How to Calculate Water Heater Sizing
What is Water Heater Sizing?
Water Heater Sizing Calculator helps contractors and tradespeople accurately size, spec, and estimate materials and systems.
Formula
Required GPH = Peak Hour Demand × Recovery Efficiency
Step-by-Step Guide
- 1Estimate peak hour usage based on household size and habits
- 2Apply the formula using your project measurements
- 3Add required safety factors or waste allowances per code
Worked Examples
Input
4 person household, peak 80 gallons/hr needed
Result
Size for 80 GPH recovery or 50-gallon tank
Common Mistakes to Avoid
- ✕Not applying code-required safety factors or derating
- ✕Forgetting to account for waste and cut losses in material estimates
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