What is the simplest way to measure draft in a system?

Measuring draft in a system is crucial for ensuring proper airflow and combustion efficiency, particularly in boilers, furnaces, and exhaust systems. A U-tube manometer is considered the simplest and most effective method for measuring draft due to its straightforward design and operation.

The U-tube manometer consists of a transparent tube bent in the shape of a "U," with one side connected to the area where the draft needs to be measured and the other side open to the atmosphere. The difference in fluid levels between the two sides of the manometer indicates the pressure difference, providing a clear and direct measurement of draft in inches of water column (in WC) or other units of pressure.

This method is not only easy to read but also requires minimal setup and is quite accurate for low-pressure measurements, which are typical in draft situations. In contrast, the other devices listed, like Bourdon tube devices, flexible diaphragm devices, and bellows measuring devices, are more complex and may require calibration or may not be as directly suitable for measuring the relatively low pressures found in draft scenarios.