How much flue gas is produced from a 60,000 BTU/h Category I fan-assisted natural gas furnace operating with 50% excess air?

To determine the amount of flue gas produced by a 60,000 BTU/h Category I fan-assisted natural gas furnace operating with 50% excess air, understanding the combustion process is crucial.

First, we need to calculate the theoretical air required for complete combustion. Natural gas has a heat value of approximately 1,000 BTU per cubic foot. For a 60,000 BTU/h furnace, the amount of natural gas consumed can be calculated by dividing the total BTU output by the BTU content of the gas:

[

\text{Gas Flow Rate} = \frac{60,000 \text{ BTU/h}}{1,000 \text{ BTU/Cu Ft}} = 60 \text{ Cu Ft/h}

]

Next, during combustion, each cubic foot of natural gas requires approximately 10 cubic feet of air for complete combustion. Thus, the theoretical air required can be calculated:

[

\text{Theoretical Air} = 60 \text{ Cu Ft/h} \times 10 = 600 \text{ Cu Ft/h}

]

Now, considering the operation with 50% excess air, we need to calculate the actual air used, which is:

[