The short answer
A combo system comes with a primary pump and a 12 V backup already plumbed together, often with check valves, so it drops into the basin as one unit. It's the simplest way to add a backup when you replace an old pump.
Systems we cover
- Wayne WSS30VN: 1/2 HP primary and 12 V backup for 16 in or larger basins; battery sold separately.
- Basement Watchdog CITS-50: 1/2 HP cast iron primary with a monitored backup.
- Liberty PC257-442: the 257 primary with a 442 backup, each with a check valve.
Before you buy
- Measure the basin: combos need room for two pumps.
- Budget for a deep-cycle battery if one isn't included.
- Check the discharge size matches your pipe.
Products mentioned
Primary + backup combo · Wayne
Wayne WSS30VN Primary and Battery Backup Combo
1/2 HP primary + 12 V backup.
Primary + backup combo · Basement Watchdog
Basement Watchdog CITS-50 Combo System
Cast iron primary, monitored backup.
Primary + backup combo · Liberty Pumps
Liberty Pumps PC257-442 Combo
Liberty 257 + 442 backup.
Questions readers ask
Does a combo system include the battery?
Usually not; check the listing.
Will a combo fit my pit?
Check the maker's minimum basin size, often 16 to 18 in.