Johnson Controls P29NC-2 Pressure Control

For veteran technicians managing chiller protection or oil pressure safety, the Johnson Controls P29NC-2 is the industry standard for reliable low-pressure cutout. This manual reset control is designed to protect compressors from damage due to sustained loss of suction pressure or lubrication failures. It supports both 120/240 Vac applications and features a robust 60-second thermal time delay relay, which prevents nuisance tripping during initial start-up or transient pressure fluctuations. With an adjustable range of 20" Hg to 100 PSIG, this unit offers the precision required for complex HVACR refrigeration cycles. The P29NC-2 serves as the direct P29NC-34 replacement and P29NC-2C replacement, ensuring a seamless fit for legacy system maintenance. Its SPST snap-acting switch provides a clean break in the control circuit, while the trip-free manual reset requires physical intervention to confirm the system is safe for operation after a cutout event.

Key Benefits:

• Precision Pressure Monitoring: Wide adjustable range from 20 inches Hg vacuum up to 100 PSIG for versatile system integration.
• Enhanced Compressor Protection: 60-second time delay allows the system to stabilize, preventing unnecessary shutdowns while protecting against prolonged low-pressure states.
• Universal Compatibility: The Johnson Controls P29NC-2 is a drop-in replacement for P29NC-34 and P29NC-2C models, significantly reducing downtime during service calls.
• Rugged Construction: Built with high-profile pressure elements to withstand high over-pressures and industrial environments.
• Field-Serviceable Timing: The time delay relay assembly is replaceable, allowing for easy onsite repairs without replacing the entire low pressure cutout control.

Common Questions:

How do I wire the P29NC-2 for 240V systems?
The internal terminal board is designed for 120/240 Vac pilot duty. Ensure the heater circuit matches your supply voltage; for 208V applications, it is often recommended to use a neutral wire to power the 120V heater circuit for optimal timing accuracy.

Can I use this for ammonia refrigeration?
Standard P29 models are designed for non-corrosive refrigerants. If you are working with ammonia, verify the material compatibility of the 1/4" flare connection and pressure element before installation.

What causes a manual reset lockout?
A lockout occurs when the pressure remains below the setpoint for longer than the 60-second delay. This indicates a potential leak, refrigerant loss, or oil pressure lubrication failure that must be cleared by a technician before the manual reset will hold.

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.