Proper sizing is essential for getting the best performance from your tankless water heater system. Understanding these basic guidelines will help you select the right unit for your specific application.
Understanding Flow Rate Capacity
The flow rate capacity of tankless water heaters depends on the temperature difference between the desired output and the incoming water temperature. This relationship is fundamental to determining which unit will meet your hot water needs.
Key Sizing Factors
Takagi water heaters are sized according to three critical factors:
- Peak flow rate requirements - The maximum hot water demand for your application
- Extreme temperature-rise scenarios - The greatest temperature increase your system will need to provide
- Types of applications - Whether residential, commercial, or specialized use
Once these factors have been determined, refer to either the flow rate comparison charts or the flow rate chart found in each model's specifications. Select the appropriate water heater as well as the amount of water heaters required.
Professional Sizing Approaches
Application designers and engineers can decide whether to size for full flow, expected flow, or utilize probability models such as the modified "Hunter Curve".
Hunter Curve Method for Large Applications
For large scale applications such as hotels, apartment complexes, and large restaurants, Hunter Curves are commonly used to estimate the peak flow rate demand when given the total amount of fixture units within an application. It is up to the application designer/engineer to determine the amount of fixture units within any given application.
Visual Sizing Tools
The flow rate comparison chart and table shown below summarize the flow rate charts found in the specifications of each model, making it easier to compare options and make informed decisions.
Basic Sizing Guidelines Chart
Flow Rate Guide Chart
Hunter Curve Chart
Making Your Selection
After reviewing these charts and determining your specific requirements, you can select the appropriate water heater as well as determine the number of water heaters required for your application. The combination of understanding your peak flow rate requirements, temperature-rise scenarios, and application type will guide you to the optimal solution.