🔍 Key Concepts

• How heating coils are arranged inside a fuel oil heater and what flows inside them versus outside them • The normal flow path of fuel oil and the path of heating medium (often steam or hot water) • Where leakage would logically appear first when one side of a coil develops a hole

💭 Think About

• Ask yourself: which side of the system is under higher pressure, the heating medium or the fuel oil? How would that affect the direction of any leak? • Think about what surrounds what: is the fuel around the coil, or is the heating fluid around the fuel? If the coil wall fails, where does the leaked fluid go first? • Consider which component (supply line, drain/inspection tank, burner flame) would show a subtle problem earliest, before major combustion changes happen.

✅ Before You Answer

• Verify which fluid (fuel or heating medium) is inside the coil tubes and which fluid is outside the tubes in the heater shell • Confirm which part of the system has higher pressure during normal operation • Consider which of the listed symptoms would be an early indirect sign in the system, rather than a later effect at the burner flame.