Lennox 78H55 Transformer

The Lennox 78H55 Transformer is a critical OEM replacement part designed for HVAC 24V control circuits. This step-down transformer converts a 120V primary input to a stable 24V secondary output, providing the necessary low-voltage power for contactor coils, ignition modules, and thermostats. With a 30VA power rating, it is engineered for consistent performance in residential and light commercial air handlers and furnaces. This unit serves as the direct replacement for Lennox 78H5501, ensuring a match for footprint and electrical specifications without the need for field modifications. Featuring a foot-mount design and QuickConnect terminals, it simplifies the swap-out process for technicians in the field. Maintaining the correct volt-ampere capacity is essential for preventing voltage drops that can lead to intermittent system lockouts or component chatter. For contractors servicing Lennox equipment, this genuine Lennox part ensures compatibility with the original manufacturer's wiring harness and circuit protection standards.

• Direct OEM Compatibility: Specifically designed to replace the Lennox 78H5501, ensuring perfect physical and electrical alignment.
• Simplified Installation: Features QuickConnect terminals and a standard foot-mount base to reduce labor time during service calls.
• Reliable Power Delivery: Provides a steady 30VA rating at 60Hz, optimized for powering furnace control boards and 24VAC accessories.
• Heavy-Duty Construction: Built to withstand the high-temperature environments typical of HVAC burner compartments and blower housings.

• Is the Lennox 78H55 a direct replacement for the 78H5501? Yes, the 78H55 is the updated manufacturer part number that replaces the older 78H5501 while maintaining the same 120V to 24V conversion ratio and mounting specs.
• Can this transformer be used with 208V or 240V systems? No, this is a dedicated 120V primary transformer. Applying higher line voltage will damage the internal windings and the connected low-voltage components.
• What happens if my system exceeds the 30VA limit? Drawing more than 30 volt-amperes can cause the transformer to overheat and eventually fail. Always calculate the total amp draw of your contactors, relays, and accessories to ensure they do not exceed the 1.25-amp secondary limit.

Disclaimer: While we strive for 100% accuracy, product data and specifications are subject to change. Please contact our team to confirm compatibility or technical details before purchasing.