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Pegasus Pressfit Larger Bore Fittings — 28mm, 35mm, 42mm and 54mm M-Profile for UK Plumbers
When pipe sizes go beyond 22mm, soldering copper stops being quick and starts being a liability. Heat soaking through large-bore fittings, confined plant rooms, insurance restrictions on open flames near insulation — all of it pushes contractors toward press-fit. Pegasus M-Profile pressfit fittings cover 28mm, 35mm, 42mm and 54mm in the same tool-press system used for 15mm and 22mm, so your RIDGID or Rothenberger press tool handles the whole job from first-fix header to final boiler flow connection.
This guide covers the larger-bore Pegasus Pressfit M-Profile range stocked at APM Electricals: what each size is used for, where the M-Profile system fits in the press-fit market, and how to spec the right fitting first time.
Why Press-Fit for Larger Bore?
Soldering a 42mm or 54mm joint requires significant heat, a long heat-soak time, and a very clean, dry pipe. On large commercial heating installations or plant room builds, that means hot-works permits, fire-watch periods, and the constant risk of a failed joint behind a ceiling or inside a plant room casing. Press-fit eliminates all of that.
A Pegasus M-Profile press takes seconds per joint. The fitting is pre-loaded with an EPDM O-ring; once pressed, the joint is watertight and rated for central heating (closed-circuit water up to 110°C) and cold water supply (up to 70°C, PN16). No flux, no naked flame, no dry-pipe wait. For larger bore work, the time savings compound quickly — a 42mm ring-main around a plant room might have 40+ joints, each one a potential hot-works incident with traditional solder.
The Pegasus M-Profile System
M-Profile (also called TH-profile) is the most widely used press-fit profile in the UK and Europe. It is compatible with all major press tools from RIDGID, Rothenberger, Milwaukee, and Virax using the correctly sized M-Profile jaws. The profile creates a mechanical crimp that locks the fitting onto the pipe and compresses the O-ring to form a seal in a single press cycle.
Pegasus M-Profile fittings are manufactured to work with copper pipe to BS EN 1057. They are not compatible with plastic or stainless-steel-specific profiles. For commercial copper pipework from 28mm upward, Pegasus M-Profile is a proven, WRAS-accepted solution.
28mm Pegasus Pressfit — Boiler Connections and Sub-Mains
28mm is the most common larger-bore size in domestic and light commercial heating. Boiler flow-and-return connections are typically 28mm on any output above around 18kW. Sub-main runs feeding multiple bathroom zones, underfloor manifolds, and mid-size commercial radiator circuits all use 28mm as their primary bore.
The Pegasus 28mm range covers couplers, elbows, tees, street elbows, reducing couplers (28mm x 15mm, 28mm x 22mm), slip couplers for in-situ repair, stopends, and obtuse elbows. This gives you the same comprehensive fitting selection at 28mm that you would expect in 15mm or 22mm copper.
Common applications:
- Boiler primary flow/return connections (combi, system, and heat-only boilers above 18kW)
- Unvented cylinder primary coil connections
- Plant room sub-main distribution to zone valves
- Commercial domestic hot water (DHW) circulation mains
- Buffer vessel connections
35mm Pegasus Pressfit — Commercial Heating Mains
35mm sits between domestic-heavy 28mm and full commercial 42mm. It is used on commercial heating primaries where 28mm is undersized for the flow rate but 42mm would be oversized and expensive. School heating systems, small office block plant rooms, and multi-flat heat interface unit (HIU) primaries often run 35mm copper on their main distribution loops.
Pegasus 35mm M-Profile fittings include couplers, elbows, street elbows, obtuse elbows, tees, reducing couplers (35mm x 15mm, 35mm x 22mm, 35mm x 28mm), slip couplers, and stopends. Having the full range available off-the-shelf at APM Electricals means specifying 35mm is practical rather than a procurement headache.
Common applications:
- Commercial heating primary mains (10–50kW plant room output)
- HIU primary flow/return in apartment block heat networks
- Plant room pipework bridges between 28mm zone circuits and 42mm boiler headers
- Large unvented DHW cylinder coil connections
42mm Pegasus Pressfit — Plant Room Headers and Large Commercial
42mm is the standard bore for large commercial heating headers, condensate neutraliser outlets, and primary mains on plant rooms with boiler output upward of 50kW. Large heat pump installations, gas-fired commercial boiler banks, and district heating shared plant commonly use 42mm copper for their main flow-and-return circuits.
Pressing a 42mm joint with a good-quality press tool is still a single-person, seconds-per-joint operation. Compare that to the time and risk of a 42mm solder joint in a confined plant room with existing insulation and you can see why 42mm press-fit has become the default on most commercial M&E projects.
Pegasus 42mm M-Profile fittings include couplers, tees, street elbows, obtuse elbows, reducing couplers (42mm x 28mm, 42mm x 35mm), slip couplers, and stopends. The 42mm tee at £20.15 is competitive against alternative press-fit brands and significantly cheaper than a brazed or soldered alternative when you factor in labour and hot-works costs.
Common applications:
- Commercial boiler plant room primary headers
- Large air-source and ground-source heat pump primary circuits
- District heating building entry points (where copper is specified over pre-insulated MLCP)
- Industrial process cooling water mains
- Large-scale underfloor heating manifold feeds
54mm Pegasus Pressfit — District Heating and Large Plant
54mm is the largest common copper pipe size in UK commercial building services. It is used on main distribution risers in multi-storey buildings, large boiler plant room primary loops, and district heating connections at the point of entry into a building. Traditional 54mm soldering (or brazing) is a skilled operation that takes significant time per joint. 54mm press-fit brings that down to seconds, with no flame and no hot-works permit.
Pegasus 54mm M-Profile fittings include couplers, street elbows, reducing couplers (54mm x 42mm), stopends, and tees. For typical large plant room pipework, the coupler and street elbow cover the majority of joints, with the tee used at branch take-offs.
Common applications:
- Large commercial boiler plant primary loop (100kW+ combined output)
- District heating building entry and primary distribution riser
- Hospital and leisure centre main heating distribution
- Large data centre or industrial cooling water mains
M-Profile Tool Compatibility
To use Pegasus M-Profile fittings at 28mm–54mm you need a press tool with jaws sized for M-Profile and for each bore you are pressing. Most professional tools (RIDGID RP 340, Rothenberger Romax Compact TT, Milwaukee M18 FORCE LOGIC) support interchangeable jaw sets covering 15mm through 54mm M-Profile. Buy the jaw set for the bore sizes on your job — the tool body is the same investment you already use for 15mm and 22mm.
Always follow the fitting manufacturer's guidance on pipe insertion depth, pipe squareness, and the absence of burrs or external contamination at the press point. A correctly prepared press-fit joint is as reliable as a solder joint; a poorly prepared one can leak. Check the O-ring is seated before pressing — the "unpressed fitting" indicator (a gap visible on an unpressed fitting) should be gone after the press cycle.
Stocking Larger-Bore Pressfit
For plant room work and commercial heating, carrying a range of 28mm–54mm Pegasus M-Profile fittings on the van reduces return trips and avoids project hold-ups waiting for next-day deliveries. APM Electricals stocks the full Pegasus M-Profile range across 15mm to 54mm with same-day dispatch on orders placed before 3pm.
Summary
Pegasus M-Profile press-fit fittings at 28mm, 35mm, 42mm, and 54mm extend the speed and no-flame advantages of press-fit into every copper pipe size used in UK commercial heating and plumbing. With 50+ active Pegasus Pressfit SKUs in stock at APM Electricals — couplers, elbows, tees, reducers, slip couplers, and stopends across the full bore range — you can specify press-fit from first-fix through to large plant room headers and order everything from one supplier.
APM Electricals | Specialist Trade Supplier | apmi.uk
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