1. What is Furnace Sizing?

Furnace sizing is the process of determining the appropriate heating capacity (in BTU/hr) needed for a space based on heat loss calculations and system efficiency. Proper sizing ensures optimal performance and energy efficiency.

2. How Does the Calculator Work?

The calculator uses the furnace sizing formula:

Where:

• \( \text{Heat Loss} \) — Total heat loss of the space (BTU/hr)
• \( \text{Efficiency} \) — Furnace efficiency percentage (%)

Explanation: The formula adjusts the required heat output based on the furnace's efficiency to ensure adequate heating capacity.

3. Importance of Proper Furnace Sizing

Details: Correct furnace sizing is crucial for energy efficiency, comfort, and system longevity. Oversized furnaces cycle too frequently, while undersized ones can't maintain desired temperatures.

4. Using the Calculator

Tips: Enter accurate heat loss calculations (from a professional assessment or manual J calculation) and the furnace's AFUE efficiency rating (typically 80-98% for modern furnaces).

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my home's heat loss?
A: Professional energy auditors perform Manual J calculations considering insulation, windows, climate, and other factors for accurate heat loss assessment.

Q2: What's a typical efficiency range for furnaces?
A: Standard efficiency: 80-89% AFUE, High efficiency: 90-98.5% AFUE. Higher efficiency models cost more but save on operating costs.

Q3: Why not just get the largest furnace available?
A: Oversized furnaces short-cycle (turn on/off frequently), reducing efficiency, increasing wear, and creating temperature swings.

Q4: Does furnace size affect installation costs?
A: Larger, higher-efficiency furnaces generally cost more upfront but may save money long-term through lower operating costs.

Q5: Should I consider other factors beyond this calculation?
A: Yes - ductwork design, climate zone, home layout, and future insulation improvements should all be considered in final sizing decisions.