Basis: for 2″ and below, use velocity limit 4 ft/s. For above 2″, use head loss limit 4 ft per 100 ft.
This CHW Pipe Size Calculator helps HVAC engineers, MEP designers, and contractors quickly select a recommended chilled water pipe size based on chilled water flow rate. It is designed for fast preliminary sizing of chilled water supply and return piping in systems such as AHUs, FCUs, and chilled water distribution networks.
The calculator follows an ASHRAE-style sizing approach:
When you enter your chilled water flow rate, the tool calculates and displays:
The calculator selects the smallest acceptable pipe size that meets the applicable limit to support practical sizing and efficient pumping.
Enter your chilled water flow rate based on load calculations, coil schedules, or equipment submittals. Results update instantly.
The tool displays the recommended pipe size along with velocity and head loss so you can quickly validate the design against project constraints.
Excessive chilled water velocity can increase noise and accelerate wear in piping. That’s why smaller pipes are often governed by velocity limits.
For larger pipes, head loss strongly affects pump head and energy use. Controlling friction loss helps reduce pump power and improves system efficiency.
Many designers keep chilled water velocity around 2 to 6 ft/s depending on application and noise limits. This tool uses 4 ft/s for 2″ and below as a practical sizing limit.
A common design target for larger CHW piping is around 4 ft per 100 ft. This tool uses 4 ft/100 ft as the head loss limit for pipes above 2″.
Yes. The calculation uses Schedule 40 steel pipe internal diameters to estimate velocity and friction loss.
You can use it as a quick estimate, but final sizing may differ due to temperatures, viscosity, and project requirements. Always verify against your specifications and standards.
This calculator is best for preliminary sizing and quick verification. Final design should account for fittings, valves, strainers, coil pressure drop, balancing requirements, and actual system layout.