Selecting the right Sump Pump

Firstly, what is a Sump Pump?

A sump pump is a submersible pump used for drainage that removes water from a sump pit. A sump pit, commonly found in the home basement, is a man made pit in the ground to collect water. The water may enter from drains funnelling into the pit, or may arrive from natural ground water in the earth.

How are sump pumps typically used?

Sump pumps are installed mostly where basement flooding is a issue. They pump water away from the house to any place where it no longer presents a hazard, such as a municipal storm drain or dry well. Older properties may have their sump pumps connected to the local sewer, but this is tends to be frowned upon now because it may overwhelm the sewage treatment system. In some cases though, a sump pump is used when a lower floor is below the sewer lines, to pump greywater or blackwater waste from that floor to the lines. Other common applications are on a building / construction site or around the home, ie. pumping out a swimming pool etc.

What types of sump pumps can I buy?

Automatic or Manual. An automatic sump pump has a float switch attached that activates the pump when the water reaches a certain height and turns the pump off when the sump pump has drained the water. A manual sump pump must be turned on and off manually, and you will find on some models you can pump down to approx. 3mm with a manual sump pump.

The selection of a sump pump depends on the application in which it will be used. To select the appropriate sump pump; consider the following factors:

  1. Automatic vs. Manual Operation: Selection of a manual sump pump means that you 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 and float switches.
  2. Horsepower/kilowatts: Sump pump horsepower will vary significantly depending on the pump duty required.
  3. Head Pressure: The head pressure of a sump pump describes the maximum height to which the pump has to lift water. For instance, a sump pump with a 15m max head (also called a shutoff head) will pump water up 15m before it completely loses flow. Other considerations may be added to overall head pressure, including loss from elbows/bends and friction loss from long horizontal runs.
  4. Cable Length: The cable length of a sump pump describes the length of the power cord. It is also important to consider the length of the cord of any float switches that may be connected to your pump.
  5. Phase & Voltage: Sump pumps are available in single and three phase.
  6. Backup System & Alarm: If redundancy and an alert system are vital for operation of your sump pump, consider a backup system and/or alarm.

Sump Pump Replacement

First make sure the pump is disconnected from the power source before you handle or clean it. This is a very easy Do-it-Yourself project.

* Match HP (motor horsepower) with the previous model most pumps have a manufactures’ tag or label that provide this information and the model number.

* Determine and match the discharge pipe size.

* Determine and match the correct length electrical cord.

New Sump Pump Installation

The following instructions are general instructions for basic sump pump installation. Always follow the manufacturer's installation instructions.

  1. Know that your sump pit must also accommodate a control such as a vertical float switch or tethered float switches. Larger pits can accommodate both.
  2. Power requirements can be estimated by how high and how fast you want to pump the water or by viewing performance curves.
  3. The electrical outlet should be near enough for the manufactures electric cord to reach without an extension.
  4. Typical submersible sump pumps have a three-pronged, grounded plug and a 240-volt single-phase motor with overload protection.
  5. For greater pump performance or certain existing electrical service other motor electrical detailed wiring is convenient.
  6. A check valve is always recommended on the discharge pipe to prevent water from returning into the sump pit.
  7. A basin with lid can help organize the various inlet piping, outlet piping and electrical cords.
  8. Alarms can be considered to alert in the event of pump or electrical failures.
  9. An Automatic Sump Pump Back-Up System provides extra protection in the event the primary sump pump fails, an obstruction in the sump pit blocks flow, or a power outage occurs. It will also function as an alarm system if the primary pump fails to empty the sump pit.

Reading a Pump Curve

Pump Curve A pump curve tells you the flow performance (measured in litres per minute) of a pump relative to the head pressure. To read a pump curve, you must first examine the units of measurement used along each of the displayed axes. The pictured pump curve displays head pressure in metres or kPa (along the left-side y-axis) and flow (along the bottom x-axis). Increased head pressure is indicated as you travel up the y-axis. The flow performance is indicated in litres per minute (along the lower x-axis). This is an indication of the output flow of a pump.

The pump curve is read by first determining the head pressure of the application in which the pump will be used. Once you’ve determined your head pressure, simply follow the head value you have selected from the y-axis horizontally to where it intersects with the pump curve line. From that point, move vertically to the flow measurement on the x-axis. The pump curve pictured indicates that at 6 metres head the pump will move 40 litres per minute

 

Sump Pump Maintenance

Sump pumps must be maintained. Typical recommendations suggest servicing them every year. Pumps running frequently due to higher water table, water drainage, or weather conditions should be examined more frequently. Sump pumps, being mechanical devices, will fail eventually, which could lead to a flooded basement and costly repairs. Redundancy in the system (multiple/secondary pumps) can help to avoid problems when maintenance and repairs are needed on the primary system.

When cleaning a sump pump, dirt, gravel, sand, and other debris should be removed to increase efficiency and extend the life of the pump. These obstructions can also decrease the pump's ability to drain the sump and can allow the sump to overflow. The check valve can also jam from the debris. Examine the discharge line opening, when applicable, to ensure there are no obstructions in the line. Even a partially obstructed discharge line can force a sump pump to work harder and increase its chance of overheating and failure.

Float switches are used to automatically turn the sump pump on when water rises to a preset level. Float switches must be clear of any obstructions within the sump. A float guard can be used to prevent the float switch from accidentally resting on the pump housing and remaining on. As mechanical float switches can wear out, they should be periodically tested by actuating them manually to assure that they continue to move freely and that the switch contacts are opening and closing properly.