Description
The Lennox 78W05 Transformer is an electrical step-down component with a 400V primary winding and a 24V secondary output, used to supply low-voltage power to control circuits in HVAC systems. It converts higher incoming line voltage into a reduced, stable voltage suitable for relays, thermostats, and control boards. The transformer is commonly installed in commercial and residential heating and cooling equipment where consistent control voltage is required. It serves as a power supply interface within the system, enabling safe operation of control components and supporting proper system operator across heating and air conditioning applications.









