As heat pump systems become more widely used in residential, commercial, and industrial HVAC applications, refrigerant safety has become an important part of system design. A heat pump depends on refrigerant circulation to transfer heat efficiently, but when leakage occurs, the system may face reduced performance, higher maintenance cost, environmental impact, and safety risk.
With the transition to lower-GWP refrigerants such as R32 in R454B, refrigerant leak detection is no longer only a maintenance function. For many modern heat pump designs, the sensor may also support alarm output, fan activation, compressor protection, ventilation control, or other mitigation actions. UL 60335-2-40 guidance explains that refrigerant detection systems in relevant HVAC equipment include both sensors and control logic, and that the system response is tied to refrigerant concentration reaching 25% of the lower flammability limit (LFL).
At Winsen, we provide refrigerant gas sensors and modules for heat pump manufacturers, HVAC OEMs, air-conditioning systems, and refrigeration equipment. Our refrigerant sensor portfolio covers NDIR infrared, thermal conductionin semiconductor technologies, supporting different detection ranges, output methods, installation structures, and refrigerant targets.
Why refrigerant leak detection matters in heat pumps
A heat pump is a closed-loop system, but leakage can still happen at pipe joints, brazed connections, valves, compressors, heat exchangers, or service ports. Even a small leak can gradually reduce cooling or heating capacity and increase compressor workload. In A2L refrigerant systems, leakage also needs to be considered from the perspective of early detection and system response.
For heat pump manufacturers, refrigerant leak detection should solve four practical engineering problems:
- Detect leakage early before refrigerant loss affects system performance.
- Provide stable signal output to the controller or alarm circuit.
- Support safety response logic such as fan operation, alarm, or system shutdown.
- Fit into limited installation space inside indoor units, outdoor units, ducts, or control compartments.
This is why the refrigerant sensor should be selected according to the heat pump architecture, not only by gas name.
Main refrigerants in modern heat pump detection
In current heat pump and HVAC product development, R32 in R454B are two important refrigerants for A2L system design. For these applications, Winsen provides several module options, including ZRT512E-R454B & R32, ZR210, ZRT512C seriesin ZRT510 series. These products are designed for different detection ranges and integration needs, such as 0–100 % LFL, 0–50% LFL, compact thermal-conduction detection, and NDIR-based refrigerant monitoring.
For heat pump projects that also involve other refrigerants, Winsen also provides solutions for R290, R410A, R134A, and broader refrigerant gas detection. Products such as MH-441D, MP511D, MP510Cin ZP201 support different volume-level or ppm-level detection requirements.
How refrigerant leak detection works in a heat pump system
A typical heat pump refrigerant leak detection system includes:
Sensor module
The sensor monitors the surrounding air near a likely leak point or accumulation area.
Signal processing
The sensor converts refrigerant concentration into a digital, analog, UART, RS485, or alarm-related signal depending on the module design.
Controller logic
The heat pump controller evaluates the signal and decides whether to activate fan, alarm, compressor protection, ventilation, or system shutdown.
System response
For A2L systems, the response strategy is often linked to refrigerant concentration thresholds and product safety requirements. UL guidance notes that refrigerant leak detection systems are required to activate system response when refrigerant reaches 25 % LFL, and the requirements also consider sensor reliability, drift, humidity, temperature, pressure, vibration, and self-test behavior over the system life cycle.
This means the sensor is not just a passive component. In many heat pump designs, it becomes part of the equipment safety architecture.
Where should refrigerant sensors be installed in heat pumps?
Sensor placement directly affects detection speed and reliability. A refrigerant detector should be installed where leaked refrigerant is likely to appear or accumulate, such as:
- near the indoor coil area,
- near pipe connections or brazed joints,
- near the lower enclosure area for heavier-than-air refrigerants,
- near the compressor compartment,
- inside duct or airflow channels when required by the system design.
ASHRAE Standard 15 addendum language for machinery rooms also emphasizes that detectors should be located where refrigerant from a leak will concentrate, and that the detector can actuate alarm and mechanical ventilation depending on the application.
For heat pump OEM projects, sensor location should be considered early in the mechanical design stage. Cabinet structure, airflow direction, drainage layout, controller position, and wiring path can all affect the final detection performance.
Winsen solution path for heat pump refrigerant leak detection
Different heat pump products need different sensor structures. At Winsen, we recommend selecting the sensor module according to refrigerant type, detection range, installation space, output interface, and control function.
1. For R32 and R454B heat pumps requiring LFL-based detection
For heat pump systems that need A2L refrigerant detection with controller communication, ZRT512E-R454B & R32 Series is a strong solution. It targets R454B and R32, supports 0–100 % LFL, uses Je n technology, and provides RS485 protocol. The module is designed with high sensitivity, high resolution, and fast response for HVAC, refrigeration, and heat pump applications.
This solution is suitable when the heat pump controller needs stable digital communication and a wider LFL detection range.
2. For compact heat pump structures and low-power designs
For compact heat pump products where installation space is limited, ZR210 provides another practical path. It targets R32 and R454B, uses thermal conduction technology, and is characterized by fast response, small size, low power consumption, long service life, and good anti-condensation performance. Its listed size is 37 × 20 × 7 mm, making it suitable for space-constrained equipment structures.
This type of module is especially useful for compact indoor units, integrated heat pump modules, and designs where condensation resistance is important.
3. For mainstream A2L heat pump detection platforms
For equipment that requires 0–50% LFL refrigerant detection, the ZRT512C series provides a flexible NDIR platform. Winsen offers ZRT512C options for R454B and for R32 / R454B / R290, with high sensitivity, high resolution, and fast response characteristics.
This family is suitable for manufacturers who want a common module platform across multiple A2L refrigerant projects.
4. For refrigerant-specific heat pump designs
Some heat pump manufacturers prefer a dedicated refrigerant-specific solution. In this case, ZRT510 Refrigerant R32 Sensor Module in ZRT510 Refrigerant R454B Sensor Module can be used for more focused product platforms. These NDIR modules are designed for high sensitivity, high resolution, and fast response, with customization flexibility for related refrigerants such as R32, R454B, or R290.
This direction is suitable when the product platform is fixed around one refrigerant and the engineering team wants a more direct validation path.
5. For embedded or ppm-level leak alarm designs
Not every heat pump project requires an LFL-based module. Some applications need a compact ppm-level alarm or auxiliary detection function. For these designs, Winsen provides semiconductor and module-based solutions such as MP511D, MP510Cin ZP201.
MP511D is a semiconductor refrigerant gas sensor with 200–10000 ppm range and characteristics including high selectivity, fast response, and good anti-interference. MP510C is a semiconductor sensor for refrigerant gases including R32, R134a, R410a, and R290, with 100–10000 ppm range. ZP201 is a semiconductor-based refrigerant gas detection module for R32 leakage detection, with a listed alarm value of 5000 ppm.
These products are more suitable for leakage alarm devices, compact monitoring boards, and applications where ppm-level early warning is the main target.
NDIR, thermal conduction, or semiconductor: which one fits heat pumps?
For heat pump manufacturers, the right sensing principle depends on the system function.
NDIR infrared sensors are usually preferred when the system needs stable quantitative detection, LFL-based output, strong selectivity, and integration with the controller. This makes NDIR a strong choice for A2L heat pump platforms using R32 or R454B.
Thermal conduction modules are useful when compact size, low power consumption, fast response, and anti-condensation performance are important.
Semiconductor sensors are suitable for ppm-level leakage alarm, compact alarm devices, and cost-sensitive detection applications.
A practical rule is:
- Izberite Je n for A2L heat pump RDS-oriented detection.
- Izberite thermal conduction for compact R32/R454B module integration.
- Izberite semiconductor for ppm-level leak alarm and early warning devices.
Je n
Polprevodnik
Product selection guide for heat pump manufacturers
| Heat Pump Requirement | Recommended Winsen Direction | Typical Product Options |
|---|---|---|
| R32/R454B, 0–100% LFL detection, RS485 communication | NDIR module for controller integration | ZRT512E-R454B & R32 |
| Compact size, low power, anti-condensation | Thermal conduction module | ZR210 |
| 0–50% LFL A2L detection platform | NDIR refrigerant detection module | ZRT512C series |
| Dedicated R32 or R454B project | Refrigerant-specific NDIR module | ZRT510-R32 / ZRT510-R454B |
| Embedded volume-level refrigerant detection | Compact NDIR module or sensor | MH-Z1542B / MH-441D |
| ppm-level leak alarm | Semiconductor sensor/module | MP511D / MP510C / ZP201 |
Engineering checklist before selecting a heat pump refrigerant sensor
Before choosing a sensor, heat pump manufacturers should confirm:
- Target refrigerant: R32, R454B, R290, R410A, R134A, or mixed refrigerant platform.
- Detection unit: %LFL, %Vol, or ppm.
- Control function: alarm only, fan activation, controller signal, automatic switch-off, or full mitigation response.
- Output method: RS485, UART, analog voltage, PWM, or alarm signal.
- Installation location: indoor coil area, lower enclosure, duct, compressor section, or custom PCB area.
- Environmental condition: humidity, condensation, vibration, dust, oil mist, and temperature range.
- Service life requirement: long-term drift, calibration strategy, and maintenance access.
This selection process helps avoid common problems such as delayed detection, false alarms, poor installation fit, unstable output, or mismatched controller integration.
pogosta vprašanja
Why do heat pumps need refrigerant leak detection?
Refrigerant leak detection helps identify leakage early, reduce system performance loss, support alarm or shutdown logic, and improve safety in heat pump systems using modern refrigerants.
Which refrigerants are most important for heat pump leak detection?
For modern A2L heat pump systems, R32 in R454B are key refrigerants. Winsen provides several modules targeting these gases, including ZRT512E, ZR210, ZRT512C, and ZRT510 series.
Which Winsen sensor is suitable for R32 and R454B heat pumps?
For R32 and R454B heat pump platforms, ZRT512E-R454B & R32 is suitable for 0–100% LFL detection and RS485 integration, while ZR210 is suitable for compact low-power designs.
Can semiconductor sensors be used in heat pump leak detection?
Yes. Semiconductor sensors such as MP511D, MP510Cin ZP201 can be used for ppm-level refrigerant leakage alarm and compact detection applications.
Where should the sensor be placed in a heat pump?
The sensor should be placed near likely leakage or accumulation areas, such as the indoor coil area, lower enclosure, pipe joints, compressor compartment, or airflow path. ASHRAE guidance for machinery rooms also emphasizes locating detectors where leaked refrigerant will concentrate.
Zaključek
Refrigerant leak detection for heat pumps is not a simple “add a gas sensor” task. It requires matching the sensor principle, detection range, output method, installation structure, and response logic to the actual equipment design.
For R32 and R454B heat pump projects, Winsen provides multiple solution paths: NDIR moduli for LFL-based A2L detection, thermal conduction modules for compact low-power integration, and semiconductor sensors for ppm-level leak alarm. By selecting the right solution at the design stage, heat pump manufacturers can build safer, more reliable, and easier-to-integrate refrigerant detection systems.
