What safety control is used to protect high-efficiency, noncondensing furnaces from high stack temperatures?

High-efficiency, noncondensing furnaces are designed to operate with specific temperature thresholds, and stack temperature protection is crucial for their safe operation. The correct answer highlights the role of vent control in maintaining safe conditions within such HVAC systems.

Vent control includes mechanisms that monitor the temperature of the exhaust gases as they exit the furnace. If the temperatures exceed safe operating levels, the vent control system can either adjust the operation of the furnace or shut it down, preventing potential overheating and damage to the furnace and associated venting systems. This is particularly important in noncondensing models, where excessively high stack temperatures can lead to inefficiency and pose safety hazards.

While other controls like pressure control and limit control may contribute to overall safety and efficiency, vent control specifically targets the management of exhaust temperatures, making it the most relevant and effective safety control for this particular scenario.