Lennox 78H55 Furnace Transformer

Lennox 78H55 Furnace Transformer delivers reliable 24V control power for Lennox furnaces, converting 120 V AC primary to 24 V AC secondary. This 60 Hz, 30 VA furnace transformer is designed as a replacement part for compatible Lennox furnace control circuits and relays. Its compact dimensions—2.25 in W x 2.57 in D x 1.94 in H—ease installation in tight furnace compartments and service spaces.

Built to endure typical furnace environments, this transformer ensures steady operation of thermostats, relays, and control boards by delivering a stable 24V control voltage. It’s intended for use on furnaces that require the Lennox 78H55 configuration, providing a dependable power bridge between the 120V mains and the 24V control circuit.

• Model: Lennox 78H55
• Primary voltage: 120 V AC
• Secondary voltage: 24 V AC
• Frequency: 60 Hz
• Power rating: 30 VA
• Dimensions (W x D x H): 2.25 in x 2.57 in x 1.94 in
• Application: Replacement furnace transformer for Lennox systems