How is the blower motor typically started in an oil-fired furnace?

In an oil-fired furnace, the blower motor is typically started by temperature. This means that the motor activates based on the heat needs of the system, particularly when the furnace reaches a certain temperature threshold. As the furnace heats up, a thermostat or limit switch senses this change and signals the blower motor to turn on, allowing air to circulate through the system and distribute warmth throughout the space.

This method of operation is efficient because it ensures that the blower only runs when it's needed – during and after the heating cycle – which helps to maintain a comfortable temperature while also conserving energy. Using temperature as the trigger for the blower motor aligns with the overall design and purpose of the heating system, which is to respond dynamically to temperature changes in the environment.