Water Heater Brochure

Match the Unit to Your Needs
Condensing Units
Commercial Units
910
140H
Cooler Climates
50°F Incoming Groundwater Temperature
Warmer Climates
70°F Incoming Groundwater Temperature
Capacity - Number of Shower Heads (Assuming the set point temperature is 120˚F )
CT-199
110U
Non-Condensing Units
310U/C
510U/C
540H/P/X3
340H
240H
7 Showers
5 Showers
1.5 Showers
4.5 Showers
3 Showers
2.5 Showers
2.5 Showers
1.5 Showers
3.5 Showers
2.5 Showers
3.5 Showers
2.5 Showers
3.5 Showers
2.5 Showers
4 Showers
2.5 Showers
3 Showers
4.5 Showers
BASIC SIZING GUIDELINES
The flow rate capacity of tankless water heaters depends on the temperature difference between the desired
output and incoming water temperature. The flow rate comparison chart and table shown here summarize the
flow rate charts found in the specifications of each model.
A. O. Smith water heaters are sized according to the peak flow rate requirements, worst-case temperature-rise
scenarios, and types of applications. Once these factors have been determined, refer to either the flow rate
comparison here or the flow rate charts found in each model’s specifications. Select the appropriate water heater
as well as the amount of water heaters required.
Application designers/engineers can decide whether to size for full flow, expected flow, or utilize probability
models such as the modified “Hunter Curve.” 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.
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