Per metre, we tell the truth.
The Ridgeline figures use the same corrugated-tube friction model as our heat pump checker, with the real internal diameter for each size. We did not smooth the corrugation away to flatter our own product.
Free tool for UK installers and specifiers
What does your pipe run really lose?
Set the run and flow: the tool auto-sizes the Ridgeline line and compares velocity and pressure loss against copper and PEX at the water temperature you actually run. Straight from the Ridgeline engineering toolbox.
Auto-sizing built in
7 Ridgeline sizes
Copper + PEX side by side
Temperature-corrected
316L stainless
WRAS approved
KIWA Reg 4
Compare your run.
Live results as you move the sliders. The Ridgeline size auto-selects to the smallest size that passes the 2.0 m/s design rule and your pressure allowance (override it any time); elbow losses count against copper and PEX, and Ridgeline routes the whole run as one continuous formed length.
Open the calculator.
Tell us who you are and the tool opens straight after.
We use your name, email and company to give you access to the calculator and to reply if you raise a Ridgeline project question. We rely on legitimate interest for that follow-up; you can object at any time. We don’t share your details outside Ridgeline Tubes Limited. See our privacy policy.
Sizing heat pump primaries? Use the dedicated checker: 16 named UK heat pumps, pump headroom budgets and a pass or step-up verdict for the primary run.
Heat pump sizing checker →How to read the result
Three numbers, one honest story.
Per metre, corrugated stainless steel carries more friction than smooth copper, and this tool shows it. Whole systems are a different question: every soldered elbow and insert fitting adds a velocity-head loss, and Ridgeline replaces them with continuous formed bends. Compare totals, not just the per-metre column.
Systems are not straight lines.
The elbow column is where rigid systems give ground. Each copper elbow and each PEX insert fitting costs a slice of pressure, and PEX fittings neck the bore down further. Count the elbows your route actually needs and read the totals.
Match the duty, not the label.
Pipe sizes are not like-for-like by the number on the label. R-22 is engineered to run like 20 mm PEX; R-32 HP runs like 28 mm copper. The tool auto-matches the fair comparison for each size, and you can override it.
If the numbers work, here is what you also get
The install case for Ridgeline.
Cut, slide, tighten.
No soldering. No flame. No hot-works permit. Same connection technique indoors and outdoors. Continuous bends in place of soldered elbows reduce the joint count on long runs.
One system end to end.
Same Ridgeline tube from the cylinder or manifold to the furthest outlet. Fewer transitions on suitable end-to-end runs. One supplier route for the whole-home pipework.
100+ year design life.
316L marine-grade stainless steel. WRAS approved, KIWA Reg 4 certified. Avoids copper- and plastic-specific failure modes (pinholing, stress cracking). Engineering-convention design life for 316L stainless in water service. 25-year commercial warranty is the separate narrower commitment.
Fewer joints behind walls.
Bend the tube around obstacles in long continuous runs. Most joints come out from behind the wall to accessible locations. Lower long-term escape-of-water risk.
Need help sizing a specific job?
Send us your drawings.
For whole-property sizing, plant rooms, long routes or anything close to your pressure budget, our technical team will size the system, return a tube schedule and flag anything that needs a design review. Free for live projects.
Request a design review →See it before you spec it
Hold a length of Ridgeline.
A free sample tells you more about Ridgeline than any data sheet. Bend it. Look at the corrugation. See how it routes around an obstacle. We’ll post one to your work address.
Request a sample →
Comparison tool for first-pass design support. Results are indicative and depend on the entered run length, flow rate, temperature and fitting count. Final system design, pipe sizing and compliance with BS EN 806 / BS 8558 and Water Regulations remain the responsibility of the installer or designer.
Method: Darcy-Weisbach pipe friction with iterated Colebrook-White friction factor (laminar f = 64/Re below Re 2300). Roughness ε: Ridgeline corrugated 316L 0.845 mm (the same calibrated value as our heat pump checker; never smoothed away), copper 0.0015 mm, PEX 0.007 mm. Internal diameters per the Ridgeline engineering toolbox; 35 mm copper modelled at 32.6 mm bore per BS EN 1057 R250 with 1.2 mm wall. Water viscosity and density are corrected to the selected temperature (20 to 60°C) and applied to all three materials equally.
Elbow losses: Δp = Kρv²/2 with K = 1.0 per elbow, applied to copper and PEX. PEX elbows are modelled at the velocity through the fitting bore, taken as the tube bore minus 3 mm (typical insert-fitting reduction). Ridgeline runs are modelled as one continuous formed length with no added elbow losses; where a Ridgeline run does require fittings, add their manufacturer-published losses to the Ridgeline total. Tees, valves and other components are outside the scope of this comparison.
Auto-sizing: picks the smallest Ridgeline size from R-22 upward that passes two checks: flow velocity within the 2.0 m/s design limit BS EN 806-3 applies to header, rising and floor service pipes, and whole-run loss within your entered pressure allowance (default 500 mbar, a screening figure you should replace with your system's real budget when known). R-15 is excluded from auto-sizing (the toolbox reserves it for short end runs and drop-ins); every size remains selectable manually. Auto-sizing is a first-pass screening aid, not a system design.
Flow presets are typical UK design figures with diversity applied, rounded for screening (BS EN 806-3 loading-unit conventions and common UK fixture flow rates). Confirm demand against the actual fixture set, and measure the incoming supply where the mains feed is being sized.