Sump Pumps

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A sump pump is an automatic water pump powered by an electric motor which removes drainage, excluding raw sewage, from a sump or low point. There are two basic kinds of sump pumps: pedestal and submersible. Either will work well with proper maintenance. Pedestal sump pumps are powered by an electric motor which sits on top of a pedestal. The pump itself sits down in the sump, but the motor sits on top, out of the pit. A pedestal pump motor is not designed to get wet. The pump is turned on and off by a ball float. One advantage of this type of pump is that the on/off switch is visible, so the action of the ball float can be easily seen.

Credit: Flickr | pdz_house | CC 2.0 Credit: Flickr | pdz_house | CC 2.0

Submersible pumps sit at the bottom of the pit; therefore the motor is designed to be submerged in water and is completely sealed against water. The on/off switch is attached to the pump and can be either a ball float connected to an internal pressure switch or a sealed, adjustable, mercury-activated floating switch. Both are reliable, but the floating switch requires a larger diameter sump. If the sump diameter is less than 18 inches, the floating switch or its cord could become entangled with the piping or pinned between the pump and sump. Either type of pump should have a check valve on the water outlet pipe so water doesn't flow back in the sump when the pump shuts off. Without the check valve, water would flow back and forth, and could cause the pump to turn on and off more frequently than necessary, decreasing the life of the pump.

Sump pumps are used for two basic purposes, but both serve as the home or building owner’s main line of defense against having the low point of the building fill up with water. One purpose is for regular drainage of a sump into which water is conducted. An example of this situation would be the sump or the low point of a structure in an area with a high water table where the sump is actually below the water table. Water can be an extremely destructive force. It can seep into your basement through windows, cracks in the foundation, or improper grading, and can cause a significant amount of potentially expensive damage. In a growing neighborhood, sometimes the addition of a number of basements can sufficiently raise the water table to require a sump pump where there didn’t use to be the need for one. Water can also render your home uninhabitable from mold formation, wood rot and plumbing problems, including sewage backups, all of which may require major repair work and/or renovations.

The sump may be connected to drain tile that drains the footings of the house. Drain tiles may be under the entire basement, or just the area where the sump is located. Many houses have tiling installed only around a portion of the house. The water that drains into the sump must be removed, and this is accomplished with a sump pump. As a foundation drain delivers water to the sump, the sump periodically is energized and removes the water.

The other purpose of a sump pump is to remove excess water from a sump or low point when unusually heavy rains flood the area. When water is not properly diverted away from the outside walls and foundation of your home, it can saturate the surrounding soil and gradually seep into your dwelling. An example of this is where the downspouts have not been equipped with a splash block. In this situation, the sump pump may run continuously or until the water is removed. If your basement is prone to flooding, then a reliable sump pump is essential.

It should be noted that a sump pump alone may not provide absolute protection. Since electricity is required to power the motor for the pump, if the power lines in an area are out of service for any reason, no power means no sump pump working to remove water. Because of the potential for this situation, it may be wise to consider several other backup power options for the sump pump. One option would be to install an emergency generator that could power all of a house, or simply the key systems such as the sump pump. It is strongly suggested that a licensed electrician install the generator. There have been instances when the power lines in an area were being worked on and the power company shut off a grid, only to have an improperly installed generator back feed the grid and electrocute a worker. Another solution for loss of power is to install a backup sump pump. Many people prefer this option to a generator if they are away from home for significant periods during the year. A backup sump pump is designed to operate only in the event of a power failure. Backup sump pumps are usually direct-current (DC) battery driven pumps which can supply pumping power for short periods of time. The batteries are charged by a trickle charger connected to the house electrical power. Many manufacturers sell backup pumps. All sump pumps need to be checked on a regular basis, but once per year is the minimum.

To check a sump pump, first make sure the discharge pipe is not frozen shut or plugged, and that the pump adequately directs water away from the house. Water should be directed at least 20 feet away from the foundation, and not in the direction of a neighbor’s yard or into a window well or a septic system drain-field. Never discharge sump pump water into your floor drain. Remove the lid of the sump (if the sump has one) and use a flashlight to check the sump itself and verify that the pump intake is not plugged. If it is plugged, remove the blockage. For pedestal pumps, the intake is on the top of the pedestal in the water. For submersible pumps, the intake screen is just below the motor. Normally, the intake is visible even in water, but if not, use your fingers to make sure the intake is not plugged. In some sumps, the inlet or inlets from the tile(s) are near the bottom of the sump. In this case, temporarily plug the inlet or inlets. Next make sure the pump is plugged in. Then slowly pour water into the sump. Try to simulate the speed that water normally would flow into the sump. Watch the on/off float switch's action and listen to the pump. Make the pump turns on and off at least twice. If the pump doesn't sound right, fix it as soon as possible. An older sump pump motor can be burned up by running with a blockage, but all newer sump pump motors have thermal protection built in to protect the motor if the pump outlet becomes plugged. If the motor becomes too hot, a thermal relay will trip and shut off power to the motor. Disconnect electricity from the pump and let it cool down. This should take 15 to 30 minutes. Thaw out the pipe while you're waiting or remove the blockages, then reconnect the electricity.

There is no correct or incorrect size for a sump pump. One should be aware that the purpose of a pump is to lift water from one level to another. This is called head. If a pump head is less than the distance the water must be lifted, then it simply will not do its job.

Last modified on Wed, Sep 26, 2012
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