Description
The Cleveland Controls AFS-228 Air Flow Sensing Switch is a reliable, proven solution for detecting the presence or absence of airflow in HVAC air handling systems. Designed for use in commercial and residential applications, this sensing switch helps protect equipment by confirming proper airflow before allowing downstream components — such as heating elements, cooling coils, or UV systems — to energize.
How It Works
The AFS-228 uses a differential pressure sensing mechanism to detect airflow across a duct or air handling unit. When airflow meets the switch’s set point, the internal contacts change state, signaling the control system that safe operating conditions exist. If airflow drops below the threshold — due to a failed blower, clogged filter, or closed damper — the switch opens, providing a critical safety interlock.
Key Features
- Differential pressure-based airflow detection for accurate, repeatable performance
- Compact, durable housing suitable for duct or air handler installation
- Snap-action switching mechanism for positive, reliable contact operation
- Adjustable sensitivity to accommodate a wide range of duct velocities and system configurations
- Suitable for use as a safety interlock in commercial HVAC air handling systems
- Easy field installation with standard duct penetration fittings
Typical Applications
- Air handling units (AHUs) and fan coil units
- Duct-mounted airflow verification and safety interlocking
- Electric heating element protection
- UV light system enable/disable control
- Blower and fan proving circuits
- Building automation and DDC system integration
Why Choose Cleveland Controls
Cleveland Controls has been a trusted name in HVAC sensing and switching technology for decades. The AFS series air flow switches are engineered for long service life and consistent performance in demanding commercial environments, making the AFS-228 a go-to choice for HVAC contractors and building engineers alike.







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