🔍 Key Concepts

• Boiler heat balance – where energy from burning fuel actually goes • The difference between useful heat (making steam) and losses (wasted heat) • Typical path of flue gases and how boilers try to recover heat

💭 Think About

• Which choice represents heat that is doing the main useful job of the boiler, and which represent heat that is being wasted or not fully recovered? • Think about where hot gases go after leaving the furnace: what parts try to recover that heat, and what part is the final exit where remaining heat is no longer used? • Which option would boiler designers work hardest to reduce because it lowers efficiency and increases fuel consumption?

✅ Before You Answer

• Identify which option clearly describes useful heat for steam production (that is NOT a loss). • Decide which choices describe heat recovery devices (economizer, air heater) vs. actual losses. • Ask: in a real plant, operators worry most about high stack temperature because it indicates the largest single heat loss path.