What are the two components of draft in combustion systems?

In combustion systems, draft is a key factor influencing the efficiency and safety of the combustion process. The two primary components of draft are chimney draft and over-fire draft.

Chimney draft refers to the upward movement of combustion gases through the chimney, driven by the difference in temperature between the hot gases and the cooler air outside. This draft is essential for venting combustion products safely out of the structure and ensuring that fresh air is drawn into the combustion chamber.

Over-fire draft, on the other hand, occurs when there is excessive airflow into the combustion chamber, which can lead to inefficiency in the combustion process and potentially hazardous conditions if not managed properly. It is an important aspect to monitor, as it affects the performance of heating appliances and can influence the overall balance of the combustion system.

Both components work together to ensure that combustion occurs effectively, with proper exhaust of gases and intake of air, thus keeping the system operating safely and efficiently. Understanding these components helps in diagnosing and improving combustion system performance, making them fundamental concepts for those involved in building performance and energy analysis.