What must be checked if a gas furnace fails to ignite properly?

When a gas furnace fails to ignite properly, it is essential to check multiple components to determine the root cause of the issue. Each of the options provided plays a critical role in the ignition process of a gas furnace.

First, the color of the flame is significant because it can indicate combustion efficiency and safety. An improper flame color could suggest incomplete combustion or the presence of contaminants, which can lead to unsafe operating conditions.

Second, the electrical connections must be examined since the ignition system relies on electrical components, such as ignition electrodes and gas valves, to function correctly. If there are loose or corroded connections, it may prevent the system from igniting.

Third, checking the gas supply pressure is crucial because insufficient pressure can result in inadequate fuel delivery to the burners, which can hinder ignition. If the pressure is too low, the furnace may fail to start even if everything else is functioning properly.

Since each of these factors contributes to the ignition of the gas furnace, it is necessary to assess all of them to accurately diagnose the problem when ignition issues arise. This comprehensive approach ensures that technicians can identify any possible faults and ensure safe and efficient operation of the furnace.