What is a draft gauge primarily used for?

A draft gauge is primarily used for testing chimney draft, which is essential for determining the efficiency and safety of combustion appliances. The draft refers to the flow of air and combustion gases in the chimney system. Proper draft is necessary to ensure that flue gases are effectively vented outdoors, preventing harmful emissions from entering living spaces.

When assessing the draft, technicians look for an adequate pressure difference between the inside of the chimney and the outside environment. This measurement helps ensure that the appliance operates safely and efficiently, as insufficient draft can lead to poor combustion and increased production of carbon monoxide and other harmful pollutants.

In the context of this question, monitoring fuel levels, measuring air pressure, and assessing carbon monoxide levels do not directly relate to the primary function of a draft gauge. Each of those tasks may be addressed by different instruments specialized for those particular measurements.