A sump pump relies on an automatic sensor to manage the water level in the sump pit and prevent basement flooding. This sensor is the float switch, a buoyant component that rises and falls with the water level. The float switch initiates the pump’s operation when the water reaches a set maximum height and stops it when the water is removed. A correctly set float dictates the pump’s cycling behavior, which directly affects the unit’s longevity and its ability to keep the basement dry.
Understanding the Need for Adjustment
Adjusting the float is necessary when the pump exhibits behaviors that compromise its efficiency or lifespan. Short cycling is a common issue where the pump turns on and off too frequently, often running for only a few seconds. This rapid cycling increases wear and tear on the motor and components. Conversely, a float set too high may cause the pump to fail to turn on until the water level is close to overflowing the pit.
Another sign requiring adjustment is when the pump runs continuously after the pit has been emptied. This causes the pump to operate without water, known as “running dry,” leading to overheating and premature failure. Before touching any components inside the sump pit, disconnect all power by unplugging the unit. This safety step eliminates the risk of electrical shock and allows you to inspect the pit for obstructions, such as debris or tangled cords, that could be restricting the float’s movement.
Step-by-Step Float Adjustment
The mechanics of adjustment depend on the specific type of float switch installed, with the two most common being tethered and vertical floats. Tethered or ball floats are buoyant balls connected to the pump or discharge pipe by a flexible cord.
To adjust a tethered float, change the length of the cord between the float and the fixed tether point. Shortening the tether decreases the pumping range, causing the pump to turn on and off sooner. Lengthening the tether increases the range, allowing the water to rise higher before activation, which can reduce short cycling. The goal is to set a wide enough range to prevent frequent cycling while ensuring the ‘off’ point drains the pit effectively without the pump sucking air.
Vertical or column floats operate by sliding up and down a fixed rod attached to the pump housing. Adjustment is achieved by moving a plastic or metal clip, often called a stopper, that sets the vertical travel limits. Moving the top clip higher allows the water to rise to a greater height before the pump turns on. Adjusting the lower clip dictates the water level at which the pump turns off. Vertical floats are well-suited for smaller sump pits where a tethered float might get stuck against the side walls.
Verifying Pump Cycling
After making adjustments, restore power to the pump and verify the new settings are correct to ensure efficient operation. The most effective testing method is to manually simulate a heavy rainfall event by slowly filling the sump pit with water, typically using a hose or buckets. As the water level rises, observe the exact point at which the float switch triggers the pump to turn on, which is the ‘on’ point.
Allow the pump to run through its full cycle and note the water level when the pump automatically shuts off, the ‘off’ point. A successful adjustment means the pump turns on well below the inlet pipe and runs long enough to effectively clear the pit, leaving only enough water to cover the intake screen. If the pump still short cycles or runs dry, immediately disconnect the power and make small, incremental changes to the float position, repeating the fill-and-observe process until the desired cycling behavior is achieved.