Which condition is listed as a potential heater trip cause?

• A. High fuel gas pressure
• B. High flame speed
• C. Adequate fuel supply
• D. High ambient humidity

Answer: (A)

Safety interlocks in heater operation protect against abnormal fuel delivery. When fuel gas pressure rises above the safe limit, the control system will trip to shut off fuel flow and prevent unsafe combustion or overheating. This prevents potential damage to the burner and furnace and reduces the risk of a hazardous release.

High fuel gas pressure is the best answer because it directly threatens safe operation and is a standard trigger for a heater trip. The other factors described—flame speed, having an adequate fuel supply, or high ambient humidity—do not by themselves represent a direct trip condition in typical heater protection logic.