If you need a sprinkler pump for your irrigation system, which sprinkler/irrigation pump do you need? A self priming above ground pump or a submersible in a well?
This post will help you gather the information you need to choose which is the right one for your needs. If you have a new installation this post can provide you with the information needed to get the right pump for the job. If you have an existing sprinkler system and pump, this information will let you know if you have the right pump for your application.
A vast majority of sprinkler systems have undersized pumps that under supply the correct flow and pressures and give the illusion of working properly by providing the bare minimum of flow and pressure if at all. The timer may be the brains of the sprinkler system but your pump is the heart and a strong one allows the sprinkler system to operate at peak efficiencies providing a beautiful landscape for years to come.
The information provided is assuming the user has a basic knowledge of irrigation, plumbing, and electrical and is intended for residential and small commercial sites. This information is basic “rule of thumb” or the minimum or maximum requirements to size a pump. Should you feel uncomfortable with this information and would prefer more exacting details, please contact a local pump specialist.
New Pump Installation
Do you need an above ground pump or a deep well and a submersible pump?
If you are in an area where shallow wells are easy to do and provide plenty of water or your property is on a lake or some other water source then an above ground pump is the cost effective option for you. Otherwise a deep well and submersible pump will be required.
Note: A shallow well is a well with a water depth of 25 feet or less. A deep well has a water depth of 25 feet or more and usually consist of a 4 inch casing or larger drilled into the ground from a hundred feet to several hundred feet deep.
Replace Existing Pump
Does your existing pump give you the performance it should or that you should have?
If it is about to fail or has failed, you may want to replace the pump with the same model if it has worked well for you. However, many pumps are undersized from day one providing less than adequate water flows and pressures giving the illusion of proper water application. Use the sizing information provided to determine if replacing the pump with the same model will work for you or if there is another more efficient model for you.
Locate The Pump For Your Needs
With this information, you can now contact your area pump or irrigation supply house and ask which one they have to suit your needs. By doing so your using a pump that is locally available which means parts are readily available if repairs are ever needed, the pump is easily replaceable if needed, and you are using one that will be familiar with local pump service people. There are many manufacturers, choices, applications, and your geographic location that can determine which one is best for you. Area pump supply houses have already learned over the years which one will give you what you need and by knowing this information will stock only a few types to choose from making the selection process much easier.
You may have to choose from 2 to 3 pumps that are close to your requirements. Which one do you choose?
Look at these three options:
1. A pump at 10% to 20% more GPM and pressure than you need.
2. A pump that pumps close to or exactly what you need.
3. A pump that is just under your GPM and pressure requirements.
If possible resist the urge to cut corners to save money “today” by getting option two or three. Once you install and begin using the pump it begins to wear out reducing its water flow and PSI capabilities. Within a few short years its performing well below your expectations, your landscaping is suffering, and now your wishing you had the better quality one. Now you have the added expense of replacing the pump with the same one and begin the process all over again or you put the better pump in. By getting a pump that pumps a little more water and pressure you can always throttle back on GPM and pressure and as the pump wears over the years you will have extra performance to use when needed giving you years of extra use and much less worry and aggravation. But if the budget is tight then option number 2 will be your best choice.
Be aware that horsepower may be misleading. Sometimes going bigger doesn’t always work. Pumps come in three designs… low head, medium head, and high head. A low head one will pump a lot of water at very little pressure like a pool pump. A medium head one will pump a little less water and little more pressure. A high head one will pump even less water but at much higher pressures as needed for irrigation systems. All three design types could have the same horsepower but provide three totally different performances. On more than one occasion we have switched out 2 HP pumps with 11/2 HP multi stage pumps to get better flow and pressures. Or it may take a 2 HP centrifugal pump to do what a 1 HP submersible was flowing. Sometimes it’s the application that dictates pump size and design type.
Do you get a cast iron or all plastic pump? Plastic types are usually a lot cheaper than cast iron types and will perform about the same. But from our experience plastic pumps either centrifugal or submersible have a much shorter life so we use cast iron pumps for longevity and fewer problems.
New Or Existing Centrifugal Pump Sizing Information
Here are some hard facts you need to know when sizing/picking an above ground pump of any kind and its location. For best performances the pump must be located as close to the water supply as possible. The suction side and pipe plumbing of the pump is the key to operating at peak performance.
At sea level we deal with 14.7 pounds of gravity. When a pump is turned on, it begins to remove the atmosphere inside the suction pipe and as it does, the 14.7 pounds of gravity pressure pushing down on the surrounding water begins pushes water up replacing the atmosphere being removed in the suction pipe. But there is a limit to how far the water will go up the pipe. For every 2.31 feet (roughly 2 feet and 3 3/4 inches), you lose 1 PSI of gravity force and that limit is only 33.9 feet mathematically but due to pipe friction losses and pump inefficiencies the rule of thumb is 25 feet is the maximum any pump will lift water regardless of any other factors. Plus, for every 5 feet of “total suction lift” the pump has to deal with, it loses about 15% to 20% of its discharge GPM.
Another factor to keep in mind is that for every 2000 feet of elevation, you will lose 1 PSI of the 14.7 PSI gravity force. Over 25 feet of lift and they will pump very little if any water and may begin to cavitate. Cavitation is a process where the water is under enough vacuum force to literally separate itself forming small bubbles that explode in it making the pump sound like its full of rocks. The pump will never prime or pump water and if left to run long enough, the cavitation can damage the internal parts of the pump. This calculation applies to all centrifugal pumps no matter if the water source is a shallow well, lake, or other water source.
So, the closer we get and keep the pump to water, the more gravity force we have and can pump more water and pressure. This is why the suction side of any pump is more important than the discharge side. We can virtually overcome any problem on the discharge side of the pump by sizing the pump accordingly.
Also, gallons per minute (GPM) determines pipe size… not pump taps. Its very possible for your pump to come with much smaller or larger suction and discharge tap sizes than the pipe needed to meet its GPM flow. Simply plumb out of those fittings but immediately and within a couple of feet expand or reduce to the pipe size that meets or exceeds the GPM flow rate. We recommend using galvanize, brass, or copper fittings out of the pump using nipples and bell reducers until you meet your pipe size then covert over to PVC SCH 40 pipe for all pipe exposed to the elements and once underground convert to standard PVC or poly pipes.
When pulling water from a lake, shallow well, or other water source you will need a self priming pump of some sort. For systems requiring low flows such as 5 GPM to about 15 GPM, jet pumps are a good pick. They provide a steady flow and good pressure. However, most sprinkler systems usually use well above these flow rates. Our next pick will be will be self priming centrifugal pumps. They have large pump bodies to hold there priming water and can pump from 15 GPM to about 45 GPM depending on horse power (3/4HP to 2 1/2HP) and site conditions. If higher pressures are needed then multi-stage pumps are a good option within the same horsepower range. These pumps use two or more impellers to increase flow and pressure providing 20 to 45 GPM with pressures up to 65 PSI if not more. 3 HP and 5 HP can provide from 45 GPM to 80 GPM plus. Once you get into higher flows and/or pressures we would strongly recommend contacting a pump specialist to assist you in sizing a pump because you will probably need a custom sized pump for your needs.
- Jet Pumps
- Self Priming Centrifugal Pumps
- Multi Stage Pumps
- 3 HP and 5 HP Pumps
What To Look For When Buying A Lawn Sprinkler Pump?
When choosing a lawn sprinkler pump you need to understand that all sprinkler pumps are not created equal. There are many styles and benefits when it comes to owning certain sprinkler pumps and figuring out the difference between one lawn sprinkler pump and another sprinkler pump can get quite confusing but lucky for you that you came across this article that will give you some basic and priceless information about some of these sprinkler pumps.
When you are looking for a water pump for irrigation you need to keep in mine that there are different brands that carries lawn sprinkler pumps and some brands are better than others. Owning a stainless steel lawn sprinkler pump has a huge benefit and that is it will withstand corrosion and the durability is usually good when it comes to a stainless steel sprinkler pump. Another thing you want to look out for when choosing a sprinkler pump is motor size and speed. Obviously having a better motor in a sprinkler pump will allow it to pump out water at a faster rate and the life span of the pump will be much better than with a lower quality motor.
Some lawn pumps are designed more for just lawns while others are designed to sprinkle small lakes, ponds, rivers and such. The benefits to having a sprinkler pump with a fast and strong moving motor are great because if you are trying to sprinkle a small pond than a fast and stronger motor will do the job fine but if you just want to water a basic lawn than a simple and basic sprinkler with an average motor will get the job done. Now there are a few different types of them, for instance there are pumps that are installed above ground and then there are pumps that are installed underwater and then there are pumps that are installed below the ground but has a motor above ground.
What pump you end up getting just make sure that it is a durable one and will last for quite awhile and don’t sacrifice quality for price.