1. What is AFUE?

AFUE (Annual Fuel Utilization Efficiency) is a measure of a gas furnace's efficiency in converting fuel to heat over a typical year. It represents the percentage of fuel that is converted to usable heat.

2. How Does the Calculator Work?

The calculator uses the AFUE equation:

Where:

• \( Heat Output \) — Useful heat produced by the furnace (BTU)
• \( Fuel Input \) — Total fuel energy consumed by the furnace (BTU)

Explanation: The equation calculates the efficiency percentage by comparing the useful heat output to the total fuel input.

3. Importance of AFUE Calculation

Details: AFUE rating is crucial for evaluating furnace efficiency, comparing different models, estimating energy costs, and making informed purchasing decisions for heating systems.

4. Using the Calculator

Tips: Enter both heat output and fuel input values in BTU. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is considered a good AFUE rating?
A: Modern high-efficiency furnaces typically have AFUE ratings of 90-98%, while standard efficiency models range from 80-89%.

Q2: How does AFUE differ from SEER?
A: AFUE measures furnace heating efficiency, while SEER (Seasonal Energy Efficiency Ratio) measures air conditioner cooling efficiency.

Q3: Can AFUE be greater than 100%?
A: No, AFUE cannot exceed 100% as it represents the percentage of fuel converted to usable heat.

Q4: How often should AFUE be calculated?
A: AFUE is typically calculated during furnace testing and certification. Homeowners should refer to manufacturer specifications rather than calculating it themselves.

Q5: Does AFUE account for heat loss in ductwork?
A: No, AFUE only measures the furnace's efficiency at converting fuel to heat, not distribution efficiency through ductwork.