Pressure sensors for HVAC applications measure at very low ranges — from a few Pascal for room pressure control to a few hundred mbar for duct pressure and filter monitoring. Accuracy, long-term stability, output signal and mounting type must match the specific application. This guide covers the key selection criteria and leads into the sensor selector.
HVAC applications use pressure measurement for air flow control, filter monitoring, room pressure regulation, duct pressure and fan control. These are typically low-pressure differential measurements — often in the range of a few Pascal to a few hundred mbar. The sensors must be compact, stable over time and suitable for air or clean gas media.
Differential pressure across air filters indicates filter loading. Sensors must detect small pressure changes reliably over long periods. Typical range 0–500 Pa or 0–100 mbar. Output may be a switching output or analogue signal.
Cleanrooms, isolation rooms and operating theatres require controlled positive or negative pressure relative to adjacent spaces. Very low ranges (0–50 Pa or 0–25 Pa) and high stability are required.
Duct static pressure measurement for fan and air handling unit control. Typical range 0–1000 Pa to 0–5000 Pa. Static pressure probes, pitot tubes or duct pressure fittings are commonly used. Output to BMS via 4–20 mA, 0–10 V or digital interface depending on the device.
AHUs use duct static pressure and differential pressure for fan control, filter monitoring and airflow supervision. Typical outputs include 0–10 V, 4–20 mA, switching outputs and building automation interfaces.
Low-pressure differential sensors for HVAC operate in a different range from industrial process transmitters. Key specifications differ significantly:
| Specification | HVAC / low-pressure DP | Industrial process DP |
|---|---|---|
| Typical range | Few Pa to several kPa; some HVAC applications extend into tens or hundreds of mbar | mbar to bar ranges depending on process application |
| Media | Air, clean gas, non-condensing | Liquids, gases, steam |
| Accuracy | Often specified as %FS or Pa; stability and zero drift are critical for low-pressure applications | Often specified as %FS or %span with higher process accuracy requirements |
| Output | 0–10 V, 4–20 mA, switching | 4–20 mA, HART, fieldbus |
| Mounting | Panel, duct, wall mount | Inline, manifold, flanged |
| Communication | BACnet, Modbus or LON on selected devices | HART, PROFIBUS, Foundation Fieldbus depending on device type |
| Criterion | What to check |
|---|---|
| Pressure range | Select the smallest range that covers the application. Oversized range reduces resolution and accuracy for HVAC applications. Bidirectional ranges (e.g. ±500 Pa) may be needed for room pressure control. |
| Reference type | Differential (two process connections) for filter DP and room pressure. Gauge for duct static pressure (one process connection, atmospheric reference). Verify which type is needed. |
| Output signal | 0–10 V is common for HVAC systems. 4–20 mA for longer cable runs or noisy environments. Switching outputs for simple filter alarms. Modbus or BACnet may be available on selected devices for building management system integration. |
| Mounting | Duct mounting with static pressure probe or pitot tube for duct pressure. Panel or wall mounting for room pressure sensors. Verify mounting orientation — many low-pressure sensors are position-sensitive. |
| Temperature range | Indoor HVAC: 0–50 °C ambient typically sufficient. External air intakes or plant rooms may require wider range. Verify the compensated temperature range for accurate measurement across the full ambient range. |
| Long-term stability | HVAC sensors often operate for years without recalibration. Verify the long-term stability specification — particularly for very low-pressure applications where drift can be significant relative to the range. |
A sensor rated to 0–100 mbar used for a 0–10 mbar application loses most of its resolution and accuracy. Select a range appropriate to the measurement task — ideally with the maximum expected pressure at 70–90% of full scale.
Many low-pressure differential sensors are position-sensitive — the output can change if the sensor is mounted in a different orientation from the calibration position. Verify the orientation requirement and mount accordingly. Some devices provide orientation compensation or field zeroing, but this must be confirmed in the datasheet.
Room pressure control requires true differential measurement between two spaces — not gauge pressure relative to atmosphere. Verify the sensor type (differential, gauge or absolute) matches the measurement requirement.
Verify before specifying: Always confirm pressure range, reference type, output signal, mounting orientation and long-term stability against the manufacturer specifications. Pressure Selector provides a shortlist for further evaluation — it does not replace engineering review or certification assessment.
For promising matches, use Request Info on any result to prepare a supplier inquiry based on your application requirements.
Pressure Selector converts application requirements — such as pressure range, differential or gauge type, output signal, mounting type and media — into a structured shortlist of matching pressure sensors for HVAC and building applications.
Coverage includes selected low-pressure and differential pressure sensors from manufacturers such as Honeywell, All Sensors, SSI Technologies, Setra, Ashcroft and others. Availability of specific output types, communication protocols and mounting options depends on the selected series and configuration.