Sprinkler Pump Buying Guide

Keep your lawn healthy and thriving without depleting water resources by utilizing a sprinkler pump. Sprinkler pumps are designed to provide a steady flow of water from a source like a pond or cistern. When it comes to something as vital as choosing your irrigation system, Ferguson Home is here to help. Let us guide you through the proper way to select the right sprinkler pump for your needs.

How to Size Your Sprinkler Pump

Before you look at a single pump, you must design your sprinkler system. The pump must be sized to meet the demands of the finished system. Once your layout is complete, you can confidently calculate the metrics below, ensuring your pump operates efficiently without being undersized (leading to poor coverage) or oversized (which can blow out sprinkler heads or cause sporadic spray patterns).

We’ve compiled a comprehensive, step-by-step process for gathering the necessary data to select your sprinkler irrigation pump, ensuring we can provide you with a solution tailored to the complexity of your project.

Step 1: Calculate Your System's Total GPM and Required PSI

First, determine the core operational needs of your pump. All sprinkler heads are rated for a specific flow (GPM) and pressure (PSI).

• PSI (Pressure): The required PSI typically remains the same across all zones and is dictated by the specifications of your sprinkler heads.
• GPM (Flow): To find the total system flow required, add up the GPM requirements for all the sprinkler heads that will run simultaneously in your largest zone.

Example: If you have 10 sprinkler heads, and each is rated at 4 GPM at 40 PSI, your system's requirement is 40 GPM at 40 PSI.

We will then use this benchmark (e.g., 40 GPM at 40 PSI) to size the pump as closely as possible to your system's exact needs.

Step 2: Determine Your Total Head (Height of Pumping)

"Head" refers to the elevation and pressure the sprinkler pump must overcome.

1.   Suction Head (How High You Pull): Measure the distance from the surface of the water source straight up to the centerline of the pump. This rise in elevation should ideally be no more than 5 feet high and must not exceed 25 feet at sea level. Pumps find it much harder to pull water up than to push it out.

2.   Discharge Head (How High You Push): This is the lift required to push the water from the pump to the highest point in your irrigation system. This maximum limit depends on the pump (e.g., 50, 80, or 120 feet).

3.   Total Head: Your total head lift is the suction head added to the discharge head (Suction Head + Discharge Head).

Step 3: Account for Distance and Pipe Diameter

Friction loss caused by the horizontal distance the water travels can significantly affect water pressure. To maintain optimal flow and pressure, you may need to increase your discharge pipe diameter:

As a general rule, increase the pipe diameter by one size for every 300 feet of horizontal pumping distance. A friction loss chart is recommended for more complex designs involving many fittings.

Step 4: Confirm Power Requirements

Pumps run on more than good intentions. Ensure your electrical supply matches the pump's specifications.

• Most smaller pumps are dual voltage (115V or 230V).
• Larger units (2-1/2 HP, 3 HP, and above) are often rated for 230V or higher 3-phase power.
• If no electricity is available, we can guide you to a suitable gas-powered alternative.

Step 5: Understand the Priming Method

While most modern irrigation pumps are self-priming, some require a manual prime upon initial installation.

• Priming involves filling the pump housing and priming port with water to force out any air.
• Any air pockets can cause the pump to become air locked, preventing proper operation.
• By installing a check or foot valve on the suction pipe, you ensure the pump stays primed if suction is never lost.

Step 6: Select the Ideal Location

The location is critical for pump performance and longevity:

1.   Proximity to Source: Install the pump as close to the water source as possible, due to the 25-foot suction head limitation.

2. Protection and Ventilation: Locate your pump in a cool, dry area protected from direct sunlight and rain. It must also be well-ventilated to prevent overheating.

Having the above information will help you find the perfect, right-sized sprinkler pump for your system. Reach out to our Ferguson experts for additional product support and expertise.