Question

The difference between 80 percent efficiency furnaces and 90 percent efficiency furnaces is that 90 percent efficiency

furnaces:
Select one:
A. Use more combustion air per 1,000 BTU firing rate.
B. Burn more gas to increase the heat exchanger temperatures.
C. Use more efficient air filters.
O D. Have an extra recuperative heat exchanger that condenses water out of the flue gas.

Answer 1

The difference between 80 percent efficiency furnaces and 90 percent efficiency furnaces is that 90 percent efficiency furnaces have an extra heat exchanger that condenses water out of the flue gas, increasing their efficiency.

Step-by-step explanation:

The difference between 80 percent efficiency furnaces and 90 percent efficiency furnaces is that 90 percent efficiency furnaces use an extra recuperative heat exchanger that condenses water out of the flue gas. This extra heat exchanger helps to extract more heat from the combustion process, resulting in higher efficiency. It is not related to the amount of combustion air, the gas burned, or the air filters used.

Learn more about Efficiency of furnaces