1. What is Indirect Water Heater Sizing?

Indirect water heater sizing calculates the appropriate tank size needed based on the heating coil output, desired recovery time, and temperature difference. Proper sizing ensures efficient hot water delivery while minimizing energy consumption.

2. How Does the Calculator Work?

The calculator uses the indirect water heater sizing formula:

Where:

• \( \text{coil\_output} \) — Heating coil output capacity in BTU per hour
• \( \text{time} \) — Desired recovery time in hours
• \( \Delta T \) — Temperature difference between incoming cold water and desired hot water temperature in °F

Explanation: The formula calculates the required tank size by determining how much water can be heated to the desired temperature within the specified time period using the available heating capacity.

3. Importance of Proper Sizing

Details: Proper water heater sizing is crucial for energy efficiency, adequate hot water supply, and system longevity. Oversized units waste energy, while undersized units cannot meet hot water demands.

4. Using the Calculator

Tips: Enter coil output in BTU/h, recovery time in hours, and temperature difference in °F. All values must be positive numbers. Typical ΔT values range from 70-100°F depending on your climate and desired water temperature.

5. Frequently Asked Questions (FAQ)

Q1: What is a typical coil output for residential systems?
A: Residential systems typically range from 30,000 to 150,000 BTU/h depending on the boiler size and system design.

Q2: How long should the recovery time be?
A: Typical recovery times range from 0.5 to 2 hours for most residential applications. Shorter times require larger heating capacity.

Q3: What ΔT value should I use?
A: Standard calculation uses 70°F ΔT (from 50°F incoming to 120°F output). Adjust based on your local water temperature and desired output temperature.

Q4: Can this calculator be used for commercial systems?
A: Yes, but commercial systems may require additional factors such as peak demand calculations and multiple tank configurations.

Q5: What if I have multiple hot water fixtures?
A: For systems with multiple simultaneous fixtures, you may need to increase the tank size or consider a larger heating capacity to maintain adequate supply.