Cleveland Controls DFS-221-156 Switch

The Cleveland Controls DFS-221-156 is a heavy-duty, fixed-point air pressure sensing switch engineered for precision airflow verification in HVAC, duct heater, and combustion systems. As a direct FS-BO-179 cross reference, this SPDT switch is factory-calibrated to actuate on a pressure rise of 0.05" w.c. (+/- 0.02"), making it a critical safety component for proving draft in boilers and furnaces. Its open-mounted design is specifically optimized for surface-mounting in tight mechanical spaces where internal access is restricted.

Utilizing a durable silicone diaphragm and a snap-acting switch rated for 15 amps, the Cleveland Controls air flow switch is capable of sensing positive, negative, or differential pressure. The unit features dual 1/4" OD slip-on sample line connectors and 1/4" quick-connect electrical terminals to ensure a fast, secure fit during field replacement. Designed for longevity, it is rated for 100,000 cycles at maximum electrical load and can handle up to 0.5 PSI of maximum pressure.

Key Benefits

• Precise Airflow Proving: Fixed 0.05" w.c. set point ensures consistent differential air pressure detection for system safety.
• High Compatibility: Direct OEM replacement for Cleveland Controls DFS-221-156 and 243C67, simplifying inventory for service contractors.
• Versatile Sensing: Configurable for positive, negative, or differential pressure applications in duct heaters and industrial ovens.
• Rugged Construction: Zinc-plated steel housing and silicone diaphragm provide reliable performance in temperatures ranging from -40°F to 180°F.
• Contractor Grade: Tool-free barbed sample line connections facilitate rapid troubleshooting and installation.

Common Questions

Does this switch require field calibration?
No, the DFS-221-156 features a factory-fixed set point of 0.05" w.c. and is non-adjustable to prevent tampering and ensure safety standards.

In what position should this switch be mounted?
To maintain the specified 0.05" w.c. set point, the switch must be mounted with the diaphragm in a vertical plane. Avoid mounting with sample line connections facing upward to prevent moisture accumulation.

Is this compatible with combustion byproducts?
Yes, the internal silicone diaphragm is designed to withstand air or combustion byproducts that do not degrade silicone materials.

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.