The ZoneFirst SPRD-10 is a heavy-duty 10-inch round barometric static pressure regulating damper engineered for bypass air management in multizone HVAC systems. Constructed from 22-gauge zinc-plated galvanized steel, this mechanical bypass damper requires no electrical wiring, utilizing a single-blade counterbalanced gravity design to automatically relieve excess duct static pressure. As individual zone dampers close, the SPRD-10 responds to the rising upstream pressure, opening the blade to bypass air to a return plenum or dump zone. This self-regulating action is critical for maintaining consistent airflow (CFM) across the evaporator coil, preventing equipment short-cycling, coil icing, and excessive air noise at the registers. The adjustable weighted arm allows technicians to fine-tune the opening threshold—typically up to 0.5" W.C.—ensuring the HVAC bypass system operates at peak efficiency regardless of zone demand. Key Benefits for Technicians Automatic Pressure Relief: Responds instantly to changes in static pressure without the need for electronic sensors or actuators. Variable Weighted Arm: Features an adjustable counterweight for precise field calibration to match specific blower motor curves and duct configurations. Equipment Protection: Helps prevent high-limit trips or frozen coils by ensuring minimum required airflow through the air handler. Durable Construction: Built with a 22-gauge steel 10-inch sleeve and a corrugated blade for long-term rigidiity in high-velocity residential and light commercial applications. Versatile Mounting: Optimized for horizontal runs but adaptable for vertical airflow when the counter-balance is properly offset. Common Questions & Technical Support How do you size the SPRD-10 for a bypass run? Calculate the total system volume (CFM) and subtract the CFM of your smallest zone. The difference is the amount of air the bypass damper must handle. The SPRD-10 is rated for systems requiring roughly 750-800 CFM of bypass air. Where is the ideal installation location? Install the barometric damper in a bypass duct between the supply plenum (before any zone dampers) and the return air duct. For best results, place it as far from the air handler as possible to minimize turbulence. Can this be used with variable speed blowers? While compatible, always verify the static pressure settings. In many variable speed applications, a barometric damper like the ZoneFirst SPRD-10 provides a reliable, cost-effective mechanical fallback to ensure airflow stability. 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.
