Gas pressure in a furnace is usually measured in what unit?

Gas pressure in a furnace is typically measured in inches of water column (in. WC). This unit is particularly relevant because it effectively represents low-pressure environments like those found in many heating applications, including residential furnaces. The water column measurement takes into account the pressure exerted by a column of water, which is useful in scenarios where the pressures involved are relatively low, such as in gas-burning equipment.

Using inches of water column allows technicians and HVAC professionals to accurately assess and adjust the gas pressure for optimal performance and safety. It's crucial in ensuring that the furnace operates efficiently and avoids issues such as incomplete combustion, which can lead to unsafe conditions.

The other units mentioned, like PSI (pounds per square inch), Bar, and KPa (kilopascals), are more commonly used in different applications or for measuring higher pressures. These units are not suitable for the typical operating pressures found in residential gas furnaces, making inches of water column the most appropriate choice for this context.