Importance of PPRC Pipe Diameter Selection
When PPRC pipe diameter is selected incorrectly, two different problems arise: oversized diameter increases cost; undersized diameter drops pressure, leaving bathrooms and kitchens with insufficient flow.
Basic Concepts: PN Class
- PN10 (SDR 11): Withstands 10 bar at 20°C. Sufficient for standard building plumbing.
- PN16 (SDR 7.4): For high pressure lines and heating circuits. Standard residential choice.
- PN20 (SDR 6): Industrial applications requiring high temperatures.
Practical Diameter Selection Table
| Location | Connection Points | Recommended Diameter |
|---|---|---|
| Single apartment (basin, shower, WC, kitchen) | 4–6 points | Ø20 – Ø25 |
| Floor riser (4–6 apartments) | 20–30 points | Ø32 – Ø40 |
| Building main entry (10–20 apartments) | 50–80 points | Ø50 – Ø63 |
| Large building / complex entry | 80+ points | Ø75 – Ø90 |
| Boiler / heating connection | — | Ø20 – Ø25 |
4 Most Common Diameter Mistakes
- Undersizing the main riser: Installing Ø32 at building entry causes flow drops in all apartments during morning peak hours.
- Not calculating long runs: Runs over 20m create pressure loss; upsizing by one diameter may be needed.
- Using PN10 for hot water: Lines exposed to water above 70°C must use PN16 or PN20.
- Partial replacement: Using different diameters when adding PPRC to an old galvanised system disrupts flow balance.
Polyfusion Welding Times by Diameter
| Diameter (mm) | Heating Time (s) | Joining Time (s) | Cooling (min) |
|---|---|---|---|
| Ø20 | 5 | 4 | 2 |
| Ø25 | 7 | 4 | 2 |
| Ø32 | 8 | 6 | 4 |
| Ø40 | 12 | 6 | 4 |
| Ø50 | 18 | 6 | 4 |
| Ø63 | 24 | 8 | 6 |
| Ø75 | 30 | 8 | 8 |
| Ø90 | 40 | 8 | 8 |
These values are for 20°C ambient temperature. In cold weather (below 10°C), add 20–30% to heating times.