Backflow from Bilge Pump

[donradcliffe]

I have a diaphragm bilge pump, with no backflow.

My shower sump pump has a Rule type pump with a checkvalve to prevent backflow. The problem with the checkvalve arrangement is that the pump has to overcome the head pressure of the water behind the checkvalve in order to start the flow, and if there is any air under the pump, it won't prime. If I have been well heeled over, I have to burp the air out of the system to get my shower sump pump to prime.

Due to the safety implications of a bilgepump system, I would think twice about installing a checkvalve downstream of a Rule (vane) type pump.

[Maddog]

I have a Johnson Pump that has an internal check valve. A flapper that is built into it.