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4” Submersible Pumps and Motors FAQs


What is a 4” submersible pump?

A 4” submersible pump is a well pump that utilizes a series of impellers and diffusers to build pressure and send water from the pumps inlet to a water system. These pumps are primarily used in deep wells, and are capable of overcoming great vertical heights while maintaining a 40/60 psi differential in a home.

What is a 4” submersible motor?

This is the motor that attaches to the bottom of the pump end. A motor’s horsepower must be match to that of the pump it is powering and supplied voltage/phase must be considered when making a selection.

What HP pump do I need?

The horsepower required will depend on the total vertical lift, pressure required, and the flow desired. A higher horsepower pump will give you a variation of higher flow and/or pressure.

Do I need a control box?

A 3-wire motor will require a control box. The control box for a 3-wire motor contains the starting components for the motor.

What’s the difference between 2- and 3-wire motors?

The main difference between a 2- and 3-wire motor is the location of the capacitors, or starting components. In a 2-wire system, these are located in the motor itself. In a 3-wire system, they are located externally in a control box. People often opt for the 3-wire motors because if anything happens to the starting components they can be easily replaced, whereas in a 2-wire system the same problem would require the whole motor be replaced. Click here for RCWorst YouTube video: 2 Wire Vs 3 Wire Well Pump Motors

Do I need to use check valves in my drop pipe?

Yes, check valves prevent water from flowing back down through your pipes into the well. Typically there is a built in check valve on the pump, and it is recommended a check valve be installed every 100 feet to distribute the weight on each valve.

What controls do I need for my motor?

If you have a 2-wire motor, the starting components are built into the motor. If you have a 3-wire motor, you will need an external control box that houses the starting components. You must make sure the horsepower and voltage of the motor and control box match.

How do I control my pump according to my well’s yield?

There are a few ways to control your pump. The first is to have it sized properly prior to installation. If the pump is already installed and the well yield has dropped, you can put a dole valve on the drop pipe that will limit the pump’s output to the yield of your well. Another option would be to install a pump saving device. This is a device that monitors incoming power, and will shut the pump off if it senses it is not moving the proper amount of water.

How deep should I set my pump?

Typically pumps are installed 10’ off the bottom of the well. If there is sand or abrasives in the well you will want to set it ~20’ off the bottom.

Click below to see RC Worst YouTube videos:

7 Things Every Well Pump Owner Should Know

Troubleshooting Water Well Pumps: Introduction

Troubleshoot: Water Well Pump Starts too Often (Rapid Cycling)

Troubleshoot: Water Well Pump Does Not Start

Troubleshoot: Water Well Pump Won't Shut Off

Troubleshooting 4" Submersible Motor: Insulation & Windings Resistance