OEM Lennox Transformer — 10P17

The genuine OEM Lennox 10P17 transformer steps down incoming line voltage to the 24-volt low-voltage control power that runs your Lennox thermostat, control board, relays, and gas valve. It is the heart of the control circuit — without it, none of the low-voltage components can operate. This transformer is built to Lennox specifications for the correct primary and secondary voltages and VA rating.

Common failure symptoms include a completely dead thermostat, a system that will not respond to any call for heat or cooling, a tripped or blown low-voltage fuse, an overheated or humming transformer, or a burnt smell from the control compartment. A shorted 10P17 can also repeatedly blow the board fuse until it is replaced.

Why OEM matters: The 10P17 must deliver the exact secondary voltage and current capacity your Lennox control board and accessories expect. An OEM transformer ensures proper VA output, correct terminal configuration, and safe, code-compliant operation — preventing the brownouts and premature fuse failures that under-rated aftermarket transformers commonly cause. Installing the factory part restores reliable control power and protects the rest of your low-voltage circuit.