What is the function of a transformer in a gas furnace?

In a gas furnace, the function of a transformer is to reduce line voltage. Furnaces typically operate on low-voltage control circuits, usually 24 volts, for their ignition systems, thermostats, and most control functions. The transformer takes the higher line voltage (such as 120 volts or 240 volts) from the electrical supply and steps it down to a safer, lower voltage suitable for the furnace's components.

This step-down in voltage is crucial because it allows devices that cannot handle higher voltages to operate safely and effectively. Low-voltage systems also minimize risks associated with electrical shocks and improve safety in residential installations.

While the other functions mentioned in the options, such as increasing voltage, regulating temperature, or acting as a safety shutoff, are essential in other contexts within HVAC systems, they do not describe the primary role of the transformer in a gas furnace.