When setting up a gas furnace, what safety device should be checked before operation?

When setting up a gas furnace, it is critical to check all safety devices to ensure safe and efficient operation. Each of these components plays a vital role in protecting the furnace and preventing hazardous situations.

The high-limit switch is important because it prevents the furnace from overheating. If the temperature exceeds a certain threshold, this switch will shut off the burners to protect the furnace from damage and potential fire hazards.

The flame rollout switch is designed to shut off the furnace if it detects that flames are escaping from the combustion chamber, which can occur due to blockages or malfunctions in the flue system. This switch is essential for preventing flue gas from entering the living space, which can be dangerous.

The pressure switch monitors the pressure within the furnace and ensures that there is adequate airflow. If the pressure is not within acceptable levels, it indicates a problem that could hinder the furnace's operation or lead to unsafe conditions.

By checking all of these safety devices before operation, technicians can ensure that the furnace operates safely and efficiently. This comprehensive approach underscores the importance of safety in gas furnace operation, making the option to check all devices the most responsible choice.