Programmable Thermostat

This Class 2 replacement transformer is engineered to deliver reliable power for 24V control systems in HVAC, heating, and automation applications. With a 40 VA power rating and 120 VAC primary voltage converting to 26.5 VDC secondary voltage, it efficiently powers thermostats, gas valves, relays, and other low-voltage control devices at 50/60 Hz operation. The unit measures 2 7/32 inches wide by 2 inches deep by 3 7/32 inches high and features a NEMA Type D plate-mount enclosure designed for secure junction box installation on a standard 4x4 inch mounting plate. Connections include nine-inch color-coded lead wires on the primary side for straightforward installation and two screw terminals on the secondary for reliable component connections. Rated for ambient temperatures from negative 20 to 105 degrees Fahrenheit, this transformer maintains consistent performance across diverse indoor and outdoor installations. The unit meets NEMA DC20-1992 energy limiting standards and complies with NEC Class 2 requirements for dry applications and Class 3 for wet locations, ensuring safety and code compliance in residential, commercial, and industrial settings. Built as a direct replacement for the Resideo AT72D1006/U (Honeywell Home), it provides dependable operation for HVAC system control, making it an essential component for technicians and contractors maintaining or upgrading heating and cooling systems.