0' head. All plumbing is 1" PVC in a vertical column configuration with open terminations at the ends.

pump_plumbing.jpg


OK, I've have a pretty clear understanding on how Pump A will perform
when it comes to flow rate and volume of water moved.

But how will Pump B perform, compared to Pump A?
Any constructive input is most appreciated.
 
the only way you can reduce the loss is to increase the diameter of the pipe.. 1" is probably just about the diameter where the friction reduction kinda drops off, thats why i guessed pump a..

pump b is really jsut introudcing friction increasing bends.. so its not more efficient that a single larger stright pipe
 
You have added 3 addition elbows and the feet of vertical pipe is practically double so it is going to be pretty significant difference.

When I plug into the head loss calculator I get 5.53 feet for A and 10.75 for B. So if you have a flow curve for that pump then see what the flow rate estimates would be.

I have always heard you want to T or Y off at the last possible moment not at the beginning.
 
<a href=showthread.php?s=&postid=9868411#post9868411 target=_blank>Originally posted</a> by David Grigor

......I have always heard you want to T or Y off at the last possible moment not at the beginning.
OK - so if I were to modify the scenario to include a third configuration,
you're saying that the flow rate and volume delivered would be better with PUMP C.

Anyone else agree or disagree with this?

pump_plumbing_rev1.jpg
 
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david, exactly what are you entering into the calculator to get those numbers, and what pump is it..

im pretty sure that calculator can not replicate the scenario here.. it definately doesnt count as twice the height..

guy, i would say that b anc c are going to give pretty similar results.. if you wend with b, and used 1.5" for the t and elbows, then reduce to 1" or 1.25" to go up, i think that would really minimize your losses.. as for c (and a), either do it exactly as shown (its not that that bad for flow) or do it with 1.25" up to and including the tee and elbows...
 
<a href=showthread.php?s=&postid=9868411#post9868411 target=_blank>Originally posted</a> by David Grigor
You have added 3 addition elbows and the feet of vertical pipe is practically double so it is going to be pretty significant difference.

When I plug into the head loss calculator I get 5.53 feet for A and 10.75 for B. So if you have a flow curve for that pump then see what the flow rate estimates would be.

I have always heard you want to T or Y off at the last possible moment not at the beginning.

Thats completely untrue. People need to stop posting in these threads when they dont even have a basic understanding of mechanics.


Setup B will move significantly more water because there will be much less friction head. He's essentially doubled the area of his return pipe. Yes, the elbows add a little more head, but that is more than alleviated by running twice as much pipe.


B will also outperform C by a large margin. Because the pipe is split earlier, the velocity in the majority of the pipe is lower, so theres less losses to friction.
 
im not sure if b's friction-head would definately be signifigantly greater than c's lower friction-head (from diameter) plus the tee's and elbow's friction-head.. plus the disruption of flow in the beginning of c where the tee is hurts b/c b is using that length to develop laminar flow..

though it certainly could be (im not saying your wrong)..
it does depend on the pump, and 1" is considered pretty well suited for 1000gph so its friction-head may be very little compared to its gravity-head.. so IF the head from the elbows and tees is greater than the drop in friction head from b to c.. b would be better

if you really wanted to know for sure you would have to do the math.. pretty simple but you would need a curve for the pump.. or find a better calculator..
 
"and 1" is considered pretty well suited for 1000gph so its friction-head may be very little compared to its gravity-head."

That I really disagree with. Loss is significant with 1" pipe and 1000gph, especially when discussing low pressure pumps such as these.
 
if you use the head loss calculator for a pcx30.. different but 1000gph.. i dont know if that one is on the list.. i dont really knnow what pump it is

so these are pcx30, 1" pipe

4 feet of height = .41 feet of head loss

0 feet of height just 2 90's = .55 feet of head loss

could mean nothing its just a calc.. but..
 
right, but we can't consider it 2 90s.

Consider this, if the line came up off the pump, immediately turned left, and then turned up, we'd have two 90s. If we changed that first 90 to a T, it would be less backpressure. Example B puts significantly less backpressure on the pump than just putting two 90s on the pump.
 
GuySmilie: I am not sure about the math either but I used a Eheim 1260 and when I set up for a test run I liked the B setup over the A setup. I thought it looked like more flow and besides that now new clean water comes into the tank at both end of the tank. I do not have mine finished yet so it was not glue or anything. Also remember not to use the sump as your means of water flow but I am sure you already knew that. Good luck as I think your system is moving along faster then mine.
 
yea i realized it at the time, but was thinking it may not make a huge diference so i didnt note it, but yea those numbers are completely insignifigant.. the calculator would have the water going through each elbow at 2x the rate we want to calc the loss at making it all wrong..

but guy (assuming your tank isnt like 700 gallons).. maybe you should consider running much less gph through the sump 1 - 1.5x (refer to umm another thread.. i forget the name, it deals with this exact issue someone will know..)..

its just not necessary... you're paying for head loss just for circulation.. if you just do a few hundred through the sump and some dc powerheads or whatever you'll be saving on elec....
 
Rich_1833:
No, the OR3500 will mainly serve to return water to the main tank, with water movement within the tank a secondary effect. For major internal water movement I will be using other devices, if needed.

As for the comments on me using Pump A, it is shown only for comparison purposes. I will not be using Configuration A.

I am surprised that some of the other notable pump guru's have not chimed in yet; the usual suspects....hahn, bean, DesertRat, etc. Come on guys, don't hold back now! :D
 
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How do you plain to return it into the tank? As in do you plain to use bulkheads or just go over the backside.
 
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