If flame rectification is not sensed within the 10-second TFI

Universal Mounting: Supports 35mm DIN rail or screw-on mounting with a flexible +/-180 degree vertical rotation tolerance

reducing electrical strain on the system during cyclical operation

OEM Compatibility: Exact-fit replacement for Laars boilers

making it ideal for vacuum and low-pressure gravity-fed systems

Resideo ZD8X20TZ Damper 320788-704 If flame rectification is notThe Resideo ZD8X20TZ is a heavy duty, rectangular zone damper specifically engineered for professional HVAC zoning applications. Measuring 8 inches wide by 20 inches high, this parallel blade damper is constructed with an extruded aluminum frame and blades to ensure long term structural integrity in high velocity systems. It features a high torque 24VAC synchronous motor mounted on the 20 inch side, providing a power closed spring return open