Exceeding this limit may damage the silicone diaphragm or internal calibration spring

Technicians often encounter fault codes related to "Flue Damper Switch Open" or find the burner failing to ignite because the end switch in the damper was not reached

but always verify the specific orifice size against the manufacturer's charging chart for the tonnage of the outdoor unit

Reliable Signal Processing: High-quality capacitors and resistors provide stable 24V and DC signal paths for sensitive communication between indoor and outdoor sections

Optimized Pressure Regulation: Engineered to provide the specific CFM airflow required to keep the system's pressure switch engaged during the entire heating cycle

Resideo AT120A1004 Transformer 328140-751 Exceeding this limit may damageThe Resideo AT120A1004 is a versatile, high reliability 20VA foot mount transformer engineered for integration into 24V control circuits. This multi tap power source supports 120V, 208V, and 240V primary input configurations, providing a stable 27V secondary output at 60Hz. Designed for the rigors of field service, the AT120A1004 offers multiple mounting options, including foot mounting or plate mounting on standard 2x4 or 4x4 outlet boxes. With