Sump Pump - Pump Selection

Pump Selection

The selection of a sump pump will rest heavily on the application in which it will be used. To select the appropriate sump pump, consider the following:

• Automatic vs. manual operation — Selection of a manual sump pump means that one will turn the pump on and off when appropriate. Selecting an automatic sump pump means that a switch is wired to the sump pump to turn it on or off at appropriate water levels. Automatic switches include pressure switches, low level pressure switches and float switches.
• Power — Sump pump motive power will vary from 1/4 horsepower to multiple horsepower.
• Head pressure — The head pressure of a sump pump describes the maximum height that the pump will move water. For instance, a sump pump with a 15 ft maximum head (also called a shutoff head) will raise water up 15 ft before it completely loses flow. Technically, head pressure is defined as an expression of a pressure in terms of the height of fluid; P = yρg, where y is the fluid column height, ρ is fluid density and g is the acceleration of gravity. Other considerations may be added to overall head pressure, including loss from elbows/bends and friction loss from long horizontal runs.
• Power cord length — It is important to consider the length of the cord of any special switches that may be connected to the pump. Running a more powerful electrical motor a long distance from the main service panel will require heavier gauge wires to assure sufficient voltage at the motor for proper pump performance.
• Phase and voltage — Sump pumps powered from the AC mains are available with single-phase three-phase motors. rated for 110-120, 220-240, or 460 volts. Three-phase power is typically not available in residential locations.
• Water level sensing switch type — Pressure switches are fully enclosed, usually inside the pump body, making them immune to obstructions or floating debris in the sump basin. Float switches, particularly the types attached to the end of a short length of flexible electrical cable, can get tangled or obstructed, especially if the pump is prone to movement in the basin due to torque effects when starting and stopping. Pressure switches are typically factory set and not adjustable, while float switches can be adjusted in place to set the high and low water levels in the sump basin.
• Backup system and alarm — If redundancy and an alert system are vital for operation of your sump pump, consider a backup system and/or alarm.