Rock the Gas Heat ESCO Exam 2025 – Fire Up Your Future in HVAC!

The operation of a bi-metal fan switch in a gas furnace is primarily based on temperature control, which means it senses the temperature of the furnace or the surrounding air to operate the blower motor efficiently. When the temperature reaches a certain predetermined level, the bi-metal switch closes, allowing current to flow to the blower motor, which activates it to circulate air throughout the system. Conversely, when the temperature drops below the set point, the bi-metal switch opens, stopping the current flow and deactivating the blower motor.

This mechanism ensures that the blower motor operates only when necessary, improving efficiency and comfort by maintaining optimal temperatures. While current flow is indeed part of the process, the focus on temperature control is what distinguishes the operation of the bi-metal fan switch in this context.

In contrast, other choices such as pressure or voltage variations do not directly relate to the bi-metal fan switch's mechanism. Pressure changes are typically associated with other components in the system, while voltage increases or decreases pertain more to electrical components rather than the temperature regulation function of the bi-metal switch.