1. What is a Tankless Water Heater Sizing Calculator?

Definition: This calculator determines the appropriate size for a gas tankless water heater based on your total hot water demand.

Purpose: It helps homeowners and plumbers select a properly sized tankless water heater to meet simultaneous hot water needs.

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 fixture (GPM)

Explanation: The flow rates of all potential simultaneously used fixtures are summed to determine the total demand, then rounded up to the nearest 11 GPM unit.

3. Importance of Proper Sizing

Details: Correct sizing ensures adequate hot water supply while maximizing energy efficiency and preventing undersized units that can't meet demand.

4. Using the Calculator

Tips: Enter the flow rates for each fixture in your home. Default values are provided for typical fixtures. The calculator will recommend an appropriately sized 11 GPM unit.

5. Frequently Asked Questions (FAQ)

Q1: Why 11 GPM units?
A: 11 GPM tankless heaters are commercial-grade units suitable for large homes with high simultaneous demand.

Q2: What if my total is less than 11 GPM?
A: The calculator will still recommend an 11 GPM unit as the minimum for this category, providing capacity for future needs.

Q3: How accurate are the default flow rates?
A: Defaults represent average values; for precise calculations, measure your actual fixture flow rates.

Q4: Should I consider temperature rise?
A: This calculator assumes standard temperature settings. For extreme climates, consult a professional for additional capacity.

Q5: Can I run multiple 11 GPM units in parallel?
A: Yes, for very large homes, multiple units can be installed in parallel to meet higher demands.