Mechanical seals and Pumps

What Causes Short Cycling of Water Pumps

Have you noticed your water pump turning on and off more frequently than usual? This issue, known as short cycling, can be frustrating and potentially damaging to your pump. In this blog post, we’ll explore the common causes of water pump short cycling and provide you with practical solutions to help you resolve this problem and extend your pump’s lifespan. 645c6ac7c3404

What Is Short Cycling in Water Pumps

Short cycling is when a water pump turns on and off rapidly, more frequently than normal. This can lead to increased wear and tear on the pump.

Common Causes of water Pump Short Cycling

Insufficient Air Charge in the Pressure Tank

When a pressure tank loses its air charge, it can cause the water pump to short cycle. The air charge in the tank acts as a buffer, allowing the pump to run for longer periods before shutting off. Without sufficient air, the pump will turn on and off more frequently, leading to increased wear and tear on the system.

To resolve this issue, check the air pressure in the tank using a tire pressure gauge. The air pressure should be set to 2 PSI below the pump’s cut-in pressure. If the air pressure is low, use an air compressor to add air to the tank until the proper pressure is reached.

Too Much Air in the Pressure Tank

Conversely, having too much air in the pressure tank can also cause short cycling. When there is excess air, the tank’s water capacity is reduced, causing the pump to turn on more often to maintain water pressure.

To fix this problem, drain some of the air from the tank using the air valve located at the top of the tank. Continue to release air until the proper pressure is achieved, as mentioned in the previous section.

Faulty Pressure Switch

A malfunctioning pressure switch can lead to short cycling by sending incorrect signals to the pump. The pressure switch is responsible for turning the pump on and off based on the water pressure in the system. If the switch is not working properly, it may cause the pump to turn on and off too frequently.

To diagnose a faulty pressure switch, observe the pressure gauge while the pump is running. If the gauge fluctuates rapidly or does not reach the proper cut-off pressure, the switch may need to be adjusted or replaced.

Blocked Water Supply Lines or Filters

Obstructions in the water supply lines or filters can restrict water flow, causing the pump to work harder and short cycle. Blockages can occur due to accumulated debris, mineral buildup, or damaged pipes.

Inspect the water supply lines and filters for any visible signs of blockage. Clean or replace filters as needed, and flush the lines to remove any debris. If the problem persists, a professional plumber may be required to assess and repair the issue.

Irrigation Zones Are Too Small

In irrigation systems, short cycling can occur when the zones are too small, causing the pump to turn on and off frequently to maintain water pressure. This issue is more common in systems with multiple zones that have varying water demands.

To alleviate this problem, consider combining smaller zones to create larger ones, or install a larger pressure tank to accommodate the increased demand. Adjusting the irrigation schedule to allow for longer run times and fewer cycles can also help reduce short cycling.

Insufficient Water Supply

If the water supply to the pump is inadequate, it can cause the pump to short cycle as it struggles to maintain proper water pressure. This can happen when the well or water source is running low, or if there are leaks in the supply lines.

To address insufficient water supply, first check for any visible leaks in the system and repair them as needed. If the water source is the issue, consider deepening the well or exploring alternative water sources. In some cases, installing a larger pressure tank or a constant pressure system may help mitigate the effects of an insufficient water supply.

Undersized Pressure Tank or Incorrect Pressure Settings

An undersized pressure tank or incorrect pressure settings can cause the pump to short cycle by not providing adequate water storage or pressure control. The pressure tank should be sized appropriately for the system’s water demand and the pump’s flow rate.

To determine if the pressure tank is adequately sized, consult with a professional plumber or refer to the manufacturer’s specifications. Ensure that the pressure settings on the tank and pressure switch are adjusted correctly to match the pump’s cut-in and cut-out pressures. If necessary, replace the pressure tank with a larger one to accommodate the system’s water demand.

In conclusion

Short cycling of water pumps can be caused by various factors, including incorrect pressure tank settings, leaks, and clogged filters. Identifying and addressing the root cause is essential for optimal pump performance and longevity. Contact a professional plumber to diagnose and resolve any issues with your water pump system.


Todd is the manager of Cowseal mechanical seal manufacturer. Cowseal located in China with over 20 years of experience in the mechanical seal and pump industry. They offer a wide range of high-quality mechanical seals and are committed to providing reliable and cost-effective solutions for their customers.

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