On a high efficiency furnace, what component activates the blower fan?

In a high efficiency furnace, the blower fan is typically activated by a relay timer. This component plays a crucial role in ensuring that the furnace operates efficiently by coordinating the timing of the blower fan with the heating cycle.

When the furnace is in operation, the relay timer ensures that the blower fan does not turn on immediately with the ignition of the burner. Instead, it allows the heat exchanger to reach a certain temperature before activating the blower fan. This prevents the fan from blowing cold air into the living space at the start of the heating cycle, which enhances comfort and efficiency. Once the heat exchanger is adequately heated, the relay timer activates the blower fan to circulate the warm air throughout the home.

This functionality is particularly important in high efficiency furnaces, which are designed to maximize heating effectiveness while minimizing energy consumption. By managing the blower fan operation, the relay timer contributes to the overall efficiency of the heating system.