Hydronic Pipe Capacity: PEX
Hydronic system pipe capacity data — maximum recommended flow rate (GPM), velocity, friction loss, and inside diameter for closed-loop HVAC hydronic systems by pipe material and nominal size
| pipe material | nominal size in | friction loss ft per 100ft (ft/100ft) | inside diameter in (in) | max recommended gpm (gpm) | notes | pipe roughness ft (ft) | velocity at max gpm fps (fps) |
|---|---|---|---|---|---|---|---|
| PEX | 0.5 | 12 | 0.475 | 1.5 | PEX-A CTS dimensions ASTM F876; max temp 180F; max 5 fps residential hydronic | 0.000007 | 5.4 |
| PEX | 0.75 | 12.5 | 0.671 | 3 | 3/4-in PEX; standard radiant and fan-coil branch | 0.000007 | 8.5 |
| PEX | 1 | 12 | 0.857 | 5 | 1-in PEX; manifold supply trunk | 0.000007 | 8.7 |
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