What are the three functions performed by draft hoods?

Draft hoods serve critical functions in the safe operation of appliances such as gas-fired water heaters or furnaces. Their primary role is to ensure proper ventilation and combustion efficiency within a system.

One key function is to balance draft, which helps maintain the appropriate air pressure within the venting system. This balance is crucial for efficient combustion and helps prevent dangerous backdrafts that could lead to the release of harmful gases into living spaces.

Another essential function of draft hoods is providing dilution air. This involves mixing fresh air with exhaust gases, which helps lower the temperature and concentration of pollutants before they are expelled through the venting system. Providing dilution air is vital for minimizing the impact of combustion byproducts on indoor air quality.

Lastly, draft hoods allow for spillage, which refers to the safe discharge of combustion gases when there is a malfunction or a change in pressure. This function helps direct any harmful gases away from the living area and into the atmosphere, thereby protecting occupants' health and safety.

In contrast, the other options focus on functions that do not accurately reflect the roles of draft hoods. For example, increasing pressure or regulating temperature are not functions of draft hoods. Understanding these key roles highlights the importance of proper installation and maintenance of drafting systems