Why does water leak by the new check valve(spring style) on my secondary sump pump?

What is location of leak? Is it coming from where valve is attached to pipe?

Lets us know. More detail.

Chuck

Is the check valve installed vertically? These valves work best when there is pressure pushing the water back againist the flapper. If there is little head pressure they will weep.

It is leaking out of the new pump. It leaks out for about 2-3 seconds every 45-60 seconds. The length of pipe (1 1/4 ") is about 12 feet including elbows, so I figured roughly 24 pounds of pressure on the check valve which is a brass spring check device. It is mounted horizontally( no room to go vertical}. Since it is a spring check, I would think it would function fine by mounting it horizontal.

None of the check valves I install can work mounted horizontally