In the described HRT boiler, what is the total heating surface?

In the described HRT boiler, what is the total heating surface?

• A. 3125 sq ft
• B. 6000 sq ft
• C. 4167 sq ft
• D. 5200 sq ft

Answer: (C)

Total heating surface is the combined area where heat from the combustion gases is transferred to the water or steam inside the boiler. In an HRT boiler, you figure it by adding every water-containing surface’s area: every tube surface (outer circumference times length) for all tubes, plus any other water-contact surfaces such as water walls or headers that contribute heat transfer. For each tube type, calculate A = π × D × L per tube and multiply by how many tubes of that type, then sum across all types and add the areas of other water-surfaces. When you include all of these correctly from the diagram, the total comes to 4167 square feet. That’s the correct total heating surface because it accounts for every area actually in contact with water and exchanging heat. If you only counted part of the tubes or added non-water-contact surfaces, you’d get a value that’s not the full total.

Total heating surface is the combined area where heat from the combustion gases is transferred to the water or steam inside the boiler. In an HRT boiler, you figure it by adding every water-containing surface’s area: every tube surface (outer circumference times length) for all tubes, plus any other water-contact surfaces such as water walls or headers that contribute heat transfer. For each tube type, calculate A = π × D × L per tube and multiply by how many tubes of that type, then sum across all types and add the areas of other water-surfaces. When you include all of these correctly from the diagram, the total comes to 4167 square feet. That’s the correct total heating surface because it accounts for every area actually in contact with water and exchanging heat. If you only counted part of the tubes or added non-water-contact surfaces, you’d get a value that’s not the full total.