Recommended 1 1/2" sump pump not able to open a 2" check valve on a 2" pipe

[usneddie]

I recently had a new sump pump put in that required a 2" pipe and check valve. My backup recommended a 1 1/2" pipe and check valve. My backup stopped working and I was told it was because it needs a separate 1 1/2 inch pipe and check valve. The main and backup are connected to the same 2" pipe via a Y pipe connector. I have been told the backup is not working because it can't "open" a 2" check valve. Does that sound right? It doesn't make sense to me.

Thanks in advance for help.

 

[Matt30]

Post pictures of how it’s piped

 

[usneddie]

Here you go. I was told it is a 1 - 1/2" Y going into a single 2" check valve and pipe. I was told the backup pump isn't strong enough to push through the 2" check valve. It seemed to be working well when the whole thing was 1-1/2". I just installed a new primary that required 2" pipe and that is when the trouble started. Thanks for your help!

 

[Jeff Handy]

It looks wrong in several ways.

First of all, each pump discharge line needs its own check valve.

If they are sharing one after they join up, the pumped water can just run up to the wye fitting and back down again, because the weight of water being held by the shared check valve is causing resistance, and some or all of the pumped water will take the easier flow path right back into the pit.
The main pump might be able to pump some water past the check valve, because it is stronger, even though some water is short cycling right back into the pit, out the bottom of the other pump.

Secondly, it looks like your main pump is not supplied with a 2 inch discharge, it is a normal 1 1/2 inch pipe down in the pit.
The discharge pipe only changes to 2 inch pipe several feet later, after the shared check valve.
If the discharge fitting of your main pump is 1 1/2 inch, it does not need 2 inch pipe.

Also, each discharge line needs a small approx 1/8 inch hole (or slightly smaller) neatly drilled into the side of it, down low enough in the pit that water will spray out of it but will not splash out of the pit.
And the angle of the hole should direct the water slightly downwards, to minimize splashing.
And the holes should be placed so as not to squirt water onto a float switch.

These little holes allow the water in the lower end of the pipes to drain back into the pit, so the pumps can more easily prime themselves and start pumping.

It is better if you ditch that pit cover, and have both pump discharge lines come out of the pit at least a few inches, then a high quality check valve on each, then a few inches more straight up, then put a 45 elbow on one, and join them in a wye going to a common discharge.

I usually put the backup pump on the 45 elbow line, but there is debate about which way is best.

Use a heavy rubber coupling (not a check valve) to join the upper end of the common discharge to the existing discharge line, so you can more easily take everything apart as needed.
You can get a plastic sump cover with a slot cut out of the center, which will slide right over your new double discharge pipes.

So basically, everything needs to be totally redone.

 

[Jeff Handy]

Here is a pretty good diagram.

I would add a heavy rubber coupling above the wye connector, to be able to take everything apart more easily.

 

[Jeff Handy]

The two inch main discharge pipe is ok to keep as is, after the smaller pipes join together and connect to it.

 

[usneddie]

The two inch main discharge pipe is ok to keep as is, after the smaller pipes join together and connect to it.

Thanks so much for explaining all of that! That really helps. I am going to get it all redone as you suggested.

 

[Jeff Handy]

A cover like this will slip on and off easily, for testing and maintenance.
The picture is actually showing the cover from below, to show reinforcing ribs