What troubleshooting step should be taken if a furnace does not ignite properly?

Testing the gas pressure is crucial when troubleshooting why a furnace does not ignite properly. Gas pressure must be within the manufacturer's specified range to ensure that the furnace receives an adequate supply of gas for ignition. If the pressure is too low, it may prevent the gas from igniting, leading to a failure in furnace operation. Conversely, if the pressure is too high, it can create unsafe conditions.

Thus, confirming the gas pressure allows for identifying potential issues with the supply line or the gas valve that might be affecting the ignition process. By ensuring that the gas pressure meets the required levels, technicians can either resolve the issue directly or determine if further investigation is needed, such as checking for blockages or faults in other components of the system.