How is draft typically measured?

Draft is a measure of the pressure difference that drives airflow in a system, particularly in heating and ventilating, as well as in combustion applications like boilers or furnaces. It reflects how effectively air is drawn into a system, which is crucial for the efficient operation of these devices.

The correct unit for measuring draft is in inches of water. This measurement indicates the height of a column of water that would exert the same pressure as the draft being measured. It’s a practical unit, as it allows engineers to easily relate the pressure changes in air to a manageable and interpretable quantity. For example, if you have a draft measurement of 1 inch of water, it means the pressure difference is equivalent to the pressure exerted by a 1-inch column of water.

The other choices are not suitable for measuring draft. Degrees Celsius is a unit of temperature and does not relate to pressure differences. Pounds per square inch (psi) measures pressure in a different context, typically for gases or liquids, but not in the specific application of draft where air pressure differentials are involved. Feet of pressure could theoretically relate to pressure measurement, but it’s not the standard measurement for draft and would complicate conversions and applications in stationary engineering contexts. Thus, the focus on