Which measurement indicates pressure when dealing with gas appliances?

The correct measurement for indicating pressure when dealing with gas appliances is represented in inches of water column (In W.C.). This unit is commonly used in the context of low-pressure gas systems, such as those found in residential gas appliances.

Inches of water column allows for accurate measurement of very low pressures, which is critical in ensuring proper operation of gas appliances like furnaces, water heaters, and stoves. It allows technicians to gauge the pressure accurately to ensure appliances function efficiently and safely.

Psig (pounds per square inch gauge) and Psia (pounds per square inch absolute) measure pressures that are typically too high for standard gas appliances, as they are more suited for industrial applications or systems where higher pressures can be expected. Although Bar is also a unit of pressure, it is less commonly used in North American gas appliance contexts compared to inches of water column, making it less relevant for this specific application.