Are you wondering what size sump pump you need for your basement? Do you know how to calculate Sump Pump Size Needed for Primary Sump Pump?
Why Is Sump Pump Size Calculation Important?
Sump Pump Size Needed Calculation is important because it helps you determine what size of sump pump is required for your basement.
There are many factors that impact the size. We will discuss each of the following.
Here’s the detail on each of the above factors.
How Does Type Of Soil Make A Difference In The Size Of Sump Pump Needed?
Clay soil requires a smaller sump pump than sand or top soil. If clay is found around the house, a flow of 8 gallons of water per minute per 1000 square feet of house is estimated. Clay is impermeable meaning it holds water better. If sand is found around the house, a flow of 14 gallons of water per minute per 1000 square feet of house is expected. Top soil flow is somewhere between 8 and 14 gallons per 1000 square feet of house. Sand and soil are permeable.
How Does Elevation Of The House Impact Rate Of Water Flow Into The Sump Pump Pit?
A house on flat land or in a lower position than surrounding land requires a larger sump pump. Water flow into a drainage system is decreased by house elevation. If the house sits higher than the ground around, less water will seep into the drainage system at a slower rate. Regardless of how high the house sits, the more slopped the soil is around the house downward toward the yard, the slower the flow of water into the sump pit. The flow of water is also decreased by a layer of clay like soil under the top soil.
How Does Square Footage Of House And Roof Impact The Size Of Sump Pump Required?
The larger the house and the steeper the room, the larger the sump pump must be.
The house with a larger foot print will cover a larger area for water seepage into the drainage system. A steeper roof will also increase the speed at which the water flows and the area from which water flows.
How Does The Sump Pit Size Impact The Size Of Sump Pump Needed?
Since it is best to keep the water below the drainage system pipe that comes into the pit, measure the distance in inches to the bottom of the drainage pipe; then monitor how many seconds it takes before the pit water reaches the bottom of the drainage pipe. This will indicate the pumping capability needed.
For example, if it takes 15 seconds to fill the pit up to the drainage pipe which is 15 inches from the bottom of the pit, the sump pump will require a pumping capability of 60 gallons per minute.
How Does The Vertical Height Of The Discharge System Affect The Sump Pump Needed?
The vertical height of the discharge system, also known as the lift height, is the height of the discharge piping from the location when the discharge piping screws into the sump pump discharge port to the highest vertical point of the discharge pipe before the piping runs horizontally.
Sump pump manufacturers advertise their sump pumps by gallons pumped per hour per height of the vertical lift. For example if the vertical lift was 9 feet and the pump needed to pump 60 gallons per minute, it would be necessary to install a sump pump that pumps at least 60 gallons per minute at a ten foot lift height.
How Do Fittings Impact The Size Of Sump Pump Needed?
Fittings cause resistance to the water flow and thus require more pumping capability. Fittings include such things as check valves and elbows.
Here’s the impact of fittings.
Here’s how we apply the impact of fittings.
How Does The Horizontal Piping Impact Water Flow?
Here’s what we can learn from the manufacturers manuals.
How Does Rain Storm Intensity And Frequency Affect Sump Pump Size Required?
The size of sump pump required needs to be calculated based on four rainstorm factors.
Heavy, lengthy rainstorms and flooding are becoming more prevalent; therefore it is necessary to plan for the worst case scenario. Only a 1/2, 3/4 and 1 HP cast iron pump can keep up with lengthy, heavy rain storms.
Installing a heavy duty sump pump to handle heavy rainstorms has its challenges if there are many small rainstorms.
A heavy duty pump will be too big for such storms; it will empty the sump pit too quickly because the ‘on’ ‘off’ point for the float switch is preset by the manufacturer. This will cause additional wear and tear to the pump motor. One solution for this situation is to purchase a non-automatic sump pump such as the Zoeller N98 and buy a variable level float switch will allow you to set a greater distance between the ‘on’ and ‘off’ position.
Conclusion
To size a sump pump correctly, it is very important to know the area surrounding the home. Inclination and soil type can increase or decrease the flow of water round the house. Slopping away from the house and clay soil are best.
The size and slope of the roof impact the amount of rain and its flow around the foundation. Large sloping roofs cause a real high impact flow.
The size of the sump basin determines how much water can accumulate in the basin before it must be pumped out. A twenty-four inch diameter pit holds twice as much water.
Elbows and vertical height cause friction which slows the flow of water upward and away from the house. The less elbows and vertical height, the less friction there is to slow the flow of the water up the discharge pipe and to its predetermined location.
Manufacturers provide Pump Performance charts to help the home owner choose the right sized sump pump. Making use of the charts is important when buying a sump pump.
Considering all of the facts presented above, will result in the purchase of a right sized sump pump.
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