How is draft typically measured in heating systems?

Draft in heating systems, particularly those that involve combustion, is primarily measured in inches of water column using a manometer or U gauge. This method effectively measures the pressure difference created by the flow of air and exhaust gases, which is essential for ensuring proper combustion and efficient operation of the system.

A manometer is sensitive enough to detect small changes in pressure that are crucial for maintaining safe and effective draft levels. Measuring draft in inches of water column allows technicians to determine whether the system is operating within the correct parameters. If the draft is too low, it may lead to poor combustion and the potential for hazardous conditions, while excessive draft can also cause issues like increased wear on the system components.

Using pressure gauges in pounds per square inch is not suitable for measuring draft because it is not designed for the low-pressure differential typically found in heating systems. Thermometers measure temperature, not pressure or airflow, and calculating airflow does not provide a direct measure of the draft produced by the system. Thus, the most accurate and effective method for measuring draft in heating systems remains the use of inches of water column with a manometer or U gauge.