Which control is used to protect against a plugged heat exchanger in high-efficiency, non-condensing furnaces?

The flame roll-out control is utilized to protect against a plugged heat exchanger in high-efficiency, non-condensing furnaces by monitoring the temperature of the combustion chamber. If the heat exchanger becomes obstructed, it can cause excessive heat buildup, which may lead to the flame rolling out from the burner area. The flame roll-out control detects this condition by triggering if temperatures exceed a certain threshold, ensuring that the system shuts down to prevent potential damage or fire hazards.

This control is essential for maintaining safety in furnace operation, as it directly addresses the risks associated with overheating due to blockages in the heat exchanger. Other controls in the options listed serve different functions, such as monitoring pressure or draft conditions, but they do not specifically address the issue of flame rollout caused by a plugged heat exchanger.