ZoneFirst MSS Damper Actuator

The ZoneFirst MSS Damper Actuator is a 24VAC spring return damper motor engineered for direct replacement of legacy MSR damper motor, MCS-3, MCSR, RDM, and RDMH models. Specifically designed for professional-grade HVAC zoning systems, this 2-wire actuator provides silent operation with a patented air brake system that prevents the slamming and gear noise common in standard spring-return units. The direct drive actuator powers the damper to the closed position and utilizes a fail-safe mechanical spring to pull the blade open during power loss, or it can be field reversible to meet specific project configurations. Built for longevity, this 2-wire HVAC actuator features a synchronous hysteresis motor and a "lost motion" drive train to protect internal gears from closing shock. It integrates seamlessly with ZoneFirst ZDS, ZDB, RDS, and RTS dampers, offering a 60 inch-ounce torque rating to ensure reliable blade positioning in high-static environments.

• Universal Compatibility: Serves as the primary replacement for ZoneFirst MSR and Trol-A-Temp models, reducing the need to stock multiple SKUs.
• Silent Operation: Features a patented air brake that slows the return motion, eliminating the loud "clunk" often heard in residential ductwork.
• Field Serviceable: The quick-release hex wrench mounting and slip-on wiring cover allow for rapid swaps in the field.
• Fail-Safe Design: Mechanical spring return open damper functionality ensures airflow is maintained if 24V power is interrupted.
• Enhanced Durability: Rated for over 250,000 cycles with a wide operating temperature range from 0°F to 150°F.

Is the ZoneFirst MSS a direct replacement for the MSR?
Yes, the ZoneFirst MSS is the designated replacement for older MSR, RDM, and RDMA motors. It fits the same 5/16-inch damper shafts and uses the same 2-wire 24VAC configuration.

Can I change the motor to power-open instead of power-closed?
This is a field-reversible damper actuator. By adjusting the internal configuration, a technician can flip the orientation to function as power-to-open and spring-to-close depending on the zone's requirements.

How do I confirm the damper blade position?
The motor housing includes a minimum position adjustment screw that aligns with the internal damper blades. When the setscrew is aligned with the duct, the damper is open; when hidden behind the motor, it is in the closed position.

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.