What is the air that is mixed with flue gases in a draft hood called?

The air that mixes with flue gases in a draft hood is referred to as dilution air. This term describes the process of using ambient air to lower the concentration of combustion gases, which can include harmful substances such as carbon monoxide and other particulates, thereby improving safety and efficiency in ventilation systems.

In a typical heating system, when combustion occurs, flue gases, which represent the byproducts of that combustion, are expelled from the system. The introduction of dilution air helps to ensure that these gases are within safe limits before they are vented into the atmosphere. This mixing is crucial not only for environmental safety but also for the proper functioning of appliances connected to vent systems, as it helps to regulate pressure and reduce the likelihood of backdrafting.

Understanding this concept and its significance in the context of ventilation and combustion processes in mechanical systems is essential for anyone working in HVAC or related fields, as it emphasizes the importance of managing air quality and emission levels effectively.