A furnace installation design explicitly requires 600 cfm of combustion-air supply. Commissioning measures 450 cfm. How much additional airflow is needed to meet that specified target?
- A50 cfm
- 150 cfm
- C450 cfm
- D1,050 cfm
Where to look it up
Explicit exercise assumptions; not a universal code requirement.
Why B is correct
The shortfall is 600 − 450 = 150 cfm. The target is supplied by this exercise; it is not inferred from furnace input or presented as a universal fuel-gas rule.