Lennox 47K20 Transformer

The Lennox 47K20 Transformer is a heavy-duty step-down control transformer engineered for high-demand HVAC low-voltage control circuits. Designed to provide a reliable 24V secondary output from a 208/240V primary input, this 40VA Class 2 transformer ensures consistent power delivery to contactors, relays, and integrated furnace control boards. This unit is a direct OEM replacement part and is technically identical to the Lennox 47K2001 and the R39370B001 model. Built with a robust foot mount configuration and quick-connect spade terminals, it allows for fast, secure field integration. Whether you are servicing a residential air handler or a light commercial rooftop unit, the 47K20 provides the electrical stability required to prevent voltage drops or control failures in 60Hz systems. This Lennox 24V transformer is the standard specification for stabilizing multi-tap primary configurations in modern heating and cooling equipment.

Key Benefits

• Dual-Primary Flexibility: Supports both 208V and 240V primary taps to match specific site electrical requirements.
• Class 2 Safety Rated: Inherently limited power output to protect sensitive downstream HVAC control boards and thermostats.
• Direct Compatibility: Seamlessly replaces 47K2001 and R39370B001 without the need for mounting modifications.
• Industrial-Grade Construction: Features 1/4 inch quick-connect terminals on the primary and 3/16 inch terminals on the secondary for professional-grade wiring.
• High Efficiency: Minimized core loss ensures the full 40VA rating is available for high-draw contactor coils.

Common Questions

Is the Lennox 47K20 interchangeable with the 47K2001?
Yes, the 47K20 and 47K2001 are the same component. They share identical electrical specifications (208/240V to 24V, 40VA) and physical dimensions, making them 100% interchangeable in Lennox, Armstrong, and Ducane equipment.

What does a 40VA rating mean for my system?
The 40VA (Volt-Ampere) rating defines the maximum power load the transformer can handle. This is sufficient for most standard residential systems, but always verify the total VA draw of your contactors, dampers, and accessories before installation.

Can I use this transformer to replace a 120V primary model?
No. This specific Lennox transformer is built for 208/240V line voltage applications. Applying 120V to the primary will result in inadequate secondary voltage, which will prevent the 24V control circuit from functioning correctly.

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.