DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Plumbing Forum > What's the rule for PVC pipe size vs flow?


Reply
 
Thread Tools Search this Thread
Old 11-27-2016, 09:24 AM  
jmr106
Established Member
Join Date: Dec 2015
Posts: 279
Liked 44 Times on 38 Posts
Likes Given: 5

Default What's the rule for PVC pipe size vs flow?

In the near future, I'm going to be installing a large sump basin (50 to 70 gallons or so) in the crawlspace with two new pumps that are more efficient and will kick out even more water with little noise. Each pump will have its own pipe with a roughly 7' initial head, then both will run about 5 feet horizontal and go out of the crawlspace to the outside, make a 90 degree turn and somewhere around that area just outside of the house it will split into a single PVC pipe to continue the 20-25ft run out into the back yard. The pumps can handle it and are designed for up to a 25ft head with no problem.

I'm doing this joining of the pipes outside because if the two pipes joined a single larger pipe inside of the crawlspace and something happened to the larger main pipe, that would be a big failure. However, with two separate pipes going outside, there is a backup and it would at least get the water outside of the house even if the split to the large pipe came loose outside of the house. I just like to plan ahead of time.

I talked to the guy at the place where I'll be buying the pumps. He told me, "I would suggest that you tie those two discharge pipes to a minimum 2-1/2" or even 3" PVC pipe for maximum performance. As long as the horizontal pumping distance is not extreme, you will be fine." Is it really that simple - doubling the pipe size to whatever the main pipe is to be? My research hasn't been coming up with that.

One will be primary and one for backup. Each pump can kick out about 3,330GPH, or roughly 55GPM. In the rare crazy rain event where both need to come on and 110GPM is going through one pipe, I want to make sure it is big enough. However, apparently a pipe that is too big has the opposite effect - losing pressure to push the water out fast enough and with enough force.

Suggestions? I have done Google searches and such, but there always seems to be conflicting information. One place says x thousands of gallons should flow through x size pipe, and then another place says something totally different. I want maximum flow rate for each pump without losing the pressure.

I really need to angle the entire horizontal pipe run (the part that runs along the ground) a little bit somehow, so that nothing freezes in the pipe during the winter discharges.



Last edited by jmr106; 11-27-2016 at 09:32 AM.
jmr106 is offline  
 
Reply With Quote
Old 11-27-2016, 10:17 AM  
frodo
Senior Member
 
frodo's Avatar
Join Date: Aug 2008
Posts: 2,847
Liked 1075 Times on 840 Posts
Likes Given: 379

Default

each gpm = 2 fu both pumps running = 220 fu

220 fu minimm size discharge is 4'' both pumps tied in

3'' minumum seperate


Click image for larger version

Name:	chart.jpg
Views:	77
Size:	24.8 KB
ID:	12920  
__________________
Cogito, ergo armatus sum.

My advice is free, If I have helped you and you wish to help the site out with a gift
use this link
http://www.houserepairtalk.com/forum/...faq=supporting

Last edited by frodo; 11-27-2016 at 10:40 AM.
frodo is offline  
 
Reply With Quote
Old 11-27-2016, 10:38 AM  
jmr106
Established Member
Join Date: Dec 2015
Posts: 279
Liked 44 Times on 38 Posts
Likes Given: 5

Default

Quote:
Originally Posted by frodo View Post
sump pump or effluent pump

storm water or sewage
Sump pumps. After a lot of research, I'm going with dual 1/3HP Ion Storm Pros. Stainless steel. Total 4.5 running amps each, but kicks out as much as some 1/2HP pumps that use way more amps. It utilizes a digital level control, solid state with no moving parts to wear out. I'll either elevate one above the other somehow as strictly a backup pump sitting on something else in the basin. Or maybe I'll use the digital on one and the float switch on the other for higher volume.






Impeccable reviews and pretty much special order pumps.

I'm technically going to be using a sewage basin for the sump basin, because the regular sump basins aren't typically made to that size or they want $500 for an equivalently-sized sump basin that looks virtually the same as the sewage basin.

Storm water.

Last edited by jmr106; 11-27-2016 at 10:56 AM.
jmr106 is offline  
 
Reply With Quote
Old 11-27-2016, 10:52 AM  
frodo
Senior Member
 
frodo's Avatar
Join Date: Aug 2008
Posts: 2,847
Liked 1075 Times on 840 Posts
Likes Given: 379

Default

make sure it seals tight, it is a blooming high way for crawly things
__________________
Cogito, ergo armatus sum.

My advice is free, If I have helped you and you wish to help the site out with a gift
use this link
http://www.houserepairtalk.com/forum/...faq=supporting
frodo is offline  
 
Reply With Quote
Old 11-27-2016, 02:44 PM  
jmr106
Established Member
Join Date: Dec 2015
Posts: 279
Liked 44 Times on 38 Posts
Likes Given: 5

Default

Quote:
Originally Posted by frodo View Post
make sure it seals tight, it is a blooming high way for crawly things
The sump pit itself? I'm planning to get the matching lid with the custom holes with rubber gaskets around them, a hole for electrical, etc. Trying to figure out if there is some kind of flap that I could put on the end of the discharge pipe that would close down and prevent any critters from getting into the pipe when it isn't discharging. Sort of like what we have on the dryer vent.

Are the gate valves simply there as a means to keep any water in the pipe above from getting everywhere if a pump needed to be changed out or one side turned off for some reason?

Is a weep hole really necessary? I have been reading a lot about people drilling a weep hole in the pipe just above where it attaches to the pump to prevent some sort of air lock, but my current pipes do not have that. Haven't had any air lock issues on either pedestal pump.

Last edited by jmr106; 11-27-2016 at 02:46 PM.
jmr106 is offline  
 
Reply With Quote
Old 11-27-2016, 03:43 PM  
frodo
Senior Member
 
frodo's Avatar
Join Date: Aug 2008
Posts: 2,847
Liked 1075 Times on 840 Posts
Likes Given: 379

Default

use a 4'' pvc backwater valve

code calls for the valve to be installed,,,

weep hole, do what the manufacture of the pump requires, some call for it others do not
__________________
Cogito, ergo armatus sum.

My advice is free, If I have helped you and you wish to help the site out with a gift
use this link
http://www.houserepairtalk.com/forum/...faq=supporting
frodo is offline  
 
Reply With Quote
Old 11-27-2016, 04:07 PM  
frodo
Senior Member
 
frodo's Avatar
Join Date: Aug 2008
Posts: 2,847
Liked 1075 Times on 840 Posts
Likes Given: 379

Default

you NEED to wire your pumps to lead/lag

pump 1 comes on, pump 2 will come on if high water is detected

then the next cycle

pump 2 comes on, pump 1 will come on if high water is detected

then next cycle

pump 1 on pump 2 if needed

etc etc...

you do NOT want one pump sitting there not being used
Click image for larger version

Name:	cyberheater2.jpg
Views:	52
Size:	18.5 KB
ID:	12924  
__________________
Cogito, ergo armatus sum.

My advice is free, If I have helped you and you wish to help the site out with a gift
use this link
http://www.houserepairtalk.com/forum/...faq=supporting
frodo is offline  
slownsteady Likes This 
Reply With Quote
Old 11-27-2016, 06:27 PM  
jmr106
Established Member
Join Date: Dec 2015
Posts: 279
Liked 44 Times on 38 Posts
Likes Given: 5

Default

Quote:
Originally Posted by frodo View Post
you NEED to wire your pumps to lead/lag

pump 1 comes on, pump 2 will come on if high water is detected

then the next cycle

pump 2 comes on, pump 1 will come on if high water is detected

then next cycle

pump 1 on pump 2 if needed

etc etc...

you do NOT want one pump sitting there not being used

There are some pump controllers that I have seen that do this. That's about the only way that I know of to do that. Unless we're having a really rainy season, the pumps don't get a lot of continual use. Our issue is more so...when it decides to rain for 2-4 days straight. The pumps might come on for a day or two after that, maybe averaging 30 gallons per minute coming in when things have calmed down. Or a random thunderstorm that dumps so much water at one time that I get 80-100 gallons per minute flowing in for maybe 20-30 minutes and then it goes away. I'm going to be using a basin surrounded by gravel. Due to the size of the basin that I'll be getting, I'll have to punch holes in it myself. I'm trying to figure out a way to have holes in the basin so that water will flow in and the basin won't push up, but also...figuring out how the heck I would test it if any water that you poured in would seep out of the holes into surrounding gravel. Both of the pumps will need to be tested regularly since it doesn't get water flow all of the time. I could leave some of the bottom of the basin solid without holes in it, but I'd have to make sure that it doesn't cause it to float.

Last edited by jmr106; 11-27-2016 at 06:59 PM.
jmr106 is offline  
 
Reply With Quote
Old 11-27-2016, 08:17 PM  
frodo
Senior Member
 
frodo's Avatar
Join Date: Aug 2008
Posts: 2,847
Liked 1075 Times on 840 Posts
Likes Given: 379

Default

not following....are you installing an area drain or a sump pit

if its a sump pit, the tank sits below the ground, the drainage pipe enters it at about the top 1/4 area

https://agrimart.net/4-poly-bulkhead...V50aAk3_8P8HAQ

look around, google you can find one cheaper
Click image for larger version

Name:	iui.png
Views:	42
Size:	6.3 KB
ID:	12925  
__________________
Cogito, ergo armatus sum.

My advice is free, If I have helped you and you wish to help the site out with a gift
use this link
http://www.houserepairtalk.com/forum/...faq=supporting
frodo is offline  
 
Reply With Quote
Old 11-27-2016, 09:32 PM  
jmr106
Established Member
Join Date: Dec 2015
Posts: 279
Liked 44 Times on 38 Posts
Likes Given: 5

Default

I'm tackling an issue in an icky crawlspace that I've had other threads about. Its a dug-out portion of a crawlspace approximately 15'L x 4'W x 3'H with a retaining wall around it. 2-3 days of rain and the rain comes in through the wall from seemingly all sides. Suspected that an old septic tank about 8-10 feet outside of the house (which has been found and filled with dirt since the last rainfall that triggered the pumps) may had something to do with it, as a potential "water flow hole" was found in a corner of the outside of the wall months ago. Got about 2.5 inches of rain coming up over the next few days, so if it triggers the pump, I'm going to see if a lot of the water was coming from the old septic tank that may have been filling and making its way to the crawlspace a few feet underground.

The only solution found after months of pondering and research was to fill that whole area with drainage gravel and install a big sump basin and strong pumps. The flow may be less now, but with a saturated ground when it rains, I still expect some to come in. So I'm installing a proper sump (which it doesn't have at the time) to deal with it.

So in this case, we're talking a ton of gravel all the way around and no sump pit. Just a basin. Water would come from all directions in the gravel, so a basin with holes around it is needed to let the water in. There is no proper water outlet pipe to connect to the basin, so I'm struggling to find a way to make a basin that won't float itself out of the gravel and yet will somehow allow me to keep a bit of water in it when I want to test the pumps. Otherwise, putting water in the basin with holes in it would make it just flow out into the surrounding gravel that the basin is in. I could leave maybe a foot or so of the bottom of the basin without holes in it, but the only concern with doing that is the potential for it to float. Of course, each pump is about 25+ pounds. I'll probably stick some kind of brick or something in there to elevate pump two so that it alternates somehow, or I'll get a pump controller of some sort. Working with the manufacturer on that currently to see what they recommend. Most basins are little and therefore the drawdown is about 6" to 10" max for the average pump. I'd prefer to pump out way more than that at once to prevent short cycling and just to keep up with any heavy water flow that it can get sometimes.



Last edited by jmr106; 11-27-2016 at 09:38 PM.
jmr106 is offline  
 
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Similar Threads
Thread Thread Starter DIY Home Repair Forum Replies Last Post
Standard Size Tub Spouts do not fit my pipe mbzhang Plumbing Forum 2 10-27-2014 07:00 PM
Pipe Sizing & Flow Meters kok328 Plumbing Forum 12 03-28-2014 04:27 PM
Size of pipe (3/4" or 1/2")? frankflynn Plumbing Forum 5 12-29-2013 03:42 PM
Actual size of oval type B vent pipe joybird HVAC 0 10-25-2009 08:54 AM
1/3, 2/3 rule TxBuilder General Chit-Chat 2 09-30-2006 06:53 PM



Newest Threads