The Manthorpe GRS-DUO seals and guides 10mm flexible plastic barrier pipework at radiator wall penetrations. A twin-plate system that handles first and second fix in one, preventing air leakage and kinking while leaving a clean finish.
The Manthorpe GRS-DUO Radiator Pipe Guide and Seal is one of those small details that makes a real difference on a modern heating install. Designed specifically for 10mm flexible plastic barrier pipework, it solves two problems at once: sealing the wall penetration against air leakage, and guiding the pipework cleanly from the wall to the valve points without kinking or chafing. If you’ve ever watched a pipe slowly work its way through a ragged plasterboard hole with nothing holding it straight, you’ll appreciate what this product does.
The system works across two stages of the build. At first fix, the rear mount plate is fixed to the wall, anchoring the pipework at exactly the right exit point. This keeps things aligned before the plasterboard goes on, which matters more than it might sound. The mount plate is compatible with both blockwork and stud wall construction, and the multiple pilot hole locations mean you’ve got flexibility on plasterboard thickness and radiator offset.
How the Manthorpe GRS-DUO Handles the Second Fix
Once the plasterboard is up and the room is being finished, the cover plate goes on. A single central fixing screw secures it, and crucially, it can fix back into the mount plate itself rather than into the plasterboard around the cut edge. Anyone who’s tried to get a decent fixing near a plasterboard cutout will know that’s a welcome detail. The cover plate sits flush against the wall, sealing the penetration and producing a clean, professional finish behind the radiator.
The flexible grommets seal around the pipework while still allowing for slight directional adjustment, which is handy when the pipe run doesn’t come through at a perfect angle. The guide channels curve the pipe naturally towards the valve positions at the outer corners, taking the stress out of the bend and keeping the pipe from being forced into a tight radius that could cause problems later.
For anyone fitting radiators with 10mm plastic barrier pipe, the GRS-DUO is a neat solution to a fiddly detail that often gets bodged with a blob of filler and a chrome rose that doesn’t quite cover the hole.
Pro Tip: Fix the mount plate to the structure at first fix before boarding, not to the plasterboard itself, so the cover plate screw has something solid to bite into at second fix regardless of where the board edge falls.
The GRS-DUO is used on new build and renovation heating installations where 10mm flexible plastic barrier pipe is run to radiators through a plasterboard or blockwork wall. It suits the kind of detail common in modern timber frame and stud wall construction, though it works equally well on traditional blockwork backgrounds. Plumbers and heating engineers fitting radiators at second fix will find it particularly useful on projects where airtightness is a consideration, such as properties built to Part L or Passivhaus-influenced specifications.
Best For
Sealing radiator pipe penetrations in plasterboard or blockwork walls
First and second fix heating installations
10mm flexible plastic barrier pipework
Airtight construction details
New build and renovation projects
Compatible With
10mm flexible plastic barrier pipe
Stud wall and timber frame construction
Blockwork wall construction
Standard plasterboard thicknesses
Various radiator and wall offset configurations
Key Features
Twin plate design for first and second fix stages
Single screw fixing to mount plate, no plasterboard fixings needed
Flexible grommets with directional adjustability
Guide channels prevent pipe kinking
Multiple pilot hole locations for installation flexibility
Patent pending design
Not suitable for: Not suitable for 15mm or 22mm copper or plastic pipework. This product is designed specifically for 10mm flexible plastic barrier pipe and will not seal correctly around larger diameter pipes.
Fix the rear mount plate to the wall structure at first fix, positioning the pipework through the guide channels at the correct exit point. Secure with appropriate fixings for the wall type. The multiple pilot hole locations allow the plate to be positioned to suit the plasterboard thickness and radiator offset you are working with.
Once boarding and plastering are complete, feed the 10mm pipe through the cover plate grommets and fix the cover plate back to the mount plate using the single central screw. No fixings into the plasterboard are required. Check the pipe curves naturally through the guide channels towards the valve positions before tightening off.
Mark the pipe exit point on the wall at first fix, accounting for the radiator position and valve locations
Fix the rear mount plate to the wall structure using fixings appropriate for blockwork or stud, selecting the pilot hole positions that suit your offset
Feed the 10mm plastic barrier pipe through the mount plate guide channels at the correct angle
Complete the boarding and any plastering or skimming works
Cut the plasterboard opening over the mount plate and feed the pipe through
Thread the pipe through the flexible grommets in the cover plate
Align the cover plate over the mount plate and fix with the single central screw, checking the pipe curves cleanly towards the valve points before fully tightening
Can the GRS-DUO be used on a solid blockwork wall rather than a stud partition?
Yes. The mount plate is designed to work with both stud wall and blockwork construction. You will need to use appropriate fixings for the substrate, but the plate itself accommodates both wall types without modification.
Does the cover plate have to fix into the plasterboard, or can it fix directly to the mount plate?
The cover plate fixes directly back into the mount plate using a single central screw. You do not need any fixings into the plasterboard around the cut edge, which is particularly useful where the opening is close to a board edge and there is little material left to fix into.
The GRS-DUO is a two-component thermoplastic system comprising a rear mount plate and a front cover plate with flexible grommets. The mount plate provides structural anchorage at first fix, with multiple pilot hole positions to accommodate different wall builds and offsets. The cover plate grommets form a flexible air seal around 10mm plastic barrier pipe, and the design carries patent pending status.
Product Code
GRS-DUO
Pipe Diameter
10mm
Pipe Type
Flexible plastic barrier pipe
Fixing Method
Single central screw to mount plate
Wall Compatibility
Blockwork, stud wall, timber frame
Install Stage
First fix and second fix
Patent Status
Patent pending
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