Gas Fitter Practice Test

How is the external bypass valve set?

1. Shutting off the pump

2. Viewing the burner flame size

3. Determining the appliance input

4. Determining the temperature rise across the appliance

The correct answer is: Determining the temperature rise across the appliance

The external bypass valve is set by determining the temperature rise across the appliance. This process involves measuring the temperature of the flue gases as they exit the appliance and comparing it with the temperature of the combustion air entering. The objective is to ensure that the appliance operates efficiently and safely, achieving the proper temperature differential. Setting the bypass valve accurately is crucial because it helps maintain the right balance of air and fuel, ensuring that combustion occurs effectively. If the temperature rise is too high, indicating insufficient airflow or excess fuel, adjustments need to be made to the bypass valve to optimize performance and prevent issues like overheating or inefficient combustion. Therefore, focusing on the temperature rise provides a clear metric for the functioning of the gas appliance and ensures safe operation.