Gas Heat ESCO Practice Exam

A homeowner complained that his furnace makes a loud bang upon ignition. The technician checks the gas pressure and finds 3.2 in. WC at the manifold. The technician should:

1. Check for water in the gas line

2. Check thermostat settings

3. Check supply gas pressure

4. Replace the gas valve

The correct answer is: Check supply gas pressure

The correct approach for addressing a loud bang upon ignition in a furnace involves checking the supply gas pressure. A loud bang is often an indication of delayed ignition, which can occur when too much gas accumulates in the combustion chamber before ignition takes place. This situation can be exacerbated by improper supply gas pressure. Ensuring that the gas pressure is within the manufacturer's specifications is crucial for the safe and efficient operation of the furnace. If the supply pressure is too low, it might not ignite properly or quickly, while too high a pressure could cause excessive gas flow, leading to the symptoms described. Therefore, confirming that the supply gas pressure is correct is an essential step in diagnosing the problem. Addressing water in the gas line, checking thermostat settings, or replacing the gas valve are not the most immediate steps to take for this specific issue. These actions may be relevant in other contexts, but focusing on gas pressure to prevent delayed ignition is key to resolving the homeowner's complaint.