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Electric Water Heater Sizing Formula:
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Electric water heater sizing is the process of determining the appropriate tank capacity needed to meet a household's hot water demands. Proper sizing ensures adequate hot water supply while maximizing energy efficiency.
The calculator uses the sizing formula:
Where:
Explanation: The formula calculates the appropriate tank size by applying a 75% factor to the peak hourly demand, which accounts for recovery rates and ensures adequate hot water supply.
Details: Correct water heater sizing is essential for energy efficiency, cost savings, and ensuring consistent hot water supply. An undersized unit will run out of hot water quickly, while an oversized unit wastes energy and increases operating costs.
Tips: Enter your peak hourly hot water demand in gallons per hour. This value represents the maximum amount of hot water your household uses during the busiest hour of the day.
Q1: How do I determine my peak hourly demand?
A: Calculate the total gallons of hot water used during your busiest hour by adding up the flow rates of all fixtures used simultaneously.
Q2: Why is the sizing factor 0.75 for electric water heaters?
A: This factor accounts for the recovery rate of electric water heaters and ensures the unit can meet demand while maintaining energy efficiency.
Q3: Does this calculation work for all household sizes?
A: This is a general calculation that works for most households. Very large homes or commercial applications may require additional considerations.
Q4: Should I round up or down when selecting a water heater size?
A: It's generally recommended to round up to the nearest available standard size to ensure adequate capacity.
Q5: Are there other factors to consider when selecting a water heater?
A: Yes, consider energy efficiency ratings, available space, installation requirements, and whether a tankless system might be more appropriate for your needs.