Which type of dampers should not be installed in combustion air ducts?

The installation of manual dampers in combustion air ducts is not recommended due to safety and operational concerns. Combustion air ducts are critical for ensuring adequate airflow to fuel-burning appliances, which require a consistent and reliable supply of air for efficient and safe operation.

Manual dampers can pose a risk because they require manual adjustment to open or close, which may be forgotten or left in the wrong position during operation. This could lead to insufficient air supply, negatively impacting combustion efficiency, and potentially leading to the production of hazardous emissions such as carbon monoxide. Ensuring that combustion appliances receive the proper amount of combustion air is essential for their safe operation, making the reliability of the damper mechanism crucial.

In contrast, automatic dampers, positive pressure dampers, and smoke dampers are designed with features that enhance their operation and responsiveness to changing conditions, ensuring that air supply is managed safely and effectively without the need for manual intervention.