Johnson Controls P47AA-4 Pressure Control

The Johnson Controls P47AA-4 Pressure Control is a heavy-duty steam pressure limit control engineered for high-limit cutout or operating control in commercial and industrial steam heating systems. This SPST pressure switch is designed to provide professional-grade reliability, featuring contacts that open on pressure rise to safeguard against overpressure conditions. With a versatile electrical rating of 120/208/240/277 Vac, the P47AA-4 integrates seamlessly into various power configurations for HVAC high limit applications.

This model features a broad operating pressure range of 20" Wc to 50 Psig and an adjustable differential pressure of 5 to 35 Psi, allowing for precise system tuning. Built for durability, it supports a maximum allowable pressure of 180 Psi. The automatic reset functionality ensures the system resumes operation once pressure returns to safe levels, minimizing downtime for technicians. Explicitly serving as the direct replacement for P47AA-6, this unit offers a 1/4 inch internal NPT connection and an easy-to-read "sight-set" scale for rapid field adjustments.

• Enhanced Compatibility: Serves as the primary P47AA-6 replacement for legacy steam boiler controllers.
• Robust Construction: Long-life contact structure with high contact force designed for steam boiler safety.
• Versatile Media: Suitable for use with steam, water, air, and non-combustible gases that are non-corrosive to copper and brass.
• Precision Control: Features a dual-scale sight glass for simultaneous viewing of cut-in and cut-out settings.
• Trip-Free Reset: Reliable automatic reset mechanism ensures consistent cycling without manual intervention.

Common Questions

What is the difference between P47AA and P47BA?
The P47AA-4 is an "open on rise" control typically used for high-limit cutout, while the P47BA series "closes on rise" and is often used to energize equipment like unit heater blowers when steam pressure is achieved.

Can this be mounted directly to a boiler?
Yes, it should be mounted to a boiler tap above the water level. Use of a steam siphon (pigtail) is required to prevent live steam from entering the bellows, which protects the internal components from extreme thermal stress.

Is this compatible with 24V control circuits?
While it has a line voltage rating up to 277 Vac, the P47AA-4 features silver-plated contacts that are also suitable for low-voltage (24V) pilot duty applications.

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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.