1. What is an Electric Tankless Water Heater GPM Calculator?

Definition: This calculator estimates the total gallons per minute (GPM) flow rate required for an electric tankless water heater based on fixture flow rates.

Purpose: It helps homeowners and plumbers determine the appropriate size for an electric tankless water heater by calculating the simultaneous hot water demand.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total required flow rate (GPM)
• \( Q_i \) — Flow rate of each individual fixture (GPM)

Explanation: The calculator sums the flow rates of all fixtures that might be used simultaneously to determine the total GPM requirement.

3. Importance of GPM Calculation

Details: Proper GPM estimation ensures your tankless water heater can provide enough hot water during peak demand periods without temperature fluctuations.

4. Using the Calculator

Tips: Enter the GPM for each fixture in your home. Default values are provided for common fixtures. The calculator sums all values to determine total GPM requirement.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical GPM range for tankless water heaters?
A: Most electric tankless water heaters provide 3-5 GPM, depending on the model and incoming water temperature.

Q2: Should I include all fixtures in my home?
A: Only include fixtures that might be used simultaneously. For example, two showers running at the same time.

Q3: What if my actual usage exceeds the calculated GPM?
A: The water temperature will drop. Consider a higher capacity unit or staggering hot water use.

Q4: How do I find my fixtures' GPM?
A: Check manufacturer specifications or look for the WaterSense label (2.0 GPM max for showers, 1.5 GPM for faucets).

Q5: Does this account for temperature rise?
A: No, this calculates flow rate only. Temperature rise depends on your climate and groundwater temperature.