Say goodbye to fluctuating constant water pressure ! 4 core scenarios + troubleshooting flowchart, easily applicable for maintenance personnel.

In constant pressure water supply systems, unstable water pressure is a persistent problem—the water flow weakens during peak usage times, water pressure spikes at night, and the daily water flow fluctuates, affecting not only the user experience but also accelerating the aging of pumps and frequency converters, increasing maintenance costs. Many industry professionals spend a lot of time troubleshooting but can’t find the root cause. In fact, most problems are concentrated in four main modules: signals, control, equipment, and piping. Today, we’ve compiled a highly practical troubleshooting guide, including corresponding solutions for different scenarios and practical techniques to help you quickly solve water pressure problems!

I. Let’s clarify the core logic behind unstable water pressure (see diagram below).

The core of a stable constant pressure water supply system is the closed-loop operation of “setting pressure → signal acquisition → control output → equipment execution”. A problem in any link will lead to water pressure imbalance.

Signal end: Pressure sensor “transmitting incorrect signals” (malfunction, improper installation);

Control end: Inverter/PID “sent wrong command” (parameter misalignment);

Equipment side: Water pumps/valves are not working properly (wear, internal leakage);

Pipeline end: “Poor pipeline transport” (blockage, air intake, leakage).

II. Four High-Frequency Scenarios: Identify and Quickly Resolve Them

1.Water pressure drops sharply during peak water usage periods (normal during off-peak periods).

Core reason: Water supply capacity cannot keep up with demand, or pipeline transportation is blocked;

Practical solutions:

① Check the water pump operating data. When the current is close to the rated value, add a water pump in parallel or replace it with a larger flow model;

② Disassemble and clean the front-end filter of the pipeline network to remove rust, impurities and other blockages;

③ Adjust the lower limit frequency of the frequency converter to 25-30Hz to avoid frequent start-stop of the equipment at low flow rates.

2.Frequent and irregular fluctuations in water pressure.

Core cause: Signal distortion or “overreaction” of control parameters;

Practical solution:

① Use an instrument to test the pressure sensor (normal output 4-20mA), replace it if damaged, and avoid the turbulent area at the water pump outlet when installing it;

② Optimize PID parameters: adjust the proportional gain (P) to 1.5-3.0, and set the integral time (I) to 60-120s to reduce overshoot oscillation;

③ Open the air vent valve at the end of the pipeline, or install an automatic air venting device to remove the air trapped in the pipe.

3.Higher water pressure at night/during periods of low water usage

Core cause: The hibernation function is not enabled, or water hammer is caused by internal leakage of the check valve;

Practical solution:

① Turn on the inverter’s sleep mode and set the sleep pressure to be 0.05-0.1MPa higher than the working pressure. Once the pressure is reached, the equipment will go into sleep mode to save energy;

② Adjust the set pressure according to actual needs (0.3-0.4MPa is sufficient for domestic water supply);

③ Check the sealing performance of the check valve. Replace it if there is an internal leak to prevent water backflow from causing abnormal pressure.

4.Sudden instability during operation (accompanied by abnormal equipment noise)

Core cause: Water pump failure or abnormal power supply/control equipment;

Practical solution:

① Disassemble and inspect the water pump, check if the impeller is worn or cavitated, replace damaged parts, and check the sealing of the suction pipe to prevent air from entering;

② Restart the frequency converter, check the fault codes (overcurrent, overload, etc.), and repair the circuit or module accordingly;

③ Install a voltage regulator to stabilize the power supply voltage and avoid voltage fluctuations affecting the equipment output.

III. Three routine maintenance habits: reducing failures at the source

1.Calibrate the pressure sensor every 3-6 months, and clean the probe surface of oil and scale to ensure accurate signal.

2.Monthly inspection of water pumps: listen for abnormal operating noises, check lubricating oil levels, replace worn seals, and extend equipment life;

3.Adjust pressure settings seasonally: Increase the pressure by 0.05 MPa during winter when water consumption is high, and decrease it appropriately during the rainy/off-season. Clean the pipe network filter regularly.

In fact, unstable water pressure in a constant pressure water supply system doesn’t require blind troubleshooting. Verify each step in the order of “signal → control → equipment → pipeline,” and then combine this with a solution tailored to the specific scenario. Most problems can be resolved within an hour. If you encounter any complex issues, feel free to leave your equipment model and operating parameters in the comments section so we can discuss solutions together!