Rock the Gas Heat ESCO Exam 2025 – Fire Up Your Future in HVAC!

An overfired furnace in a gas heating system can be attributed primarily to a gas pressure issue or a malfunctioning gas valve. Overfiring occurs when excess fuel is introduced into the combustion process, leading to elevated combustion temperatures and pressures.

When the gas valve fails to regulate gas flow properly, it can cause too much gas to be delivered to the furnace. This situation may arise if the valve is stuck open, improperly adjusted, or malfunctioning in its ability to modulate the gas supply based on the furnace's needs. Additionally, an incorrect gas pressure setting—either too high from the incoming supply or a failure in the pressure regulation—can similarly lead to an overfired condition.

While factors like a malfunctioning thermostat might influence overall system performance, they do not directly cause overfiring. Regular maintenance inspections are crucial for identifying potential issues before they escalate, and a functioning gas valve is essential for proper operation, but only if they are optimized correctly. Therefore, the primary causes of overfiring directly link to the gas pressure management and the condition of the gas valve.