Underfired furnace designs alter flame placement and gas circulation. Which of the following outcomes is <em>not</em> typically accomplished by an underfired arrangement?

Introduction / Context:
In an underfired furnace, burners or firing ports direct flames and hot gases below or through passages such that heat reaches the underside of the charge. This improves uniformity and capacity compared with purely overfired layouts. The question asks which claimed benefit does not align with underfired principles.

Given Data / Assumptions:

• Underfiring targets bottom heating to eliminate cold spots.
• Gas circulation can be arranged to protect edges/periphery from over-radiation.
• Capacity per floor area can rise due to improved heat transfer and reduced cycle time.

Concept / Approach:
Underfiring typically enhances effective gas temperature at the locations that matter for the load, increasing overall heat transfer rates. There is no inherent reduction in furnace-gas temperature; if anything, local gas temperatures at the charge surface may be higher or better directed. Therefore, “reduction in the temperature of furnace gases” is not a characteristic benefit of underfired designs.

Step-by-Step Solution:
List typical outcomes: remove bottom cold spot, protect edges, increase throughput per area.Evaluate the statement about lowering gas temperature: inconsistent with underfiring intent.Select it as the item not accomplished.

Verification / Alternative check:
Furnace retrofits introducing underfired or “twin-flame” concepts report improved uniformity and shorter cycles, not reductions in gas temperature; instead, they achieve better temperature distribution at the load surface.

Why Other Options Are Wrong:
Increase in capacity per area: Common via faster heating.Elimination of bottom cold spot: Primary design goal.Periphery protection: Achieved through flame pattern and baffling.

Common Pitfalls:

• Equating “better heat use” with “lower gas temperature.” Efficiency improvements come from distribution and contact, not necessarily cooler gases.
• Ignoring that product temperature control depends on gas circulation design, not merely gas temperature magnitude.

Final Answer:
Reduction in the temperature of furnace gases.