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Water Heater Size Formula:
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The water heater size calculation determines the appropriate First Hour Rating (FHR) for a residential water heater based on household size. This calculation follows Canadian standards for estimating hot water needs.
The calculator uses the simple formula:
Where:
Explanation: The formula estimates the amount of hot water needed during the peak usage hour based on the number of people in the household.
Details: Correctly sizing a water heater is essential for ensuring adequate hot water supply while maximizing energy efficiency. An undersized unit will run out of hot water quickly, while an oversized unit wastes energy and money.
Tips: Enter the number of people living in your household. The calculator will provide the recommended First Hour Rating for your water heater in gallons.
Q1: What is First Hour Rating (FHR)?
A: FHR represents how many gallons of hot water a heater can supply in the first hour of use, starting with a full tank.
Q2: Does this calculation work for tankless water heaters?
A: No, this calculation is specifically for storage tank water heaters. Tankless systems are rated differently based on flow rate and temperature rise.
Q3: Should I consider other factors when choosing a water heater?
A: Yes, consider your peak usage patterns, climate, and whether you have high-flow fixtures. These may require adjustments to the basic calculation.
Q4: Is the 12 gallons per person standard appropriate for all Canadian regions?
A: This is a general guideline that works well for most Canadian households. Colder regions might require slightly higher capacity due to lower incoming water temperatures.
Q5: What if I have a large bathtub or multiple bathrooms?
A: For homes with luxury features like large soaking tubs or multiple bathrooms used simultaneously, you may need to increase the calculated capacity by 10-20%.