When checking the input BTUs of a gas appliance, which tool is primarily used?

To determine the input BTUs (British Thermal Units) of a gas appliance, the primary tool used is a gas meter. This instrument measures the volume of gas consumed by the appliance over time. By knowing the volume of gas used and the specific energy content of the gas (often measured in BTUs per cubic foot), the input BTUs can be calculated.

The gas meter provides a direct measurement of gas usage, allowing technicians to ascertain how much gas the appliance is drawing to determine its operational performance and efficiency. This is essential for ensuring appliances are running safely and efficiently.

The other tools, while useful for certain tasks, do not directly measure the input BTUs. A manifold gauge is primarily used for refrigerant pressure checks; a digital thermometer measures temperature, which can help with diagnosing issues but does not provide a direct measurement of gas consumption; and a pressure gauge is used to check gas pressure levels but does not give volume or energy consumption information. Therefore, the gas meter is the most appropriate choice for measuring the input BTUs of a gas appliance.