Which instrument is used to check the gas pressure of a furnace?

A manometer is specifically designed to measure the pressure of gases in various applications, including checking the gas pressure of a furnace. It provides a visual reading of pressure in inches of water column (in wc) or millibars, depending on the type of manometer used. This instrument allows technicians to ensure that the gas pressure is within the manufacturer's specified range for safe and efficient operation of the furnace.

In contrast, a digital multimeter is typically used for measuring electrical parameters such as voltage, current, and resistance rather than gas pressure. A pressure regulator, while crucial in regulating and controlling the pressure of the gas supplied to the appliance, does not measure pressure itself; instead, it adjusts and maintains the pressure within designated parameters. A Bourdon gauge, which is an instrument that measures pressure, is generally used in plumbing and industrial applications, but a manometer is preferred for precision measurements in gas applications within HVAC systems.