1. What is a Tankless Water Heater Calculator?

Definition: This calculator estimates the total flow rate (GPM) needed for sizing a tankless water heater based on fixture flow rates.

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

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 (GPM)

Explanation: The flow rates of all potential simultaneously used fixtures are summed to determine the required capacity of the tankless water heater.

3. Importance of Proper Sizing

Details: Correct sizing ensures adequate hot water supply during peak demand while avoiding oversized units that waste energy.

4. Using the Calculator

Tips: Enter the flow rate for each fixture in GPM. Default values are provided for typical residential fixtures.

5. Frequently Asked Questions (FAQ)

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

Q2: How do I find my fixture flow rates?
A: Check manufacturer specifications or measure with a bucket and stopwatch (gallons collected ÷ seconds × 60).

Q3: Should I consider simultaneous use?
A: Yes, sum the flow rates of all fixtures that might be used simultaneously during peak demand.

Q4: What about temperature rise requirements?
A: This calculator determines flow rate only. Consider a separate calculation for temperature rise based on your climate.

Q5: Should I add a safety margin?
A: It's recommended to add 10-20% to the calculated flow rate for unexpected demand.