In standard gas appliances, how is combustion air typically supplied?

In standard gas appliances, combustion air is typically supplied from inside the building to ensure that there is a sufficient supply of air for combustion to occur efficiently. This method allows the appliances, such as furnaces or water heaters, to use the ambient air present in the room or the space in which they are installed.

This approach is often suitable for smaller appliances where the volume of air in the room is adequate to support combustion without negatively affecting air quality or appliance performance. Appliances designed for indoor use rely on the surrounding environment to provide the necessary oxygen for combustion. Additionally, this method simplifies installation since there is no need for external venting systems or additional components to draw in air from outside.

Using interior air has its limitations, especially when considering air quality and efficiency during operation, which may require a careful balance to prevent potential issues with backdrafts or insufficient air supply in tightly sealed spaces.