Electric Tankless Water Heater GPM Calculator

Electric Tankless Water Heater Formula:

\[ Q = \frac{kW \times 3.412}{\Delta T \times 8.34} \]

Flow Rate (Q):

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1. What is the Electric Tankless Water Heater GPM Formula?

The electric tankless water heater GPM formula calculates the flow rate in gallons per minute that an electric tankless water heater can produce based on its power rating and the desired temperature rise.

2. How Does the Calculator Work?

The calculator uses the electric tankless water heater formula:

\[ Q = \frac{kW \times 3.412}{\Delta T \times 8.34} \]

Where:

\( Q \) — Flow rate (gallons per minute)
\( kW \) — Power input (kilowatts)
\( \Delta T \) — Temperature rise (°F)
3.412 — Conversion factor (BTU per watt-hour)
8.34 — Weight of one gallon of water (pounds)

Explanation: The formula converts electrical power to thermal energy and calculates how much water can be heated per minute based on the temperature difference required.

3. Importance of GPM Calculation

Details: Accurate GPM calculation is crucial for sizing electric tankless water heaters properly, ensuring adequate hot water supply for household needs, and optimizing energy efficiency.

4. Using the Calculator

Tips: Enter the water heater's power rating in kilowatts and the desired temperature rise in °F. Both values must be positive numbers for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is temperature rise (ΔT)?
A: Temperature rise is the difference between the desired output water temperature and the incoming cold water temperature.

Q2: How do I determine the required temperature rise?
A: Measure your incoming cold water temperature and subtract it from your desired hot water temperature (typically 120°F).

Q3: What is a typical GPM requirement for households?
A: Typical requirements range from 2-5 GPM depending on the number of bathrooms and simultaneous hot water uses.

Q4: Why is this calculation important for tankless water heaters?
A: Unlike tank water heaters, tankless units heat water on-demand, so the GPM rating determines how much hot water can be delivered simultaneously.

Q5: Can this formula be used for gas tankless water heaters?
A: No, gas units use a different calculation based on BTU input rather than electrical power.