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Author:
jmr1068204 (GA)
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. I'm basically replacing two pedestal pumps that rattle the room above when they come on. Each new 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 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 switch on one and a float switch on the other for higher volume.
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 pvc pipe during the winter discharges.
So far, I've been told 2 1/2" or 3" by the guy at the pump place.
Another person who does plumbing told me each gpm = 2 fu, so both pumps running = 220 fu. They said that 220 fu minimum size discharge is 4" with both pumps tied in. So, they recommended 3" minimum for each pipe coming out of the pump and then both tying into a 4", but the pump discharge outlet is only 1 1/2" per pump.
How do I know who to listen to? A 3" pipe is pretty huge for water coming out of a sump. A 4" pipe would look like I had a sewer pipe running across the top of the yard. lol
Got any advice?
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.
Edited 1 times.
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Author:
packy (MA)
i would recommend that you contact the pump manufacturers engineering department. they should have a computer program that they can simply plug in your numbers and have an answer for you.
remember that changes in direction also factor into calculations.
somrthing tells me that 1/3 HP pumps do not need 3 inch pipe.
also ask them about what type check valve they recommend and where they like to see it located.
lastly, i think a weep hole is necessary. drill it at an angle so it sprays downward when the pump is pumping.
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