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Hot Water Tank Size Formula:
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Hot water tank sizing is the process of determining the appropriate capacity of a water heater based on peak hour demand. Proper sizing ensures adequate hot water supply while maximizing energy efficiency.
The calculator uses the formula:
Where:
Explanation: The formula calculates the minimum tank size needed to meet 75% of the peak hour demand, providing a buffer for recovery time.
Details: Correctly sizing a hot water tank is essential for energy efficiency, cost savings, and ensuring adequate hot water supply. An undersized tank will run out of hot water quickly, while an oversized tank wastes energy and increases costs.
Tips: Enter your peak hour hot water demand in gallons per hour. This is typically calculated by summing the flow rates of all fixtures that might be used simultaneously during your busiest hour.
Q1: What is peak hour demand?
A: Peak hour demand is the maximum amount of hot water used during the busiest hour of the day, typically during morning routines when showers, sinks, and appliances are used simultaneously.
Q2: Why multiply by 0.75?
A: The 0.75 multiplier accounts for the tank's recovery rate, ensuring the heater can meet demand while maintaining a reserve for continuous usage.
Q3: How do I calculate my peak hour demand?
A: Add up the flow rates (in gallons per hour) of all hot water fixtures that might be used at the same time during your busiest hour.
Q4: Does this work for tankless water heaters?
A: No, this formula is specifically for storage tank water heaters. Tankless systems are sized based on flow rate and temperature rise requirements.
Q5: Should I round up the calculated size?
A: Yes, it's generally recommended to round up to the nearest available tank size to ensure adequate capacity.