NATE Gas Heating Practice Exam

What will happen when a jumper wire is placed between the "R" terminal and the "W" terminal on a thermostat sub-base?

1. Gas valve

2. Indoor fan motor

3. Outdoor fan motor

4. Compressor

The correct answer is: Gas valve

When a jumper wire is placed between the "R" terminal (often representing the power supply from the transformer) and the "W" terminal (which typically controls the heating function), it effectively creates a direct connection that activates the heating system. This action sends a signal to the gas valve to open, allowing gas to flow to the burner and produce heat. This process is fundamental for the operation of gas-fired heating systems. By connecting these two terminals, the thermostat mimics a demand for heat, causing the heating system to initiate its operation. The gas valve, therefore, is the correct answer because it is directly influenced by this jumper configuration and plays a critical role in starting the heating process. The other components listed in the choices, such as the indoor fan motor, outdoor fan motor, and compressor, are related to other functions in heating, ventilation, and air conditioning (HVAC) systems, but are not engaged directly by this specific jumper connection meant to signal the heating cycle. Thus, they do not respond to the action taken with the jumper wire placed between the “R” and “W” terminals.