Which of the following would you test first if the burners fail to ignite in a furnace system?

In a furnace system where the burners fail to ignite, testing the gas pressure at the manifold is crucial because it directly affects the ability of the burners to light properly. If the gas pressure is inadequate, it could lead to a failure in ignition, as the burners would not receive the necessary fuel to sustain a flame. Ensuring that the gas pressure is within the manufacturer's specifications is essential to determine if there is sufficient gas flow.

Once the gas pressure is established as adequate, technicians can then proceed to check other components, such as the igniter, flame sensor, and thermostat. However, starting with the gas pressure allows for addressing the most critical aspect of combustion first, as without properly managed gas pressure, the system cannot operate effectively regardless of the conditions of the other components.