How to Use
Select a calculation mode and hydraulic method. Enter actual tube dimensions and system pressure. Add every important fitting before calculating.
Review velocity, pressure loss, and remaining outlet pressure. Compare nearby sizes before choosing tubing. Confirm the result with manufacturer information.
Hydronic mode estimates loop flow from heat demand. Fixture mode provides preliminary demand only. Final designs require professional verification.
Example Data
| Scenario | Tube | Length | Flow | Inlet pressure | Purpose |
|---|---|---|---|---|---|
| Residential branch | 1/2 in nominal | 60 ft | 3 GPM | 55 psi | Check branch velocity and residual pressure. |
| Whole-house trunk | 3/4 in nominal | 100 ft | 8 GPM | 60 psi | Compare standard tube sizes. |
| Radiant loop | 1/2 in nominal | 250 ft | 1 GPM | 12 psi | Estimate circulator head requirements. |
Frequently Asked Questions
Which pressure-loss method should I use?
Hazen–Williams is convenient for water systems. Darcy–Weisbach uses fluid viscosity and Reynolds number. Compare methods when uncertainty matters.
Why is actual inside diameter important?
Flow area depends on inside diameter. Small diameter changes strongly affect velocity and friction. Use verified tubing dimensions whenever possible.
How are fittings included?
Each fitting can use a K-value or L/D ratio. Quantities are multiplied automatically. Custom fittings can be added anytime.
What does pressure loss per 100 feet show?
It normalises straight and fitting friction across pipe length. This supports easier system comparisons. Elevation pressure is reported separately.
What is remaining outlet pressure?
It is inlet pressure minus friction and elevation effects. Higher elevation reduces outlet pressure. Downhill flow can increase available pressure.
Can the calculator size parallel pipes?
Yes, total flow divides among identical parallel pipes. The calculation assumes equal resistance. Real systems may require balancing valves.
How is hydronic flow estimated?
Hydronic flow uses heating load and temperature difference. Glycol concentration applies a capacity correction. Pump selection needs complete system data.
Is fixture demand exact?
No, fixture mode is a preliminary estimate. Local demand rules may differ. Confirm final sizing using applicable requirements.
Why does the calculator show Reynolds number?
Reynolds number identifies the likely flow regime. It also supports Darcy friction calculations. Transitional results deserve careful review.
Can glycol properties be entered manually?
Yes, density and viscosity remain editable. Use fluid data at operating temperature. Glycol mixtures may increase pressure losses significantly.
Does this replace professional design?
No, the calculator supports preliminary engineering analysis. Ratings and installation rules still apply. Qualified review is recommended for critical systems.
Engineering Notice
Results depend on entered dimensions, fluid properties, fittings, and design limits. Verify tubing ratings, joining systems, local requirements, and manufacturer data before installation.