So this weekend I installed a battery powered back up sump pump. Here's my set up: one discharge pipe going out of the house, a Y-joint splitting to the main pump and back up, a check valve on the pipe going to to each pump, and finally the two pumps sitting side by side in the sump. The problem is that after my main pump runs, I get a sound of water coming back down into the pipes that I never had before. Does this sound like some sort of check valve problem? Both pumps will pump water out and the flow arrows are pointed in the right direction, so I know they're both installed correctly.

Thanks...

 

Sorry... not quite clear on your setup.

So, from the ground up, you have:
- a backup pump connecting to a Y
- a main pump connecting to that same Y
- a single check valve _above_ the Y?
- a discharge pipe going up from the check valve and then out of the house
?

If so, it sounds to me just like, when the water is being pumped, some of it is getting pushed by the check valve's natural resistance into the backup sump pump's pipe and then, when the flow stops, the leftover water just sloshes back down (some of which is normal, anyway, with a check valve).

Did you drill a 1/8" hole at the base of the pipes to each sump pump? As I understand it, this is standard practice when using a check valve, as the hole helps to prevent air lock. And perhaps it will allow some of the water accumulating in the backup pipe to drain while the main pump is going, possibly avoiding some of the sloshing return when the pump stops. If you do this, note that I've always seen it recommended that you drill upwards at a 45-degree angle from the pipe.

 

I have 2 check valves...

Ground up:
1. main pump next to back up
2. check valve on main pump discharge and another check valve on back up pump discharge.
3. Y Joint combining the two discharges into one.
4. Discharge exits house.

So I have 2 check valves...one on each pump before the Y joint.

 

Gotcha. Well, my $.02 is that it's normal. I think what is happening is this: when the pump is running, it pumps water up and out, while the leg of the Y going to the backup sump pump's check valve stays relatively empty. When the pump stops, the water rushes back down to fill up the empty backup sump pump's pipe. You didn't have this noise before because, with a single pipe, there was no empty space for the water to flow back down into after the pump stopped operating - the check valve would close, and the water would stay where it was.

I would only worry about the health of your check valves if:
1) the water is not getting pumped out (indicating the check valve was stuck shut - obviously not happening in your case)
or
2) the water is getting pumped out, but then an overly large amount of water is flooding back down into the sump pit after the pumping has stopped (indicating the check valve was stuck open - I'm guessing this is also not the case with you)

 

It is normal..even if you have 1 pump only it is normal..even if you didn't hear it before.

 

Well...I checked out both my check valves...no problems. So I guess it's normal.

I'm figuring that the water is being siphoned from the backup portion of the pipe, and then when the pump turns off, that is what is pouring back down the pipe to the check valves.