1. What is a Tankless Water Heater Size Calculator?

Definition: This calculator estimates the required flow rate (in gallons per minute) for a tankless water heater based on your fixture usage.

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

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

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

Explanation: The flow rates of all potential simultaneously used fixtures are summed to determine the total demand.

3. Importance of Proper Sizing

Details: Correct sizing ensures adequate hot water supply without oversizing the unit, which improves energy efficiency and reduces costs.

4. Using the Calculator

Tips: Enter the flow rates for all fixtures that might be used simultaneously. Default values represent typical residential fixture flow rates.

5. Frequently Asked Questions (FAQ)

Q1: What's a typical GPM requirement for a home?
A: Most homes need 5-10 GPM, depending on the number of bathrooms and appliances.

Q2: Should I consider future additions?
A: Yes, if planning to add fixtures, include them in your calculation now.

Q3: What about temperature rise?
A: This calculator determines flow rate only. Temperature requirements affect the BTU rating needed.

Q4: How do I find my fixture flow rates?
A: Check manufacturer specs or use a bucket to measure gallons per minute.

Q5: Should I add a safety factor?
A: It's recommended to add 10-20% to the calculated GPM for peak demand periods.