1. What is the AC Furnace Size Calculation?

The AC furnace size calculation estimates the required heating capacity (in BTU/h) for a space based on its area. This simple rule of thumb helps determine appropriate furnace sizing for residential applications.

2. How Does the Calculator Work?

The calculator uses the basic furnace sizing formula:

Where:

• \( BTU/h \) — British Thermal Units per hour (heating capacity)
• \( Area \) — Floor area in square feet
• \( 35 \) — Standard multiplier for moderate climates

Explanation: The formula assumes about 35 BTU per square foot for heating in typical conditions. This may need adjustment for very cold or very warm climates.

3. Importance of Proper Furnace Sizing

Details: Correct furnace sizing is crucial for energy efficiency, comfort, and system longevity. An oversized furnace will short-cycle, while an undersized one won't adequately heat the space.

4. Using the Calculator

Tips: Enter the total area to be heated in square feet. For irregular spaces, calculate the total floor area. The result shows the approximate BTU/h capacity needed.

5. Frequently Asked Questions (FAQ)

Q1: Is 35 BTU/sq.ft always appropriate?
A: This is a general guideline. Colder climates may require 40-45 BTU/sq.ft, while milder climates may need only 30.

Q2: What factors affect furnace sizing beyond area?
A: Ceiling height, insulation quality, window area, climate zone, and home orientation all impact heating requirements.

Q3: Should I round up the calculated size?
A: Furnaces come in standard sizes. Choose the next available size if your calculation falls between standard capacities.

Q4: How does this differ from AC cooling capacity?
A: Cooling typically requires 20 BTU/sq.ft, less than heating, because heat loss is generally greater than heat gain.

Q5: When should I consult a professional?
A: For precise calculations, especially in extreme climates, poorly insulated homes, or commercial applications.