What should a technician check when a gas valve fails to open but other conditions are met?

When a gas valve fails to open despite other conditions being met, the limit switch is an important component to check. The limit switch serves as a safety mechanism that monitors the temperature within the furnace or heating system. If the system detects unsafe operating conditions, such as overheating, the limit switch will interrupt the operation of the gas valve to prevent further escalation of the problem.

In this scenario, if the limit switch is faulty or stuck open due to incorrect temperature readings or external factors, it may prevent the gas valve from receiving the necessary signal to open. As a result, verifying the functionality of the limit switch is crucial for ensuring that that gas valve can operate correctly when conditions are safe.

Other components, such as thermostat wiring, the gas supply line, and activation voltage, are certainly relevant to the overall operation of the heating system. However, if the gas valve is receiving the correct signals and still fails to open, checking the limit switch becomes a priority to ensure safety protocols are in place and to diagnose the issue accurately.