Water Heater Efficiency Calculator — Formule
## How to Calculate Water Heater Costs
Water heating is typically the second largest energy expense in a home (14-18% of energy bills).
### Formula
**Daily BTU = Gallons * Temp Rise * 8.33**
**Annual Energy = Daily BTU * 365 / Energy Factor**
### Energy Factors
- Standard gas: 0.60-0.70
- High-efficiency gas: 0.80-0.98
- Electric resistance: 0.90-0.95
- Heat pump water heater: 2.0-4.0
Water heating is typically the second largest energy expense in a home (14-18% of energy bills).
### Formula
**Daily BTU = Gallons * Temp Rise * 8.33**
**Annual Energy = Daily BTU * 365 / Energy Factor**
### Energy Factors
- Standard gas: 0.60-0.70
- High-efficiency gas: 0.80-0.98
- Electric resistance: 0.90-0.95
- Heat pump water heater: 2.0-4.0
Exemple Résolu
50 gal/day hot water, 60F temp rise, 0.92 energy factor, $0.15/kWh.
- Daily BTU: 50 * 60 * 8.33 = 24,990 BTU
- Daily energy with EF: 24,990 / 0.92 = 27,163 BTU
- Annual energy: 27,163 * 365 = 9,914,526 BTU
- Annual cost: 9,914,526 / 3,412 * $0.15 = $436