Johnson Controls S351AA-1 Module

The Johnson Controls S351AA-1 is a professional-grade humidity stage module designed to integrate seamlessly with the System 350? ecosystem, specifically the W351 humidity control series. This module allows technicians to expand the capabilities of a base controller by adding an additional stage of equipment control, utilizing a high-reliability SPDT enclosed relay. Built for demanding commercial and industrial HVACR environments, the S351AA-1 provides a tactile percent RH scale for precise field adjustments, ensuring your humidification or dehumidification sequences trigger exactly when required.

Engineering-grade flexibility is a core feature, as this module supports both wall-mount and DIN rail mount configurations. The unit offers a 2 to 10% RH differential adjustment and a 2 to 30% RH offset range, allowing for tight control over short-cycling and precise staging intervals. Whether you are managing complex cleanroom environments or standard building automation, the multi-stage humidity control provided by the S351AA-1 module ensures the mechanical systems respond accurately to fluctuating latent loads without unnecessary component wear.

• System 350 Compatibility: Engineered specifically to plug into Johnson Controls W351 controllers for rapid multi-stage expansion.
• Precise Delta Management: Features an adjustable 2 to 10% RH differential to prevent frequent equipment cycling.
• Versatile Relay Output: Equipped with an SPDT output relay rated for 1/2 hp at 120/240 VAC, suitable for various pilot duty and inductive loads.
• Simplified Installation: Supports standard 35mm DIN rail mounting or direct surface mounting for quick field retrofits.
• Visual Status: Includes a built-in LED indicator to provide immediate confirmation of relay energization during troubleshooting.

Common Questions & Answers

Can the S351AA-1 be used for both humidification and dehumidification?
Yes. The mode is determined by the internal jumper settings (J2). Positioning the jumpers vertically configures the module for humidification (Reverse Acting), while a horizontal position sets it for dehumidification (Direct Acting).

Does this module require a separate power supply?
When plugged directly into a System 350 control module, the S351AA-1 receives its 24V power and sensor signal through the internal 5-pin connector. No additional external power source is needed for the logic circuit.

What is the maximum number of S351 modules I can add to a W351 control?
The W351 series typically supports adding multiple stage modules; however, the total is limited by the power consumption of the base controller's transformer. Always calculate the total VA (1.0 VA per S351AA-1) to ensure the system remains within capacity.

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.