1. Why are there two sump pumps installed in a pit?

2.Is it because one pump is a back up or is it because if there is a lot of rain then the two pumps can be pumping at the same time ?

3. If both pumps are pumping at the same time wouldn't the riser or vertical pipe going up after the check valve need to be larger to handle the both pumps pumping?

4. I believe the manufacturer calls for 1 1/2 inch discharge pipe. But a 1 1/2 inch discharge doesn't seem like it would handle both pumps pumping at the same time ?

5. Or is the 2nd pump just meant for a back up?

6. Does one pump sit higher so that the pump is not constantly submerged in water causing rust around the impeller?

2) Second pump is a backup
5) Yes
6) No. The second (backup) pump sits higher so that its switch turns on the pump only when the primary pump has failed and the water level is high. It is so humid in the pit that it does not matter if the impeller is submerged or not, it will corrode at the same rate. Impellers are usually stainless steel or plastic.

Thank you George from Canada !



Edited 1 times.

Usually there are two pumps for safety reasons. The first one is the main unit, and the second acts as a backup in case the main fails or if the water level rises too quickly. The 1½ inch pipe is fine since both rarely run simultaneously, and even then, the flow is not constant.