Cleveland Controls AFS-953-B Sensing Switch

The Cleveland Controls AFS-953-B is a contractor-grade differential pressure sensing switch engineered for high-accuracy monitoring of air and non-combustible gases in commercial HVAC draft control systems. This SPDT air pressure switch features a versatile field-adjustable set point range from 0.05" w.c. to 12.0" w.c., providing precise airflow proving for combustion air, furnace pressure, and blower operation. A critical feature for technicians is the integrated 20-second pre-purge delay coupled with an 8-second time delay relay sequence, which effectively eliminates nuisance shutdowns caused by momentary draft fluctuations or air turbulence. Designed for 115Vac operation, the AFS-953-B utilizes rugged screw-type terminals and 1/4" NPT female connectors for secure sampling line integration. Whether you are managing low negative pressure cutoff or monitoring filter loading, this switch delivers the mechanical reliability required for automated building management systems and industrial ventilation logic.

Key Benefits

• Dual Delay Logic: Features a factory-set 20-second pre-purge and 8-second delay to ensure stable operation during startup and transient airflow conditions.
• Broad Operating Range: Field-adjustable from .05" to 12" w.c., making it a universal solution for various static and differential pressure applications.
• Industrial Build: Housed in a durable enclosure with SPDT contacts rated for pilot duty, ensuring compatibility with standard 115V control circuits.
• Flexible Installation: Dual 1/4" NPT sampling ports allow for positive, negative, or differential pressure sensing in any vertical orientation.

Common Questions

How do the time delays affect the burner sequence?
The 20-second pre-purge delay ensures sufficient airflow is established before the ignition sequence begins, while the 8-second delay prevents the system from tripping due to minor pressure "hiccups" or wind gusts at the venting stack.

Does this switch support manual reset?
No, the AFS-953-B is an automatic reset model. Once the pressure returns to the specified differential, the SPDT contacts will revert to their normal state without manual intervention.

Can this be mounted horizontally?
For maximum accuracy at the lowest set points, the diaphragm must be mounted in a vertical plane. Horizontal mounting can shift the calibration due to the weight of the internal diaphragm.

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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.