1. What is a Tankless Gas Water Heater Calculator?

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

Purpose: It helps homeowners and plumbers determine the appropriate size tankless water heater needed for a household.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The calculator sums the flow rates of all fixtures that might be used simultaneously to determine the peak demand.

3. Importance of Proper Sizing

Details: Correctly sizing a tankless water heater ensures adequate hot water supply during peak usage while avoiding unnecessary energy costs from an oversized unit.

4. Using the Calculator

Tips: Enter the flow rates for each fixture in your home. Default values are provided for typical fixtures. All values must be ≥ 0.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical GPM for a shower?
A: Standard showerheads use 2.5 GPM, while low-flow models may use 1.5-2.0 GPM.

Q2: How many fixtures can run simultaneously?
A: Most homes can run 2-3 fixtures at once. Add the GPM of all fixtures that might run together.

Q3: What size tankless heater do I need?
A: Residential units typically range from 7-10 GPM. Choose a unit that meets or exceeds your calculated total.

Q4: Should I include outdoor fixtures?
A: Yes, if you plan to use hot water outdoors (e.g., for washing cars or outdoor showers).

Q5: What about temperature rise?
A: This calculator determines flow rate only. Consider your climate and incoming water temperature when selecting a unit.