Gas Fitter Practice Test

If a customer reports the pilot light goes out intermittently, and the millivolt test shows a steady 14mV while the magnet drops at 4mV, what should the technician do next?

1. Replace the gas valve

2. Clean and adjust the pilot and burners

3. Replace the thermocouple

4. Check for down draft or pilot position

The correct answer is: Check for down draft or pilot position

When a customer reports that the pilot light goes out intermittently, and the millivolt test indicates a steady 14mV while the magnet drops at 4mV, it is crucial to understand the implications of these readings. The millivolt reading of 14mV suggests that the thermocouple is functioning properly, generating enough voltage to keep the gas valve energized under normal conditions. However, the fact that the magnet drops at 4mV indicates that while the thermocouple works, there may be an issue affecting the stability of the pilot flame. The next step, which is to check for down drafts or pilot position, is essential because external factors can impact the pilot flame stability. A down draft, for example, could blow out the pilot light intermittently or cause it to burn improperly, leading to an unstable flame. Ensuring that the pilot light is positioned correctly and shielded from drafts is vital for reliable operation. By addressing potential environmental issues, the technician can identify if the pilot flame instability is due to external factors rather than internal component failures like the gas valve or thermocouple. This method of troubleshooting is effective as it targets the root cause of the intermittent pilot outage before resorting to replacing components, which