The Ultimate Guide to Well Pump Pressure Switches: How They Work, Troubleshooting, and More

A well pump pressure switch is a vital component of any water system relying on a well. It is the control device, automatically activating and deactivating the pump to maintain consistent water pressure.

This article provides a detailed look into how these switches function, covering the internal mechanisms and electrical connections involved. We will explain the water pressure cycle, the role of the pressure tank, and typical pressure settings. You will also learn to identify common problems, such as pump malfunctions, and how to troubleshoot issues using a step-by-step approach.

What is a Well Water Pump Pressure Switch

A well water pump pressure switch is a mechanical device that controls the operation of a well pump based on the water pressure within a water system. It serves as the primary control mechanism, automatically activating and deactivating the pump to maintain consistent water pressure.

The pressure switch’s main function is to monitor the water pressure in the system and activate the pump when the pressure drops to a pre-set low level (cut-in pressure) and deactivates the pump when the pressure reaches a pre-set high level (cut-off pressure).

How a Well Water Pressure Switch Works

The pressure switch employs a combination of mechanical and electrical components to regulate a well pump. The main components are a diaphragm, a spring, and electrical contacts.

Internal Mechanism

The core of the pressure switch features a diaphragm, typically made of rubber or a similar flexible material. This diaphragm is directly exposed to the water pressure within the plumbing system. Changes in water pressure cause the diaphragm to move, exerting force on a spring-loaded mechanism. The spring provides resistance against the water pressure, and the level of resistance is set by an adjustment nut or screw.

The movement of the diaphragm and spring then actuates a set of electrical contacts. These contacts are responsible for completing the electrical circuit to the well pump. When the diaphragm moves due to low pressure, the contacts close, allowing electricity to flow and power the pump. Conversely, when the pressure increases, the diaphragm moves in the opposite direction, causing the contacts to open, cutting off power to the pump.

The Water Pressure Cycle

The pressure switch operates within a defined pressure range. This range is delimited by two critical pressure points: the cut-in pressure and the cut-off pressure. When water pressure within the system drops to the cut-in point, the pressure switch closes the electrical contacts, which activates the well pump. The pump then begins to replenish water into the system, increasing the pressure.

As the water pressure rises to the cut-off point, the diaphragm pushes against the spring, causing the electrical contacts to open and deactivating the pump. This cycle maintains the water pressure within a usable range, providing a consistent flow. The difference between cut-in and cut-off pressures is often referred to as the pressure differential.

Interaction with the Pressure Tank

The pressure switch doesn’t work alone; it is often paired with a pressure tank. The pressure tank serves as a reservoir, storing a volume of pressurized water and reducing the frequency with which the pump needs to cycle on and off.

The pressure tank contains a compressed air bladder that absorbs changes in pressure. When water is drawn from the system, the pressure in the tank decreases, and when the pressure drops to the cut-in level, the pressure switch activates the pump. The pump then refills the pressure tank to the cut-off level, creating a reserve of pressurized water that can be used before the pump cycles on again. The pressure switch, in this regard, serves as an important element in conjunction with the pressure tank to achieve an efficient and stable water supply.

Typical cut-in/cut-off pressure combinations

Note: These values can vary slightly based on manufacturer specifications.

Location of the Pressure Switch in Your System

The pressure switch is typically located at the pressure tank or at the tank tee, which is a fitting where the pressure tank connects to the water line. This placement allows the switch to accurately monitor the water pressure within the system. It is essential that the pressure switch is mounted to a location that is accessible, allowing for future maintenance or replacement.

The pressure switch is connected to several other crucial components in the system. A pipe from the well pump enters the pressure tank, and another pipe directs water to the household supply. The pressure gauge is often installed nearby, allowing for visual monitoring of the pressure. All of these parts work as a system to ensure a constant water supply to the building.

Symptoms of Well Pump Pressure Switch Problems

• Pump not turning on at all: If the pump fails to activate when water is being used, or when the pressure in the system is low, it could be due to a faulty pressure switch. The electrical contacts within the switch may be damaged or corroded, preventing the completion of the electrical circuit to the pump.
• Pump not turning off or running continuously: When the pump continues to run even when the desired pressure is reached, it indicates that the pressure switch is not deactivating the pump. This could result from a damaged diaphragm, which fails to properly signal the switch to cut off the pump’s power, or stuck electrical contacts.
• Rapid pump cycling (frequent on/off): Rapid cycling is when the pump turns on and off frequently. This issue often means there is a problem with either the pressure switch or the pressure tank. It can also indicate a leak in the system. A malfunctioning pressure switch might not accurately sense the pressure changes, leading to frequent pump activation and deactivation, which can cause damage and increase energy consumption.
• Fluctuating or low water pressure: Inconsistent water pressure or a sudden decrease in pressure can indicate a problem with the pressure switch’s ability to regulate the pump’s operation. This can be caused by a malfunctioning pressure switch or by an incorrectly set cut-in/cut-off pressure range.

Step-by-Step Troubleshooting Guide

Step 1: Checking the electrical supply

Begin by verifying that the electrical power supply to the pump and switch is functioning properly. Check the circuit breaker associated with the well pump, making sure that it is not tripped. If tripped, reset it. Also, inspect the fuses in the electrical panel related to the well pump, replacing any blown fuses.

Step 2: Examining the pressure gauge

Compare the gauge reading with the expected cut-in and cut-off pressures. If the gauge appears to be inaccurate or is fluctuating erratically, it may need to be replaced. The pressure gauge is a vital tool in troubleshooting and should be inspected before proceeding to other steps.

Step 3: Identifying potential leaks

Leaks in the water system can cause the pump to cycle on and off more frequently than normal or not at all, mimicking issues with the pressure switch. Carefully examine all pipes, fittings, and connections for any signs of leaks. This step is critical since water loss can lead to pressure fluctuations, which can cause the pump to operate erratically. Even small leaks can affect the performance of the pump and the pressure switch.

Step 4: Inspecting the pressure switch

Physically inspect the pressure switch itself for any signs of damage. Look for cracks, corrosion, or water damage. Check the electrical connections to ensure they are tight and free from corrosion. If you find physical damage to the pressure switch, it may need to be replaced. Verify the switch’s condition carefully, making note of any abnormalities.

Step 5: Testing the switch with a multimeter

A multimeter is a useful tool for determining if the pressure switch is working correctly. Set the multimeter to measure continuity. With the pump off, place the multimeter’s probes on the switch’s electrical contacts. When pressure in the system is below the cut-in pressure, the multimeter should indicate continuity, confirming that the electrical circuit is complete. When the water pressure is above the cut-off, the multimeter should indicate no continuity. If the meter gives different readings, the switch may have failed or be defective and needs to be replaced.

Step 6: Tapping the switch and gauge

Sometimes, debris or sediment can accumulate inside the pressure switch or pressure gauge, causing inaccurate readings. Gently tap the switch and gauge with a light object, such as the handle of a screwdriver. This may dislodge debris that could be preventing the pressure switch or gauge from functioning correctly. If this step resolves the issue temporarily, further inspection or cleaning may be needed.

Can you run a well pump without a pressure switch?

No, you should not run a well pump without a pressure switch. The pressure switch is essential for regulating the pump’s operation based on water pressure. Without it, the pump would run continuously, potentially causing damage, overheating, and wasting energy. It is a safety mechanism for the well system.

Do well pumps have a built-in pressure switch?

Most submersible well pumps do not have a built-in pressure switch. The pressure switch is typically a separate component installed on the pressure tank or the piping system. However, some jet pumps may incorporate a pressure switch into the pump housing.