Product · Multilayer · Size
16mm & 20mm PEX-AL-PEX Pipe — Wall Thickness, Coil Lengths & Oxygen-Tight Core
The two fastest-moving multilayer sizes from one German brand — 16 mm for underfloor heating loops, 20 mm for risers and distribution. Butt-welded aluminium core, oxygen-tight beyond DIN 4726, built to EN ISO 21003 and ASTM F1281/F1282.
Same five-layer build as the full range, focused on the two sizes that carry most of the work — in the coil lengths installers actually ask for.
Hitze supplies the trade — wholesalers, contractors and importers. We do not sell to end-consumers.
EN ISO 21003 · DIN 4726 The Two Sizes
See 16mm & 20mm PEX-AL-PEX Up Close
The 16 mm loop size and the 20 mm supply size, coil and straight, one German-engineered multilayer build. Studio shots of both diameters below.
16 & 20mm Specs
16mm & 20mm PEX-AL-PEX Pipe — Dimensions, Wall Thickness & Coil Lengths
Two sizes, fully specified — the numbers you need before you order a coil.
| Nominal OD | Wall Thickness | SDR (approx.) | Coil Lengths | Straight Lengths | Primary Use |
|---|---|---|---|---|---|
| 16 mm | 2.0 mm | ~8 | 100 m | 5 m | Underfloor heating loops |
| 20 mm | 2.0 mm | ~10 | 100 m | 5 m | Risers & distribution |
Wall thickness, SDR and length values above are industry-typical reference figures. Hitze production parameters are confirmed in the Technical Data Sheet — exact 16 / 20mm wall, SDR and coil/straight length options: coming soon.
OD / Wall-Thickness Tolerance (measured)
| Size | Parameter | Nominal | Tolerance |
|---|---|---|---|
| 16 mm | Outer diameter | 16.0 mm | Available on request |
| 16 mm | Wall thickness | 2.0 mm | Available on request |
| 20 mm | Outer diameter | 20.0 mm | Available on request |
| 20 mm | Wall thickness | 2.0 mm | Available on request |
| Both | Aluminium core | Butt-welded, full-length | Continuous |
Operating envelope: designed for continuous hydronic heating service and potable hot/cold water — pressure/temperature class per EN ISO 21003. Exact rated bar / ℃ class: available on request.
Download the 16 & 20mm Spec Sheet
Dimensional tables, tolerances, coil options and pressure/temperature ratings for both sizes in one PDF. Business email required.
Aluminium Core
The Oxygen-Tight Aluminium Core — Why It Matters at 16mm & 20mm
Both the 16 mm and 20 mm pipe share the same defining feature: a continuous, butt-welded aluminium core sandwiched between cross-linked polyethylene walls.
Because the aluminium is welded end-to-end rather than lapped, it forms a 100% oxygen barrier along the full length of every coil — 0% oxygen diffusion, exceeding DIN 4726. This is what turns a plastic pipe into a hydronic-grade heating pipe.
The same five-layer stack runs across both diameters — outer PEX / adhesive / bright aluminium / adhesive / inner PEX — so the tolerance stack, bend behaviour and joint fit stay consistent whether you’re laying a 16 mm loop or feeding it from a 20 mm supply.
Hydronic Protection
In a closed heating loop, oxygen ingress is what corrodes boilers, circulators and steel manifolds. A full-length welded aluminium core stops it — the failure mode plain non-barrier PEX invites. This is exactly why 16 mm is specified for underfloor loops.
Shape Retention
The aluminium core lets both sizes hold a hand-bent shape — faster installs, fewer clips, tighter turns on 16 mm loops.
Low Thermal Expansion
The core cuts linear expansion far below plain PEX, controlling sag and noise on hot 20 mm runs.
True Five-Layer Build
Outer PEX / adhesive / bright aluminium / adhesive / inner PEX — the same construction across both diameters, so the tolerance stack is consistent.
Both 16 mm and 20 mm are extruded on the same line to the same five-layer recipe, so a wholesaler stocking both carries a single, predictable tolerance stack rather than two unrelated products. Ask the team to confirm the aluminium core is butt-welded, not lapped, on the layer-by-layer TDS.
Size Selection
16mm for Underfloor Loops, 20mm for Risers & Distribution
The two sizes do different jobs — and stocking both from one source covers most of a whole-house heating and supply install.
| 16 mm | 20 mm | |
|---|---|---|
| Primary role | Underfloor / radiant floor heating loops | Risers, supply & distribution runs |
| Why this size | Bends tighter, longer coils, suits 100–150 mm pipe spacing | Higher flow to feed multiple loops / manifolds |
| Typical form | Long coils (100 m) | Shorter coils + straight lengths |
| Connects to | Underfloor manifold ports | Manifold trunk, distribution headers |
- 16 mm — the loop size. Long coils mean a room’s loop runs without a buried splice; the oxygen-tight core protects the whole hydronic circuit. This is the workhorse of radiant floor heating (US: “radiant floor / hydronic”; UK/EU: “underfloor heating”) — wet/hydronic systems, not electric.
- 20 mm — the supply size. Steps up flow for risers and to feed distribution manifolds where 16 mm loops branch off.
Bottom line for buyers: carry 16 mm and 20 mm together and you cover loop and supply from one multilayer line — fewer SKUs, one tolerance stack, one warranty conversation.
Talk to us about a 16 & 20mm program → Dedicated loop pipe →
Compliance & Supply
Certified to EN ISO 21003 — Buy Bulk or Private Label
Both sizes are manufactured to EN ISO 21003 (multilayer hot- and cold-water piping) and ASTM F1281/F1282 for PEX-AL-PEX, with the oxygen barrier meeting DIN 4726.
Hitze is certified to cUPC / NSF-61 / DVGW / WRAS & CE, so 16 mm and 20 mm are documented for both North American and European submittals. Specific certificate and listing numbers: available on request in the Cert Pack.
For Wholesalers & Distributors
Stock the two fastest-moving multilayer sizes from one source — 16 mm loops and 20 mm supply, coils and straight, heating and potable. Consistent tolerance, documented compliance, low MOQ on just these two SKUs. Ask for the current price list and MOQ — MOQ, lead time and FOB: coming soon.
Request a Quote →For Private-Label Brands & Importers
German-standard manufacturing under your brand — your logo on 16 mm and 20 mm pipe, on the coil lengths your market expects, EN ISO 21003 and NA/EU documentation behind them. Low MOQ to start on these two sizes, design confidentiality, full ODM path.
Start Private Label →Request the Cert Pack
EN ISO 21003, ASTM F1281/F1282 and the cUPC / NSF-61 / DVGW / WRAS & CE listings for both sizes, ready for your submittal and customs files. Certificate numbers available on request.
FAQ
16mm & 20mm PEX-AL-PEX Pipe — Buyer FAQ
What is the wall thickness of 16mm PEX-AL-PEX pipe?
What coil lengths do 16mm and 20mm come in?
Should I use 16mm or 20mm for underfloor heating?
Can I order just 16 and 20mm under my own brand?
Are 16 and 20mm compliant for both NA and EU submittals?
Get Started
Request the 16 & 20mm Spec Sheet & a Quote
Tell us your volumes, coil lengths and target market for 16 mm and 20 mm — we reply with pricing, MOQ, lead time and the certification documents for your region.