1. What is the GPM Calculator for Tankless Water Heater?

The GPM (Gallons Per Minute) calculator for tankless water heaters determines the flow rate based on the heater's BTU rating and the desired temperature rise. This helps in selecting the right size tankless water heater for your needs.

2. How Does the Calculator Work?

The calculator uses the GPM formula:

Where:

• \( Q \) — Flow rate in gallons per minute (GPM)
• \( BTU \) — British thermal units per hour
• \( \Delta T \) — Temperature rise in °F

Explanation: The formula calculates how many gallons of water can be heated per minute based on the heater's energy output and the required temperature increase.

3. Importance of GPM Calculation

Details: Proper GPM calculation ensures your tankless water heater can meet your hot water demands. Undersized units may not provide enough hot water, while oversized units waste energy and money.

4. Using the Calculator

Tips: Enter the BTU rating of your tankless water heater and the desired temperature rise. Typical temperature rise is 40-70°F depending on your climate and incoming water temperature.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical GPM requirement for a household?
A: Most households need 2-5 GPM depending on the number of bathrooms and simultaneous hot water uses.

Q2: How do I determine the required temperature rise?
A: Subtract your incoming groundwater temperature from your desired hot water temperature (typically 120°F).

Q3: What BTU rating do I need for my home?
A: Residential tankless water heaters typically range from 140,000 to 199,000 BTU. Larger homes with higher demand need higher BTU ratings.

Q4: Can I run multiple fixtures simultaneously?
A: Yes, but the total GPM demand of all running fixtures must not exceed your tankless water heater's capacity.

Q5: How does altitude affect tankless water heater performance?
A: At higher altitudes, BTU ratings may need to be derated. Consult manufacturer specifications for altitude adjustments.