Selecting the proper style and size pump for a submersible pumping application doesn’t need to be a daunting task! Understanding a few key considerations to factor in when making a choice—such as the type of pump, pump operation, horsepower, voltage and phase, and GPM total—can make the selection easier. This information can help you select just the right basic residential or light commercial/industrial submersible pump for your application.
Pump Operation
- Submersible Pump: A pump with the motor and electrical components sealed in a protective housing. This design allows the pump to be used under water or submerged in other liquid environments.
- Sump Pump: Manufactured to primarily remove unwanted drain water from a basement sump pit or drain tile systems where lack of a gravity drain allows water to pool. Sump pumps are rated for ground- or wastewater which is mostly void of solids (nothing more than silt and groundwater solids less than 1/4" in diameter). They’re frequently installed where basement flooding is a problem, and to remove moisture from around foundations in order to prevent mold/mildew build-up. Discharge pipe size ranges from 1" or larger, based on existing drain line applications.
- Effluent Pump: Engineered for “gray” water or wastewater (mostly liquid) applications that contain solids of 3/4" in diameter or smaller. This is often wastewater that has passed through a septic or settling tank and needs to be pumped into an additional system or treatment area. Discharge pipe size ranges from 1-1/2" or larger, based on existing drain line applications.
- Sewage Pump: Mostly used in raw sewage applications or dewatering where up to 2" diameter solids must be passed through the pump. Sewage pumps are often called "ejector pumps" and are used to pump biodegradable waste and water into an existing sewer treatment facility or sewer piping system. Not recommended for household or business use that needs to pump large amounts of non-biodegradable waste which includes plastics, or fibrous materials such as cleaning wipes and hygiene products. Discharge pipe size ranges from 2" or larger, based on existing sewage pipe drainage applications.
- Grinder Pump: Designed to grind raw sewage material, hygiene products, and non-biodegradable materials more efficiently and into much smaller pieces than standard sewage ejector pumps. Grinder pumps are used in large networks of wastewater treatment piping. Typically these pumps have a bolted flange for a discharge connection. Outlet sizes range from 1-1/4” or larger.
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Understanding Horsepower on Submersible Pumps
There are two main factors—GPM and total head—to consider when selecting the horsepower of a submersible pump.
- GPM (Gallons Per Minute): The amount of liquid, in gallons, a pump can remove in a minute at the specified head limit.
- Total Head (head pressure): This is the total maximum height at which a pump can perform before it begins to lose flow. Typically, the greater the horsepower, the more powerful the pump will be. The greater the increment of horsepower typically means the pump will have a greater Total Head and GPM. This makes it possible to pump over long distances in a pressurized, non-gravity fed system. A residential application requires the measurement from the bottom of the collection pit to the point where gravity takes over and the liquid can freely flow. Typically this gravity point is a turn to exit the home or a connection to a larger drain pipe. For example, a basement with the pump emptying into the drainage system just above 8' ceilings and a pit that is 18" deep will have a measurement of 114" or 9.5' of head needed by the pump to perform at its specified GPM.
Understanding Rate of Flow
Most sump pumps require a motor range of 3/10 HP or greater for residential or light commercial/industrial applications. Knowing the rate of flow into the pit is important and can be estimated by the following simple equation. Remember, the GPM of the chosen pump must be larger than the GPM into the pit or the pump will not keep up.
- Sandy soil: The basement square footage divided by 100 and multiplied by 2.50 equals GPM (i.e., basement's sq. ft./100 x 2.50 = GPM).
- Clay soil: The basement square footage divided by 100 and multiplied by 1.25 equals GPM (i.e., basement's sq. ft./100 x 1.25 = GPM).
Effluent, sewage ejection, and grinder pumps require 4/10 HP to 2 HP to transfer or grind solids in wastewater. Typically these pumps have a greater horsepower rating than residential sump pumps. It’s important to know the maximum head limit and the amount of water being pumped per cycle (collection pit gallon rating) when choosing horsepower for a submersible pump.
Power Supply
Submersible pumps come with either a single-phase or three-phase motor, with the most common being a single-phase option. However, all pump styles are available with three-phase motors.
- Single-Phase Motor: Most commonly used for residential applications, a single-phase motor will run a pump with a single AC cycle at one continuous speed. Single-phase pump motors operate on 120V or 240V power supply.
- Three-Phase Motor: Will operate the pump with a continuous series of three overlapping AC cycles. Used in higher horsepower AC submersible pumps, three-phase motors can be used for home and light commercial/industrial applications.
- Existing Pumps: These pumps will have a motor plate or tag which specifies HP, voltage, phase, and discharge and are a good reference for replacing an existing pump.
Pump Switch Style and Function
Choosing the correct switch for a pump is important for extending the life and operating efficiency of a submersible pump. Here are three available switch options:
- Tethered Switch: Liquid/sewage entering a collection pit raises the sealed plastic ball attached to the discharge or vent pipe. When raised to a certain angle, the switch inside the float activates, running the pump and emptying the collection pit until the floating switch end has almost completely dropped down. Tether switches provide an adjustable range for larger pits. They can also be used for fine-tuning pump operation and rest-time between cycles. The easily adjustable length makes tether switches ideal for submersible pumps in residential and light commercial/industrial applications.
- Vertical Switch: Liquid levels raise the float along a single brass, stainless steel, or plastic rod straight up to a switch or stopper which triggers the pump. When the float drops down with the liquid level, it will stop on the rod base or at a pre-set stopper, pulling the rod and switch down which shuts off the pump. Vertical float switches are great for narrow collection pit applications and where On/Off points for the switch need to be adjustable for operation.
- Electronic Sensor Switch: These switches have no moving parts that could get stuck or hung up inside a collection pit. They are used in smaller pits and where the pump doesn’t require a long operating range. Metal sensing probes up to 10" long detect any liquid present.
Whether you need a submersible sump pump, a battery backup sump pump or another pump to ensure you keep things dry, Zoro has the broad selection you need.
Product Compliance and Suitability
The product statements contained in this guide are intended for general informational purposes only. Such product statements do not constitute a product recommendation or representation as to the appropriateness, accuracy, completeness, correctness or currentness of the information provided. Information provided in this guide does not replace the use by you of any manufacturer instructions, technical product manual, or other professional resource or adviser available to you. Always read, understand and follow all manufacturer instructions.