Application Guide of Pressure Sensors in the Air Conditioning Industry: Key Technologies to Improve System Efficiency and Reliability

As summer temperatures rise, demand for air conditioning increases sharply. Whether for residential units, split systems, or central air conditioning, pressure sensors play an indispensable role. These sensors are widely used in refrigeration equipment to help monitor system operating conditions, achieve minimized energy consumption, and enable automated control.

The Role and Importance of Pressure Sensors in the Air Conditioning Industry

The core of an air conditioning system is the refrigeration cycle, which involves components such as the compressor, condenser, expansion valve, and evaporator. As the refrigerant circulates through these components, high-pressure and low-pressure changes occur. Pressure sensors are the key devices used to monitor these pressures. They continuously collect pressure signals from the refrigerant and feed them back to the control system, which then adjusts compressor operation, fan speed, or valve opening accordingly.

In actual operation, excessively high pressure may cause system overload or pipe rupture, while abnormally low pressure often indicates insufficient refrigerant or blockages. Pressure sensors can promptly detect these abnormalities and trigger protective mechanisms to prevent equipment damage. This not only extends the service life of air conditioners but also improves energy efficiency. According to industry data, air conditioning systems equipped with high-precision pressure sensors can reduce energy consumption by 10–20%. In addition, in inverter air conditioners, sensors support fine control, providing a more comfortable indoor environment.

HVAC system acting up? Take a look at its superheat measurements ...

Main Advantages of Pressure Sensors

Pressure sensors offer significant advantages in the air conditioning industry. First is real-time monitoring capability. They convert pressure changes into electrical signals, enabling systems to automatically optimize operation and reduce manual intervention. Second is high safety. By setting high- and low-pressure thresholds, sensors prevent compressors from starting under unfavorable conditions, protecting critical components.

Third is remarkable energy-saving performance. Sensor data is used to calculate energy efficiency ratios (EER or COP), guiding systems to operate within optimal pressure ranges and reducing power consumption. Fourth is strong compatibility. Modern pressure sensors support multiple output modes, making them easy to integrate into smart home systems or building management systems. Long-term use also provides data logs that facilitate fault diagnosis and preventive maintenance.

Types and Characteristics of Pressure Sensors in Air Conditioning Systems

Air conditioning pressure sensors are mainly divided into high-pressure sensors and low-pressure sensors based on installation location and measurement range. High-pressure sensors are typically installed on the compressor discharge side or at the condenser inlet, monitoring high-side pressure (commonly with ranges of 0–5 MPa). Low-pressure sensors are installed on the suction side or at the evaporator outlet, monitoring low-side pressure (with ranges of approximately −0.1 to 2 MPa).

There are various signal output options, including current output (4–20 mA, strong anti-interference capability, suitable for long-distance transmission), voltage output (0–5 V or 0–10 V, fast response), and RS485 digital output (supporting the Modbus protocol for easy networking). These outputs can be directly connected to PLCs or air conditioning controllers to enable automation.

The sensing elements are typically based on ceramic or diffused silicon technology, offering corrosion resistance and vibration resistance, and are suitable for common refrigerants such as R410A and R32. Protection ratings usually reach IP65 or higher, ensuring reliable operation in humid or dusty environments.

Application Scenarios of Pressure Sensors

Pressure sensors are widely used across the air conditioning industry. In residential wall-mounted or floor-standing air conditioners, they are mainly used for compressor protection: low-pressure sensors detect refrigerant leakage, while high-pressure sensors prevent overheating.

In central air conditioning or multi-split systems, a larger number of sensors are used to support zoned control and inverter regulation. For example, in heat pump air conditioners, sensors monitor pressure changes during four-way valve switching to ensure smooth transitions between heating and cooling modes.

In automotive air conditioning systems, pressure sensors are integrated into refrigerant pipelines and work with the ECU to achieve precise control. Industrial refrigeration equipment, such as cold storage facilities, also relies on pressure sensors to maintain stable pressure conditions. In smart air conditioners, sensor data can be uploaded to the cloud to support remote diagnostics and energy consumption analysis.

Installation Methods and Connection Tips for Pressure Sensors

Proper installation is critical to ensuring sensor accuracy. Typically, high-pressure sensors are connected to the compressor discharge pipe, while low-pressure sensors are connected to the suction pipe. Common interfaces include M20×1.5 male threads, G1/4 female threads, and G1/2 male threads, selected according to pipeline specifications. Some models support customized interfaces to meet on-site requirements.

Installation steps include evacuating the refrigerant from the system, tightening the sensor (with torque controlled at 20–30 Nm to prevent leakage), and connecting the signal cable (shielded cables are recommended to reduce interference). After powering on, zero and full-scale calibration should be performed. Avoid vibration sources and high-temperature areas, and ensure the sensing element is in full contact with the medium.

For inverter air conditioners, sensors should be installed close to the compressor to ensure rapid response to pressure fluctuations.

Measurement Principles and Selection Recommendations for Pressure Sensors

Most pressure sensors operate based on the piezoresistive effect: pressure acts on the sensitive element, causing resistance changes that are converted into standard signals through amplification circuits. Typical measurement accuracy is ±0.5% FS, with response times in the millisecond range.

When selecting a sensor, consider factors such as measurement range (matching high- or low-pressure sides), output type (compatible with the controller), temperature resistance (−40°C to 125°C), and media compatibility. Priority should be given to reputable brands and products with certifications such as CE or RoHS. For limited budgets, current-output sensors are suitable for long-distance transmission, while digital sensors are advantageous for smart system upgrades.

Maintenance and Care of Pressure Sensors

Regular maintenance can extend sensor service life. Routine inspections should focus on interface sealing to prevent leaks. Clean the sensing probe every six months to prevent oil contamination. Calibration is typically required every one to two years, using standard pressure sources for verification.

Common faults include reading drift (possibly due to aging of the sensing element) or no output (often caused by wiring issues). During maintenance, avoid excessive tightening or mechanical impact. Store sensors in dry environments and take anti-static precautions.

How to Choose the Right Air Conditioning Pressure Sensor

When selecting a pressure sensor, evaluate the system type (fixed-speed or inverter), pressure range, and environmental conditions. Models with overpressure protection are recommended. Refer to user feedback and manufacturer technical support. Cost-effective sensors can significantly improve air conditioning reliability and energy efficiency.

Frequently Asked Questions (FAQ)

What symptoms indicate a faulty air conditioning pressure sensor?
Frequent compressor start-stop cycles, poor cooling performance, and error codes such as high-pressure protection alarms.

How are the ranges of high-pressure and low-pressure sensors distinguished?
High-pressure ranges are generally 3–5 MPa, while low-pressure ranges are typically 0.1–2 MPa, depending on the refrigerant type.

Can pressure sensors be replaced by users themselves?
Replacement should be performed by professional technicians, requiring refrigerant recovery, vacuuming, and recharging.

What are the advantages of RS485 output?
It supports multi-point networking, stable data transmission, and is suitable for large systems.

Does sensor accuracy significantly affect air conditioner performance?
Yes. High accuracy enables fine control and contributes to energy savings.

Conclusion

Pressure sensors are a vital foundation for intelligence and energy efficiency in the air conditioning industry. By monitoring refrigerant pressure, they enable system protection, automatic regulation, and efficient operation. Proper selection, installation, and maintenance maximize their advantages. Whether for residential or commercial air conditioning, high-quality pressure sensors are key to improving product competitiveness and user experience. With ongoing technological advancements, future sensors will become even smarter, supporting the sustainable development of the air conditioning industry.