1. What is a Tankless Water Heater GPM Calculator?

Definition: This calculator estimates the required flow rate (GPM) for a tankless water heater based on simultaneous fixture usage.

Purpose: It helps homeowners and plumbers properly size tankless water heaters to meet 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 simultaneous fixture (GPM)

Explanation: The calculator sums the flow rates of all fixtures that might run simultaneously to determine the minimum required GPM capacity.

3. Importance of Proper GPM Calculation

Details: Correct GPM sizing ensures your tankless water heater can meet peak demand without temperature fluctuations or insufficient flow.

4. Using the Calculator

Tips: Enter the GPM for each fixture that might run simultaneously. Default values are provided for common fixtures.

5. Frequently Asked Questions (FAQ)

Q1: What if I have more fixtures than listed?
A: Add additional fixture GPM values to the calculation. Most tankless systems can handle 2-3 simultaneous fixtures.

Q2: What's a typical shower GPM?
A: Standard showerheads use 2.5 GPM, while low-flow models use 1.5-2.0 GPM.

Q3: How do I find my fixture's GPM?
A: Check manufacturer specs or look for the GPM rating on the fixture.

Q4: Should I include all fixtures in my home?
A: Only include fixtures that might run simultaneously during peak usage.

Q5: What about temperature rise considerations?
A: This calculator determines flow requirements. Temperature rise depends on groundwater temperature and heater capacity.