Gas Fitter Practice Test

If the gas valve (thermostat side) to common terminals read 0V, what is likely the open component?

1. Gas valve coil

2. Thermostat

3. High limit

4. Transformer

The correct answer is: Gas valve coil

The gas valve coil is the most likely component that could be open when the thermostat side reads 0V. A reading of 0V indicates that there is no voltage being supplied to the coil, which can happen if the coil has become open, meaning there is a break in the winding of the coil that prevents electrical current from flowing through it. This disruption stops the gas valve from being able to open, as the coil needs to be energized to operate the valve mechanism. In the context of the system, the thermostat is typically responsible for providing the voltage signal to the gas valve coil to energize it. If the thermostat is functioning properly and providing the appropriate signal but the coil is open, this would lead to a 0V reading at the terminals. Similarly, a high limit switch, if it were open, would prevent the circuit from being completed but would likely lead to a different voltage reading based on its condition rather than a direct 0V from the gas valve itself. The transformer provides the necessary voltage for the operation of various system components, so if it were malfunctioning, the symptoms would be more systemic rather than localized to just the gas valve coil. Hence, the most direct and relevant cause of a 0V condition specifically at