Male BSP
R-32 HP tube to 1″ Male BSP thread.
Code: P1-SM-32-10
Air source heat pump pipework
Pipework, ready for the heat pump.
Corrugated 316L stainless steel for air source heat pump flow and return. Long flexible runs, fewer fittings, and Ridgeline R-32 HP for the ASHP-class hydraulic range.
UK-designed. WRAS approved. KIWA Regulation 4 certified. Designed to make the awkward routing parts of an ASHP install simpler.
316L marine-grade stainless
WRAS approved
KIWA Reg 4
15 bar / 150 °C
UK designed
The brief
Heat-pump pipework is not boiler pipework.
Like-for-like boiler-to-ASHP swaps fail when the pipework is treated as a commodity SKU choice. Four reasons heat-pump pipework deserves its own specification.
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Flow-rate sensitive
Heat pumps are not boilers. Undersized or over-restricted pipework starves the heat pump of flow. Pipe selection has to start from the manufacturer's hydraulic schedule.
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Long external runs
The outdoor unit is rarely next to the plant room. Flexible 316L stainless tube routes around obstacles and through awkward building fabric in continuous lengths.
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Insulation-critical
Flow and return run hot. Whatever the pipe, insulation has to handle outdoor exposure, vapour barrier integrity and the temperature regime the heat pump operates at.
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Retrofit-awkward
Most installs go into existing homes. Routing has to thread through joists, voids and external skin without rebuilding the building.
Where it fits
Three zones in an ASHP install.
Ridgeline earns its place in the routes that copper and rigid pipe handle worst.
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Zone 01
Outdoor unit to plant room
Primary flow and return pipework from the heat pump enclosure into the plant room. Sized for hydraulic class, insulated for external exposure, routed in long continuous runs to minimise hidden joints.
Specification note: check size against flow and pressure-drop requirements. R-32 HP is positioned for the typical 28mm-class hydraulic range of domestic ASHP installs.
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Zone 02
Plant room and cylinder area
Connections, manifolds, distribution runs into heating circuits and the buffer or hot-water cylinder. The zone where commissioning, isolation and maintenance access matter most.
Specification note: keep service valves, drain points and primary connections accessible. P1 mechanical fittings handle the high-temperature pressure regime.
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Zone 03
External and concealed routes
Pipework that runs outside the building, through external skins, or through long concealed routes inside walls and floors. The hardest zone to get right with rigid pipe.
Specification note: insulate to system design and outdoor exposure, with vapour barrier integrity. Ridgeline's flexible routing avoids fittings in the hardest-to-access places.
R-32 HP
Purpose-built for ASHP primary pipework.
Most domestic heat-pump designs assume a hydraulic class similar to 28 mm copper. R-32 HP is positioned for that gap — a corrugated 316L stainless tube size sized for primary flow and return rather than smaller domestic distribution.
- Designed for
- ASHP primary flow and return
- Hydraulic class
- 28 mm-class (domestic ASHP range)
- Material
- Corrugated 316L stainless steel
- Working pressure
- 15 bar (with P1 fittings)
- Operating temp
- Up to 150 °C (with P1 fittings)
- Approvals
- WRAS · KIWA Reg 4
R-32 HP fittings
Four P1 fittings, sized for R-32 HP.
Drop R-32 HP tube into 1″ BSP threads or 28 mm copper compression without adapters. Same patented metal-on-metal seal as every other P1 fitting in the range.
Female BSP
R-32 HP tube to 1″ Female BSP thread.
Code: P1-SF-32-10
Copper Elbow
90° elbow, R-32 HP tube to 28 mm copper compression.
Code: P1-ECC-32-28
Copper Straight Union
R-32 HP tube to 28 mm copper compression union.
Code: P1-CC-32-28
Full SKU list and ordering codes in the P1 data sheet. Other P1 fittings (BSP, copper, tees, unions) shown on the products page.
On the project
Specifier checklist.
Six things to confirm before pipework goes on the spec sheet. Treat each as a deliverable — written, signed, included in the project pack.
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Confirm system parameters
Heat-pump output, required flow rate and route length signed off by the heating designer.
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Size from data, not assumption
Select tube size using Ridgeline technical data and the heat-pump manufacturer's hydraulic schedule.
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Specify insulation per zone
External, unheated and concealed runs all need explicit insulation specification — material, thickness, vapour barrier.
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Keep critical fittings accessible
Service valves, drain points and primary connections should remain reachable for commissioning and future maintenance.
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Build the proof pack
Data sheets, approval certificates and installation instructions all included before issue for construction.
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Use technical support
Ask Ridgeline technical support to review unusual routes, long external runs or uncertain sizing before pipework is ordered.
Steps 1–3 sit with the heating designer. Steps 4–6 sit with the project specifier and installer.
Suggested specification wording
Drop into your spec.
Ridgeline corrugated 316L stainless steel plumbing tube for air source heat pump flow and return applications, installed with Ridgeline-approved fittings in accordance with manufacturer data sheets, installation instructions, approval documents and project design requirements.
Edit project-specific tube size, fitting system and insulation references into this wording before issuing for construction.
Insulation
Ridgeline solves routing. Insulation still solves heat loss.
Both must be specified. Pipe choice does not replace insulation specification.
- External flow and return must be insulated according to system design, manufacturer guidance and local climate exposure.
- Vapour barriers matter. Failed vapour barriers cause condensation, fitting corrosion and long-term insulation collapse.
- External wall and skin penetrations should be sealed and protected against UV, mechanical damage and rodent attack.
- Long continuous runs reduce fittings — but support spacing, clipping and thermal-movement allowance still apply.
Move from research to product proof.
Hold a length of corrugated 316L stainless steel tube. Read the Heat Pump Specifier Guide. Or talk to the team about a specific project.