On Apr 18, 9:42�am, " wrote:
Had a Zoeller Model 98 sump pump with a Flotec checkvalve. *All was
good and the pump operated quitely.

This weekend, I added a Basement Watchdog Big Dog battery backup pump
to supplement my Zoeller. *I wye'd off the 1.5" main line and added
two new flapper type checkvalves from Lowes *(each one about 12" above
the pump). * I discarded the old Flotec flapper type checkvalve.

The system seems to work fine. *Only difference is that now when the
Zoeller cycles off, I hear a mild clunk that I never heard before.
Any idea how I might quiet it down?

BTW, there are 1/8" downward angled weep holes just below each of the
checkvalves to prevent air lock.

Thanks,
Kevin

probably the check valves.

Honestly if I were you I would run a completely seperate line for the
backup pump. In case that single drain line ever fails or a check
valve malfunctions where the pump could just cycle water endlessely.

Just get the water out of the immedioate area, like out a wall if it
can run away from building.

I am a belt AND suspenders kinda guy.