Free tool for UK heat pump installers

Will Ridgeline fit your next heat pump job?

Select the heat pump, route length and fittings. The calculator checks whether Ridgeline R-32 HP stays inside the available pipework headroom, or whether R-35 / design review is the safer call.

Run the check →

12 heat-pump options 6 pipe sizes Manufacturer-published data 316L stainless WRAS approved KIWA Reg 4

The tool

Run the check.

Choose the pump, route and fittings. The chart updates instantly.

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.

Heat-pump output 9 kW

Drag to slide the YOU ARE HERE line across the chart.

Run length 18 m

Enter combined flow + return tube length. If the outdoor unit is 12 m from the cylinder, start at 24 m then add offsets and vertical drops.

Directional-change fittings 8

Elbows + bends that change pipe direction on the primary run (flow + return total). A typical UK ASHP route sits around 6–10. Count the actual route where possible. Ridgeline replaces these with continuous bends, which is where it saves. (Isolators, diverter, filter and manifold are already in the System Architecture loss below, so don’t double-count them here.)

Reference pump

★ Auto-matched to your kW

System architecture 300 mbar

Non-pipework losses to subtract from the pump's published headroom: cylinder coil, diverter, magnetic filter, UFH manifold and fittings. Mitsubishi EHPT pumps already include these internally, so the selector applies only an external 50 mbar in that case. Per CIBSE Guide C + Heat Geek + MCS designer convention.

Primary ΔT 5 K

Temperature drop across the heat pump flow ↔ return. NOT the radiator/UFH ΔT. This is the heat-pump-side number that sets primary flow rate.

Fluid

Water temperature

Copper fitting K 0.9

Generic minor-loss factor for a standard 90° copper elbow per CIBSE Guide C / Crane TP-410. Replace with manufacturer-specific fitting data where available.

MLCP fitting K 2.0

Generic allowance for press-fitting / reduced-bore losses. Replace with manufacturer-specific fitting data where available.

Pressure drop vs heat-pump output

Pump budget: 250 mbar

Each curve = total pressure drop (friction + fittings) for that pipe size. Where the curve crosses the red cap line = the kW above which you’d need to step up.

R-32 HP / R-35 28 / 35 mm copper 32 / 40 mm MLCP Step-up (dashed) Pump cap Your kW

Coloured dots on the cap line mark where each material hits the budget on this scenario. The visual order tells you which would need stepping up first. For the “how much room do I have” read, see the cards below.

At 9 kW: current pressure drop and how much room you have to grow

Screening check only: this calculator checks design heating flow and pipework friction. Always verify manufacturer minimum / maximum / defrost flow, DHW reheat requirements, pump settings and the final MCS design separately. Final responsibility for sizing rests with the installer or accredited heating designer.

R-32 HP

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Headroom on this scenario

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28 mm copper

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Headroom on this scenario

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32 mm MLCP

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Headroom on this scenario

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If Ridgeline fits, here is what you also get

The install case for Ridgeline on ASHP.

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 heat-pump connection through the wall to the manifold and cylinder. Fewer transitions on suitable end-to-end runs. One supplier route for the primary 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 closed-loop heating water service; see methodology for basis. 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.

How to read the result

What this check is actually telling you.

Does the selected Ridgeline size stay inside your pump’s available pipework headroom for the inputs shown? Pass is a screening green-light. Near-cap or fail means step up, simplify the route, enter verified pump data, or request a design review. The tool models R-32 HP’s corrugation friction against smooth copper without smoothing the cost away.

One chart, one answer.

Drag the kW slider. The vertical line moves through every curve, showing each pipe’s current pressure drop. When a curve rises above the pump cap, that pipe needs to step up. Pass or fail is visual.

The Ridgeline curve is the real one.

R-32 HP corrugation has more straight-run friction than smooth copper. The tool models that honestly, calibrated against Ridgeline + P1 published pressure-loss data. We did not flatten the curve to flatter our own product.

If it fits, the site benefits are yours.

Fewer joints. Easier routing around obstacles. No hot-works permit. Continuous bends in place of soldered elbows. The pressure check earns the right to the install advantages.

Need help sizing a specific job?

Send us your drawings.

For boiler-to-heat-pump conversions, new-build plant rooms, longer routes or anything close to the circulator’s head budget, our technical team will size the system, return a tube schedule and BOM, 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 →

Screening tool for first-pass design support. Results are indicative and depend on the selected pump, design flow, ΔT, route length, system allowance and fitting assumptions. Final system sizing, pump selection, manufacturer flow checks and MCS compliance remain the responsibility of the installer or accredited heating designer.

Method: Darcy-Weisbach pipe friction with Colebrook-White friction factor and configurable minor-loss allowances for discrete directional fittings. Ridgeline R-32 HP and R-35 friction is calibrated against the Ridgeline + P1 Data Sheet. Copper and MLCP fitting losses are generic and should be adjusted where manufacturer-specific fitting data is available. Glycol mixtures use ASHRAE Fundamentals Ch. 31 specific-heat-capacity values and the calculated flow rate is density-corrected.

Pump head figures are taken or derived from manufacturer documentation and should be verified against the exact model, pump setting, glycol concentration and installation architecture used on the project. The tool checks design heating flow only; verify manufacturer minimum flow, maximum flow, defrost volume, DHW reheat requirements and commissioning requirements separately.

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Hydraulics: Darcy-Weisbach + Colebrook-White + excess-velocity-head minor losses (Crane TP-410 / Idelchik / CIBSE Guide C §4). Roughness ε: copper 0.0015 mm, MLCP 0.007 mm, R-32 HP / R-35 ε=0.845 mm calibrated to Ridgeline + P1 pressure-loss data at representative heat-pump primary flow rates (water, 10–40 L/min, 40 °C). Friction factor for corrugated stainless tube cross-referenced against Vicente, García & Viedma 2004 (IJHMT 47, 671–681) and ASME IMECE 2014 PLT tests; calc sits within the published peer-reviewed band.

Pump headroom sources. Vaillant aroTHERM Plus tabulated "Remaining feed pressure, hydraulic": manual 0020330791_03 p.46 (VWL 35/55/75), 0020330792_03 p.49 (VWL 105/125). Daikin Altherma 3 M EBLA09-16 "Pump → Nominal Heating ESP": EEDEN20 data book at EN 14511 A7/W35 ΔT5. Daikin EBLA08: EEDEN22A p.52 ESP curve at 21.5 L/min (no published nominal). Mitsubishi WM85 / WM112: derived from the current EHPT EW installation manual (Doc 716856 / Jan 2025 / FTC7 / UPM4L pump) Graphs 1+3 + PUZ-WM databook outdoor-unit pressure-difference values. Space Heating cylinder curve used throughout (not DHW). Graph reads cross-checked against the Grundfos UPM4L OEM data sheet (independent source with kPa axis on the same pump curves). The older EHPT DW1 / FTC6 / UPM3L range manual remains relevant to installed systems and stock still encountered in the field; the UPM3L pump curve runs ~5–7 kPa lower than UPM4L at WM112 design flow, so DW1 installs should treat the displayed pipework budget as ~10% optimistic. NIBE F2120: circulator-dependent; default uses Grundfos UPM3 25-75 head minus 1 kPa NIBE HX.

Mitsubishi flow-basis caveat. WM85 and WM112 budgets are derived at each unit's nominal heating flow (24.4 L/min and 32.1 L/min respectively), which sits at the upper bound of the permitted flow range. Installs running below rated flow will see proportionally more pump head available than the calculator shows; the upper-bound figure is used as a conservative design-point screening assumption. Pipework friction in the calculator is recomputed at the user's actual kW + ΔT, so lower-kW scenarios get lower friction even though the pump budget is held constant.

System-loss allowances. Editable screening assumptions representing common UK system architectures (compact pre-plumbed / typical separate cylinder / complex with buffer). Designers should replace them with project-specific component pressure drops where available. Defaults were set against published CIBSE / BSRIA / Heat Geek and MCS-aligned design references. Indicative component breakdown for the three presets:

Preset	Typical components	Allowance
Compact pre-plumbed	Cylinder coil ~70–100 mbar + magnetic filter ~20–30 mbar + local fittings ~30–50 mbar	150 mbar
Typical UK	Cylinder coil ~80–120 mbar + UFH manifold ~50–80 mbar + magnetic filter ~20–30 mbar + diverter valve ~30–50 mbar + local fittings ~30–50 mbar	300 mbar
Typical UK + blending valve	Typical UK preset above + TMV ~50 mbar	350 mbar
Complex	Cylinder coil ~80–120 mbar + buffer tank ~100–150 mbar + 2-3 zone valves ~60–90 mbar + TMV ~50 mbar + manifold ~80 mbar + filter + local fittings ~60 mbar	550 mbar

Component figures are screening estimates only. Real values vary by cylinder model, manifold size, filter selection and valve geometry. Mitsubishi EHPT is a special case: the pre-plumbed cylinder unit (as listed in the EHPT installation manual’s Component / Parts Identification section) pre-deducts pump + plate HX + diverter + filter + LLH, so the calculator applies only ~50 mbar for external valves there.

Glycol: SHC values 4.18 / 3.93 / 3.69 kJ/kg·K for water / 25% / 44% PG at 40 °C per ASHRAE Fundamentals Ch. 31 / Energy Saving Trust Green Heat Toolkit. Flow rate density-corrected per fluid.

Note on Lancaster University 2022 study: the Lancaster work tested corrosion (XPS / ICP-OES / optical microscopy), not hydraulics. It supports corrosion-resistance claims, not pressure-loss claims.

Material durability basis (100+ year design life claim). The design life figure rests on the engineering convention for 316L marine-grade stainless steel in closed-loop heating water service (low oxygen, conditioned chemistry, benign corrosion environment). The Lancaster University 2022 corrosion study tested Ridgeline tube samples for corrosion behaviour and supports the corrosion-resistance basis. Design life is the engineering-convention assessment of material life under expected service conditions; the 25-year commercial warranty is the separate, narrower commitment.

Pump-data evidence pack. Every pump-headroom value in this calculator with the manufacturer document, page/section it came from, the raw published value, what physical boundary it represents, and our confidence in the figure. Where a public source URL is available, the document title links to the source PDF; for derived or shared-pump rows, the source column references the relevant document instead.

Reading the table. “Raw pump / source head” is the manufacturer or derived head available at the cylinder outlet, before the system-architecture allowance is subtracted. The live chart shows a lower “Pump budget” figure: raw head minus the selected system-architecture loss (150 / 300 / 350 / 550 mbar). For Mitsubishi EHPT options, only 50 mbar is deducted because the cylinder unit internals are treated as pre-deducted.

Pump option	Raw pump / source head	Source document & revision	Page / section	Raw published value	Boundary	Confidence
Vaillant aroTHERM 75	440 mbar	Vaillant install manual 0020330791_03 (06.11.2023)	p.46 Technical Data, Heating circuit	44.0 kPa “Remaining feed pressure, hydraulic” at max flow 1,205 L/h	External head at outdoor unit (gross of cylinder + valves)	High. Published tabulated.
Vaillant aroTHERM 105	550 mbar	Vaillant install manual 0020330792_03	p.49 Technical Data, Heating circuit	55.0 kPa “Remaining feed pressure, hydraulic”	External head at outdoor unit	High
Vaillant aroTHERM 125	550 mbar	Same as VWL 105 (shared pump)	p.49	55.0 kPa	External head at outdoor unit	High
Daikin Altherma 3 M EBLA08	580 mbar	Daikin Data Book EEDEN22A (06/2022). Public mirror. Daikin’s official PDF is gated behind their professional portal; cite EEDEN22A in their Stand-By-Me library for reviewers with access.	p.52 §15-1 Static Pressure Drop Unit (ESP curve)	~58 kPa ESP read from curve at 21.5 L/min design flow (8 kW @ ΔT5). EEDEN22A does NOT publish a tabulated nominal ESP for EBLA04-08.	External head at outdoor unit	Medium-High. Primary curve read.
Daikin EBLA09	1065 mbar	Daikin Data Book EEDEN20 (10/2020). Public mirror. Daikin’s official PDF is gated behind their professional portal; cite EEDEN20 in their Stand-By-Me library for reviewers with access.	“Pump → Nominal Heating ESP” specification row	106.5 kPa published nominal ESP at EN 14511 A7/W35 ΔT5, pump at max PWM speed	External head at outdoor unit	Medium. Published tabulated; confirm exact model variant + pump-limit setting.
Daikin EBLA11	1030 mbar	EEDEN20 (same as EBLA09)	“Pump → Nominal Heating ESP”	102.9 kPa	External head at outdoor unit	Medium
Daikin EBLA14	965 mbar	EEDEN20	“Pump → Nominal Heating ESP”	96.5 kPa	External head at outdoor unit	Medium
Daikin EBLA16	714 mbar	EEDEN20	“Pump → Nominal Heating ESP”	71.4 kPa	External head at outdoor unit	Medium
Mitsubishi Ecodan WM85 + EHPT	290 mbar	EHPT EW install manual Doc 716856 (Jan 2025, UPM4L), primary derivation source. The older EHPT DW1 install manual Doc 607431 (Jan 2022, UPM3L, public mirror) remains relevant to installed systems and stock still encountered in the field; UPM3L pump curve runs slightly tighter than UPM4L, so DW1 installs should treat the displayed pipework budget as ~10% optimistic. Note: Mitsubishi’s library page URL/title for the EW PDF may still include DW1 / 7797271-02 metadata, but the downloaded PDF content is Doc 716856 EW / FTC7 / UPM4L.	Graph 1 (UPM4L pump curve, MAX PWM speed) p.14 + Graph 3 (small-cylinder Space Heating curve) p.17 + PUZ-WM85VAA databook §1.2 (outdoor-unit pressure difference)	Derived at 24.4 L/min (WM85 nominal heating flow, upper bound of permitted 10.8–24.4 L/min range): UPM4L head ~71 kPa − small-cylinder Space Heating ΔP ~24.5 kPa − PUZ-WM85 outdoor HX ΔP 15 kPa ≈ 31.5 kPa central / ~29 kPa conservative ≈ 290 mbar (conservative-end rounded value used).	Net of pre-plumbed cylinder unit internals (pump, plate HX, diverter, filter, LLH all pre-deducted per Component / Parts Identification)	Medium-High. Graph-read estimates cross-checked against the public copy of Grundfos UPM4L 25-75 OEM data sheet (independent source with kPa axis on the same pump curves) and an internal small-vs-large cylinder ratio consistency check. Conservative-end rounding from internal graph-read review dated 2026-05-26.
Mitsubishi Ecodan WM112 + EHPT	220 mbar	Same dual citation as WM85 row above (EW primary; DW1 ~10% more conservative)	Graph 1 (UPM4L pump curve, MAX PWM speed) p.14 + Graph 3 (large-cylinder Space Heating curve) p.17 + PUZ-WM112VAA databook §1.2	Derived at 32.1 L/min (WM112 nominal heating flow, upper bound of permitted 14.4–32.1 L/min range): UPM4L head ~69 kPa − large-cylinder Space Heating ΔP ~21 kPa − PUZ-WM112 outdoor HX ΔP 24 kPa ≈ 24 kPa central / ~22 kPa conservative ≈ 220 mbar (conservative-end rounded value used). Mitsubishi’s manual notes: “it may be necessary to add an additional pump to the system depending on the length and lift of the primary circuit”.	Net of pre-plumbed cylinder unit internals	Medium-High. Graph-read estimates cross-checked against the public copy of Grundfos UPM4L 25-75 OEM data sheet + internal small-vs-large cylinder ratio consistency check. Conservative-end rounding from internal graph-read review dated 2026-05-26.
NIBE F2120-8 + UPM3	750 mbar	NIBE F2120 installer manual IHB EN 2214-1 + Grundfos UPM3 Data Booklet p.9	F2120 manual p.44 spec table; UPM3 25-75 max-speed pump curve	75 kPa UPM3 25-75 head at design flow − 1 kPa NIBE plate-HX ΔP	External head at outdoor unit. Circulator-dependent (F2120 has no built-in pump).	Low-Medium. Depends on installer-chosen circulator; verify against actual installed pump.
NIBE F2120-12 + UPM3	730 mbar	Same as F2120-8	Same	73 kPa UPM3 head at 17.2 L/min − 1 kPa NIBE HX	External head at outdoor unit	Low-Medium
Generic UPM3 25-75	730 mbar	Grundfos UPM3 Data Booklet	p.9 Performance range graph	~73 kPa head at residential design flow, max PWM	External head. Screening estimate, not a specific OEM citation.	Low. Replace with manufacturer-specific pump curve.
Custom pump head	User input	Project-specific pump curve	Designer-supplied	User-entered value, treated as already-net pipework allowance (no system-loss subtracted)	User-defined	User responsibility

Pipe properties. R-32 HP: 27 mm ID, ε=0.845 mm calibrated to Ridgeline + P1 pressure-loss data at 10–40 L/min water at 40 °C. R-35: 33 mm ID, same ε. 28 mm copper: 26.2 mm ID, ε=0.0015 mm per CIBSE Guide C, K-elbow 0.9 per Crane TP-410. 32 mm MLCP: 26 mm ID, ε=0.007 mm, K-fitting 2.0 (generic press-fitting / reduced-bore allowance).

Fluid properties. Water and propylene-glycol viscosity / density per IAPWS-IF97 and DOW Propylene Glycol Engineering Guide. Specific heat capacity 4.18 / 3.93 / 3.69 kJ/kg·K for water / 25% / 44% PG at 40 °C per ASHRAE Fundamentals Ch. 31.

System-loss allowances. 150 / 300 / 550 mbar presets for Compact pre-plumbed / Typical UK / Complex with buffer, set against published CIBSE Guide C, BSRIA AG 20/95 and MCS-aligned design references. Mitsubishi EHPT special case: 50 mbar (external valves only) because cylinder unit pre-deducts internals.