I've got an active sump pump in MN. The main pump works well. I've also got the basement watchdog battery backup pump. I haven't been able to get the backup to pump water. It seems to run when I disconnect the main pump and fill the hole with enough water to activate the backup float switch. It also runs on battery power or when plugged in. I replaced the pump recently to see if that would pump water and it did not. Same behavior with either pump. FYI -- We aren't certain if the backup has ever pumped water. We had it installed by a plumber 3 years ago but failed to properly test it post installation. Ooops! Let me know any ideas on what might stop a backup pump from pumping water. We don't have a check value in place. Thanks!

if there is no check valve then when the backup pump pumps, the water will just go into the tee and down into the sump hole.
there must be a check valve above the main pump but below the tie in point of the back up discharge.



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