1. What is Natural Gas Furnace Sizing?

Natural gas furnace sizing involves calculating the appropriate input BTU capacity needed to meet a specific heating output requirement based on the furnace's efficiency. Proper sizing ensures optimal performance and energy efficiency.

2. How Does the Calculator Work?

The calculator uses the furnace sizing formula:

Where:

• \( BTU Input \) — Required furnace input capacity (BTU/hr)
• \( Output Needed \) — Desired heating output (BTU/hr)
• \( Efficiency \) — Furnace efficiency percentage (%)

Explanation: This formula calculates the input BTU requirement by accounting for the furnace's efficiency, ensuring the unit can deliver the needed output.

3. Importance of Proper Furnace Sizing

Details: Correct furnace sizing is crucial for energy efficiency, comfort, and system longevity. Oversized furnaces short-cycle, while undersized units struggle to maintain temperature.

4. Using the Calculator

Tips: Enter furnace efficiency as a percentage (e.g., 80 for 80%) and the required heating output in BTU/hr. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is typical furnace efficiency?
A: Standard efficiency furnaces are 80-85%, while high-efficiency models can reach 90-98% AFUE.

Q2: How do I determine output needed?
A: Output needed is based on heat load calculation considering home size, insulation, climate, and other factors.

Q3: What happens with wrong sizing?
A: Oversized furnaces waste energy and reduce comfort; undersized furnaces can't maintain desired temperatures.

Q4: Should I round up the calculated BTU?
A: It's recommended to round to the nearest standard furnace size available from manufacturers.

Q5: Is this calculation for new installations only?
A: This applies to both new installations and replacement units where heating requirements are known.