How To Calculate Water Heater Size

Introduction: Selecting the right size for a water heater is essential to ensure an adequate and efficient supply of hot water. This article introduces a calculator designed to help you determine the required water heater size in BTU/hour based on your desired water temperature, flow rate, and temperature rise.

Formula: The formula used in this calculator involves multiplying the flow rate, temperature rise, 8.33 (weight of a gallon of water), and a factor of 70 (representing 70% efficiency). The result is then divided by 1.2 to account for the specific heat of water.

How to Use:

  1. Enter the desired water temperature in Fahrenheit.
  2. Input the flow rate in gallons per minute.
  3. Specify the temperature rise required.
  4. Click the “Calculate” button to get the required water heater size in BTU/hour.

Example: If you need hot water at 120°F, have a flow rate of 3 gallons per minute, and require a temperature rise of 40°F, the calculation would be: (3 * 40 * 8.33 * 70) / 1.2 = 7000. Therefore, the required water heater size would be 7000 BTU/hour.

FAQs:

  1. Q: Why is calculating water heater size important? A: It ensures that the water heater can meet the hot water demand of a household or facility.
  2. Q: What factors influence the required water heater size? A: Desired water temperature, flow rate, and temperature rise are key factors.
  3. Q: What is the efficiency factor, and why is it used? A: The efficiency factor accounts for heat losses in the water heating process.
  4. Q: Can I use this calculator for different types of water heaters? A: Yes, the calculator provides a general guideline suitable for various types of water heaters, including tankless and storage tank models.
  5. Q: Is there a standard temperature rise for water heaters? A: The required temperature rise depends on the desired hot water temperature and the incoming water temperature.

Conclusion: Calculating the required water heater size is crucial for meeting hot water demands efficiently. Use this calculator to estimate the appropriate water heater size in BTU/hour based on your specific requirements, ensuring a reliable and sufficient supply of hot water for your needs.

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