01Airflow Monitoring at Blower Outlets and Main Supply Ducts

The actual airflow delivered by a blower changes with system resistance and operating conditions. When resistance increases in ducts, filters, or downstream equipment, delivered airflow may decrease. A measurement point can therefore be established at a suitable duct location connected to the blower to track airflow under different operating conditions.

The AFMC HVAC Average Flow Measuring Tube uses the Pitot-tube principle and a multi-hole averaging structure to collect pressure information at different points across the duct, reducing the limitations of relying on a single measurement location. Paired with the PMM330 Differential Pressure Transmitter, it provides differential pressure data that can be used to calculate air velocity and airflow based on the tube coefficient, air conditions, and duct cross-sectional area. This configuration suits general airflow monitoring where cost efficiency and ease of maintenance are priorities.

Install the measuring tube in a suitable duct section according to site airflow conditions and the product installation requirements. Avoid locations too close to elbows, dampers, or blower outlets where airflow disturbances are greater, so that the readings better represent conditions in the duct section.

02HVAC Airflow Display and Monitoring Integration

HVAC systems typically include outdoor air, supply air, and return air ducts. Airflow in these ducts changes as occupancy requirements shift or the air conditioning system switches operating modes. Continuous monitoring in main ducts and critical branches allows airflow distribution among areas to be compared and helps operators understand air distribution performance.

The AFMC combined with the FDM06-X Thermal Mass Diff. Pressure Signal Processor integrates multi-point pressure averaging with differential pressure signal processing. Once the tube coefficient, duct cross-sectional area, and measurement conditions are configured, air velocity and airflow information can be obtained. The FDM06-X has a built-in display for on-site checks and can connect to control or monitoring systems through the selected outputs and communications configuration.

This configuration suits HVAC airflow monitoring that requires both on-site readings and centralized management. Comparing airflow trends with fan speed, damper opening, and equipment operating schedules provides a useful reference for supply air adjustments and troubleshooting.

03Integrated Measurement for AHUs and Medium to Large Ducts

When adding measurement points to AHUs or medium to large ducts, the available measurement range is not the only consideration. Space around equipment, tubing arrangement, and maintenance access are also important. An integrated measurement option may be suitable when external pressure tubing and separate instruments need to be minimized.

The FDM06-P Average Flow Thermal Mass Transmitter integrates the Pitot tube and transmitter into one assembly. It uses Pitot-tube pressure tapping and differential pressure measurement to obtain airflow information and provides a local display. Compared with a separate-component arrangement, it reduces external tubing and accessories and simplifies installation at the equipment.

Depending on the required measuring range and installation conditions, this option can be applied to AHUs, blowers, and medium to large ducts to monitor equipment discharge and duct airflow for operation checks and routine inspections.

04Air Velocity Measurement in VAV Boxes and Low-Flow Duct Sections

VAV boxes adjust supply airflow according to zone requirements, so air velocity in the duct varies as dampers operate. If the system spends extended periods at low airflow, the minimum operating air velocity should be considered during product selection to ensure the measuring range covers real conditions.

The FTS34 / 35 Air Velocity Transmitters measure air velocity directly through airflow-induced heat transfer. Depending on probe type and installation requirements, they can be installed in HVAC ducts, VAV boxes, or laboratory / test ducts. Where volumetric airflow is needed, the duct cross-sectional area must be considered and the measurement point must be representative of the flow profile.

In low air velocity ducts, probe placement, mounting orientation, and flow distribution can all affect measurement results. Plan the measurement point according to the product installation requirements and verify its performance under actual operating conditions.

05Choosing an Averaging Flow Measuring Tube for Site Conditions

In addition to duct dimensions, an averaging flow measuring tube should be selected with consideration for gas properties, temperature, humidity, and material compatibility.

The AFMC HVAC Average Flow Measuring Tube is suitable for general blower, HVAC, and VAV Box air measurement applications. Where tube material, pressure rating, or industrial environmental resistance are more demanding, the AFMP Average Flow Measuring Tube can also be evaluated. Select the material and specification according to actual operating conditions.

Both products use multi-point pressure averaging. The final configuration must also consider the measuring range of the differential pressure transmitter or signal processor, the tube coefficient, and installation conditions to establish a complete air velocity and airflow measurement solution.

06Continuous Airflow Monitoring from Equipment Outlets to Terminal Branches

Blower and HVAC airflow monitoring points can be installed at equipment discharge ducts, main supply and return ducts, or terminal branches according to management needs. Comparing measurements across locations and operating periods helps track airflow distribution and changes, narrowing the scope of equipment inspection and duct troubleshooting.

eyc-tech offers configurations including PMM330 + AFMC, FDM06-X + AFMC, FDM06-P, and FTS34 / 35 for general airflow monitoring, local display and system integration, integrated installation, and low air velocity measurement. By choosing suitable measurement points and bringing the data into existing controls and monitoring workflows, operators can obtain continuous, traceable information for operation verification, troubleshooting, and maintenance planning.

07Support Energy-Efficient Environmental Control and Sustainable Smart Buildings with Continuous Measurement

For smart buildings, airflow data can be integrated with building management systems based on the selected product outputs and communications options. Alongside temperature, humidity, occupancy requirements, and electricity consumption records, this helps operators assess whether air supply matches actual demand. The information can guide fan operation, damper position, and scheduling adjustments while maintaining required ventilation and indoor environmental quality.

From measurement and data integration to improvement tracking, eyc-tech air velocity and airflow solutions provide a data foundation for energy-efficient environmental control. Comparing operating performance before and after improvements alongside actual electricity use can help evaluate the effectiveness of energy-saving measures and support verifiable sustainability improvements in smart buildings.