Cleveland Controls DFS-221-347 Air Flow Switch

The Cleveland Controls DFS-221-347 Air Flow Switch is a high-performance, non-adjustable differential pressure switch designed for precise air flow proving in duct heaters, ovens, and technical HVAC applications. This SPDT air flow switch is fixed to operate on a pressure rise at .05" ± .02" w.c., ensuring consistent system monitoring without the risk of field-adjustment errors. Capable of sensing positive, negative, or differential pressure, it features a rugged plated housing with a silicone-based diaphragm compatible with air and non-corrosive combustion by-products. Supporting a broad voltage range of 120-277Vac, this unit integrates seamlessly into diverse control circuits. The DFS-221-347 is the direct engineering replacement for the discontinued DFS-221-271, offering the same 1/4" barbed connections and compact footprint for surface-mounting in restricted spaces. With a maximum pressure rating of 1/2 PSI and an operating range down to -40°F, this switch is a reliable standard for veteran contractors and facility managers requiring HVAC pressure switch precision.

• Direct Replacement: Engineered as the exact substitute for DFS-221-271, eliminating mounting or compatibility issues during retrofits.
• Flexible Sensing: Dual slip-on sample line connectors allow for differential pressure sensing across filters or coils, as well as standalone positive or negative pressure monitoring.
• High Electrical Compatibility: Rated for 120-277Vac with a 15A non-inductive load capacity, making it suitable for both pilot duty and direct control.
• Durability: Built for 100,000 cycles at maximum rated load, featuring a silicone diaphragm resistant to common combustion by-products.
• Easy Installation: Features standard 1/4" barbed connections for flexible 3/16" or 1/4" ID tubing and a versatile mounting strap bracket.

Can the DFS-221-347 be used for negative pressure sensing?
Yes. By connecting the sample line to the low-pressure (L) inlet and leaving the high-pressure (H) inlet open to the atmosphere, the switch will accurately detect negative pressure (vacuum) rise.

What is the correct mounting orientation for this switch?
To maintain the specified fixed set point of 0.05" w.c., the unit must be mounted with the diaphragm in a vertical plane. Avoid mounting with the barbed connections facing upward to prevent moisture or debris accumulation.

Is this switch suitable for high-temperature exhaust monitoring?
The unit is rated for ambient temperatures up to 180°F and is compatible with combustion by-products, provided they do not contain chemicals that degrade silicone.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.