Drain Pipe Sizing

[milkman55]

I have one question on the drain. I am draining from two 1 inch corner overflows on a 120 gal display into the sump which is in the basement. I keep from cutting too many holes in the floor, can both 1 inch dranins wye into a 1 1/2" single drain to the sump without reducing the flow?

On my return, I was going to run a 1 inch pipe back up through the floor and then wye off to two 3/4 inch loc lines again up through the corner overflows.

Any thoughts?

 

[fishnub]

imo 2 1" drains will need a 2" pipe just to be safe.

 

[billdogg]

i would go with the 2" as well - should be quieter/less likely to back up one or the other

 

[tydtran]

It seems like a 1.5 in. pipe should work. Your 2 1in. drain pipes have a cross-section area of 1.57 sq. in. , your 1.5 inch pipe will have a slightly bigger cross section of 1.77 sq. in.

 

[horkn]

A single 2" pipe will outflow two 1" pipes.

I suggest using the 2" to keep it safe. It will probably be quieter with larger pipe than needed.

 

[milkman55]

Thanks for all the suggestions. Any reason not to use Sch 26 PVC for the drains instead of the heavier Sch 40 since there is no pressure on the drain. I got the idea from the Durso website that suggested the Durso be made from Sch 26 because it would allow the water to drain faster than Sch 40?

I realize the return is under pressure and needs Sch 40.

 

[Srixon]

Bigger is better.....just my personal opinion.

 

[horkn]

For the durso, yeah use sch26 if you have it.

 

[Seths Dad]

A 1" line will drain 600 gph, 1.5" 1200 gph, 2" 2100 gph. Check out the calculators on the home page, great tools.

 

[Hammsreefbeer]

<a href=showthread.php?s=&postid=15741542#post15741542 target=_blank>Originally posted</a> by horkn
For the durso, yeah use sch26 if you have it.

your avatar is the best.. :lol:

 

[horkn]

It is classic.

 

[d0ughb0y]

<a href=showthread.php?s=&postid=15741863#post15741863 target=_blank>Originally posted</a> by Seths Dad
A 1" line will drain 600 gph, 1.5" 1200 gph, 2" 2100 gph. Check out the calculators on the home page, great tools.

going along the same line

http://flexpvc.com/WaterFlowBasedOnPipeSize.shtml

for gravity flow
1" = 960 gph
1.5" = 2100 gph

more than sufficient to use 1.5", and actually, using a 2" will probably cause more problems like cavitation and other noise.

this is a good example where 1 + 1 is not equal to 2 (the proper calculation should use the sum of the AREA, and not based on the diameter), and likewise bigger is not necessarily always better

 

[d0ughb0y]

.

 

[milkman55]

Thanks d0ughb0y, I found that same site and concluded that the 1 1/2" would outflow more than two 1" pipes. I plan to use Sch 26 for the drain only which has a greater inside diameter I believe than Sch 40, so hopefully that will be adequate.

Seths Dad post shows the stats from the calculator which show two 1" drain 600 gph each and the 1 1/2" drains 1200 gph, so I think it should work. I have used most of those calculators and they are great.

I am cutting a hole in the wall and floor and do not want to make it any larger than necessary.

Thanks for the help

 

[sjm817]

Dont use sched 26 on the drain into the basement. Its ok, but if you ever need to cut into it to make a change later, it may be a problem. It tends to crack. I use sched 26 for the Durso's and short run plumbing, but not long runs and something as critical as the display drains.

FWIW, I have a basement sump and ran 3 x 1" Spa-Flex. 2 for the drains and 1 for the return.

 

[milkman55]

sjm817 - thanks for the thought on the Sch 26 being brittle. I know I have used it for sprinkler systems in the past and yes, it can crack easier. I have about 30 ft to run from the display to the sump, so I don't think I am going to spring for that much spaflex.

 

[jh2pizza]

I would run two drains clear to the sump. Ours are 47' of drains. I use a 2" off the hammerhead for a return pump and two 1.5" drains. More than once I was glad I went with the second drain. Saved the house more than you would think.

 

[jh2pizza]

Dont use sched 26 on the drain into the basement. Its ok, but if you ever need to cut into it to make a change later, it may be a problem. It tends to crack.

Not to mention much louder.

I would be very concerned about it cracking. Bump it, jar it, you would never realize its damaged until its too late.