One Level, One Switch

• Pump systems that operate around a single level point tend to cycle often because they wait until a specific level point is reached to turn on the pump. Although switch manufacturers build a small amount of mechanical hysteresis, or detent, into the switch system, the level gap is sometimes very small between the point they turn on and the point they turn off. A large pump in a small pit with a small switching gap results in continual short cycling and excessive wear of all system components. This situation can be nerve wracking to home owners who are trying to get to sleep in an otherwise pin-drop quiet house.
  
  

Two Levels, One Switch

• Differential gap level systems employ the principle of two distinct level points that are located far enough away from each other so that the capacity of the sump pit can be used to advantage to spread out the system's cyclical operation. An effective system can be implemented from a toilet fill ball float, some simple hardware and a maintain-type toggle micro switch (stays up or stays down once switched like a wall light switch) rated at 125 VAC and 15 AMPS.
  
  

Construction

• The idea is to implement a float strategy that will turn on the pump switch at the high level and turn it back off at the low level. Find or purchase (less than $5) a traditional toilet tank fill valve float. Purchase a thin nylon threaded rod (usually 5/16 inch by 18 thread) about 3 feet long, and a handful of nylon hex nuts and washers to go with it. Thread the ball float on the end of this rod. The ball will be lowered into the sump pit on the end of this rod to the bottom of the pit. The rod should be routed through a vertical motion guide such as a 1-foot long sprinkler riser, so that the top foot or so of the rod protrudes out the top end when the ball is on the bottom of the pit. Affix two small switch-actuating brackets onto the threaded rod using the jam nuts and washers. Mount the toggle micro switch so that the top bracket flips the switch down (pump off) when the float is on the bottom, and the bottom bracket flips the switch up (pump on) when the float comes up about 8 to 10 inches. Wire the pump to the switch per code and cover with an insulating shield or small enclosure.
  
  

Operation

• Make sure there are no binds in the switch system's movements, and that the switch action is positive and smooth. Test with water from a hose several times to assure overall correct operation of the homemade level system.