1. What is a Tankless Water Heater Sizing Calculator?

Definition: This calculator determines the required flow rate (in gallons per minute) for a tankless water heater based on your fixtures' flow rate and a safety factor.

Purpose: It helps homeowners and plumbers select the properly sized tankless water heater for their needs.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( GPM \) — Required flow rate (gallons per minute)
• \( Fixtures\ Flow \) — Combined flow rate of all fixtures (gal/min)
• \( Factor \) — Safety factor (typically 1.5)

Explanation: The fixtures' total flow rate is multiplied by a safety factor to ensure adequate hot water supply during peak usage.

3. Importance of Proper Sizing

Details: Correct sizing ensures sufficient hot water supply, energy efficiency, and prevents overworking the unit.

4. Using the Calculator

Tips: Enter the combined flow rate of all fixtures (gal/min) and the safety factor (default 1.5). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: How do I determine my fixtures' flow rate?
A: Add up the flow rates (usually marked on fixtures) of all hot water devices you might use simultaneously.

Q2: Why is the factor typically 1.5?
A: This accounts for simultaneous use and ensures adequate capacity during peak demand.

Q3: What's a typical GPM requirement?
A: Most homes need 5-10 GPM, but this varies based on the number of bathrooms and appliances.

Q4: Should I consider temperature rise?
A: Yes, this calculator determines flow rate only. You'll also need to consider the required temperature increase.

Q5: What if I have high-flow fixtures?
A: Consider low-flow alternatives or select a unit with higher capacity to accommodate them.