1. What is an Electric Tankless Water Heater Calculator?

Definition: This calculator determines the required size of an electric tankless water heater based on your household's peak hot water demand.

Purpose: It helps homeowners and plumbers properly size tankless water heaters to ensure adequate hot water supply.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total flow rate (gallons per minute)
• \( Q_i \) — Flow rate of each individual fixture

Explanation: The calculator sums the flow rates of all potentially simultaneous hot water fixtures to determine peak demand.

3. Importance of Proper Sizing

Details: Undersized heaters can't meet demand, while oversized units waste energy. Proper sizing ensures consistent hot water and energy efficiency.

4. Using the Calculator

Tips: Enter the number of each type of fixture in your home. The calculator uses standard flow rates (2.5 GPM for showers, 1.5 GPM for sinks, etc.).

5. Frequently Asked Questions (FAQ)

Q1: Why is 9 GPM recommended for large households?
A: 9 GPM can typically handle 2 showers (5 GPM) plus other fixtures running simultaneously.

Q2: What if my fixtures have different flow rates?
A: Adjust the values in the calculator to match your specific fixtures' flow rates.

Q3: Does this account for temperature rise?
A: No, this calculates flow rate only. Temperature rise depends on incoming water temperature and desired output.

Q4: How many electrical circuits are needed?
A: A 9 GPM unit typically requires multiple 240V circuits (often 3-4 x 40-50A circuits).

Q5: Can I use this for gas tankless heaters?
A: The flow rate calculation is similar, but gas models have different sizing considerations.