1. What is a Water Heater Efficiency Calculator by Age?

Definition: This calculator estimates the current efficiency of a water heater based on its rated efficiency, degradation rate, and age.

Purpose: It helps homeowners and professionals assess how much a water heater's performance has declined over time and when replacement might be needed.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( \eta \) — Current efficiency (%)
• \( \eta_{\text{rated}} \) — Manufacturer's rated efficiency (%)
• \( D \) — Degradation rate (decimal per year)
• \( \text{Age} \) — Age of water heater (years)

Explanation: The rated efficiency is reduced by the degradation rate multiplied by the heater's age to account for normal wear and tear.

3. Importance of Efficiency Calculation

Details: Tracking efficiency decline helps estimate energy costs, determine maintenance needs, and decide when replacement becomes cost-effective.

4. Using the Calculator

Tips: Enter the manufacturer's rated efficiency (%), typical degradation rate (default 0.015/year), and the heater's age in years. All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical degradation rate for water heaters?
A: Most water heaters degrade at 1-2% per year (0.01-0.02 in decimal form), with gas heaters typically degrading faster than electric ones.

Q2: Where can I find the rated efficiency?
A: Check the yellow EnergyGuide label on your water heater or the manufacturer's specifications.

Q3: Does this account for maintenance issues?
A: No, this calculates normal degradation. Poor maintenance or hard water can cause faster efficiency loss.

Q4: When should I consider replacing my water heater?
A: Consider replacement when efficiency drops below 70% of rated value or when annual repair costs exceed replacement cost.

Q5: Can efficiency go below 0%?
A: No, the calculator automatically limits results to a minimum of 0%.