1. What is a Tankless Water Heater Capacity Calculator?

Definition: This calculator determines the required capacity (in gallons per minute) for a tankless water heater based on the flow rates of all connected fixtures.

Purpose: It helps homeowners and plumbers properly size a tankless water heater to meet simultaneous hot water demands.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( Q \) — Total required capacity (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 minimum required capacity.

3. Importance of Proper Sizing

Details: Correct capacity calculation ensures adequate hot water supply, prevents temperature fluctuations, and optimizes energy efficiency.

4. Using the Calculator

Tips: Enter the flow rate (GPM) for each fixture that might be used simultaneously. Typical flow rates: shower (2.5 GPM), sink (1.5 GPM), dishwasher (1.5 GPM).

5. Frequently Asked Questions (FAQ)

Q1: What if I have more than 3 fixtures?
A: Add their flow rates to one of the existing inputs or consult a professional for complex systems.

Q2: How do I find my fixture's flow rate?
A: Check manufacturer specifications or measure by timing how long it takes to fill a 1-gallon container.

Q3: Should I include cold water fixtures?
A: No, only include fixtures that will use hot water from the tankless heater.

Q4: What about temperature rise considerations?
A: This calculator determines flow capacity only. Temperature requirements affect model selection, not basic capacity.

Q5: Should I add a safety margin?
A: Yes, consider adding 10-20% to the calculated capacity for optimal performance.