How to choose the right installation tools for Hepworth piping

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Why choosing the right mounting accessories is not "just a detail"

When installing a Hepworth heating system, most attention is directed towards the pipes, fittings and boiler. Mounting accessories – clamps, brackets, pipe clamps, screws – seem at first glance to be insignificant details, bought according to what is currently available. This is a very common and costly mistake. From practice, I know that up to a third of complaints and service calls related to heating systems are connected precisely with poor pipe fixation or unsuitable connecting materials – not with the quality of the pipe itself.

The Hepworth pipe (more precisely PB – polybutylene pipe) has specific physical properties: significant thermal expansion, relatively softer surface compared to copper, and at the same time excellent flexibility. These properties dictate which mounting accessories are suitable and which are not. An incorrectly chosen clamp can cut the pipe or squeeze it to the extent that local stress occurs in the material. An unsuitable pipe clamp can cause a leak during the first load cycle of the system. And a bracket that is two millimeters too narrow will cause the pipe to shift from its position during thermal expansion, deforming the entire line.

This article will guide you through the entire selection process – from dimensions through types of accessories to specific products and real-life installation scenarios.

Basic typology of mounting accessories for Hepworth pipe

Before we move on to specific choices, it is useful to clarify into which categories the mounting accessories for Hepworth pipe are divided. Each category serves a different purpose and their combination forms a functional whole.

1. Mounting brackets and clamps

These are elements that physically fix the pipe to the base – wall, ceiling, floor or support profile. Brackets are long profile elements into which the pipe is inserted and clipped. Clamps are individual fixing elements that embrace the pipe and attach it to the base with one or two screws. A detailed comparison of clamps and brackets is covered in a separate article in the Knowledge Center: Clamps vs. brackets for pipe mounting – when to use which.

2. Pipe clamps and transition adapters

These elements solve the transition between different materials or diameters – typically the connection of PB pipe with copper pipe, or the connection to valve blocks, manifolds, or valves. These are hydraulically critical components: they must seal, withstand pressure and temperature, and at the same time must not damage the surface of the pipe.

3. Anchoring and connecting screws

Screws, wall plugs and anchors are an underestimated category. The type of screw (e.g. Kombi M8) and its length determine whether the mounting will be secure or whether it will loosen after a year.

Dimensions of Hepworth pipe and their influence on the choice of accessories

The first and most important thing you need to know before purchasing is the exact outer diameter of your pipe. Hepworth pipe is commonly supplied in diameters of 15 mm, 18 mm, 22 mm, 28 mm, 35 mm and larger. For domestic heating systems, the most common diameters are 15 mm and 18 mm, or their combination.

The catch is that with PB pipe, we always refer to the outer diameter – unlike some other systems, where the inner diameter or nominal bore is stated. If you are unsure, measure the pipe with a caliper at several points along its length – PB pipes have tolerances, but with a correct pipe, the measured values should not differ by more than 0.2 mm.

The choice of bracket or clamp size must exactly match the outer diameter. An oversized (larger) bracket will allow the pipe to vibrate and move; an overly tight (smaller) one will deform it. For typical family homes, it is therefore necessary to choose:

For 15 mm pipe: Pipe mounting bracket, 16 mm – this bracket is designed to compensate for standard PB pipe tolerances of Ø15 mm and at the same time allows thermal expansion without excessive squeezing.
For 16–18 mm pipe: Pipe mounting bracket, 16–18 mm – the variable profile of this bracket covers the entire range, which is practical especially for installations where diameters are combined or where precise technical documentation for the pipe is not available.

A detailed guide to diameter ranges and how to measure them correctly can be found in the article What size clamp or bracket do I need for my pipe in the Knowledge Center.

Mounting strips for pipe – when and how to use them

A strip is a profiled mounting aid that allows inserting a pipe into a groove and clipping it directly onto the pipe without screws. Its advantage is the speed of installation, surface-friendly handling of the pipe, and the possibility of installing a larger number of parallel pipes into one strip system next to each other.

Strips are ideal in situations where:

several pipe routes run in parallel (e.g., in a technical room or at a distribution point)
quick installation is needed for a large volume of work
the pipe runs under plaster, in a groove, or in a gypsum board structure – where it is not suitable to anchor each clip separately
future disassembly or inspection of the piping is expected

From a material perspective, strips are usually made of rigid plastic or steel profiles with a plastic insert. For PB pipe, it is important that the contact surface is smooth and free of sharp edges – any irregularity in the internal profile can scratch the surface of the pipe during temperature changes and weaken the wall over the long term.

Regarding spacing: for horizontal routes, I recommend installing a strip/clip every 500 to 700 mm for a diameter of 15–18 mm. For vertical routes, the spacing can be 800–1000 mm. These values are based on the need to prevent sagging of the pipe under its own weight, which is more relevant for PB material due to its flexibility than for copper or steel. The practical side of installation, including spacing, is described in the article How to correctly install clips and strips for pipes.

Transition fittings – a critical item when connecting to another material

A transition fitting is a connecting element that allows connecting a PB pipe to another system – most commonly to a copper pipe, a brass valve, or a brass thread of a plumbing block. It is not just about adapting the diameter – it is about a hydraulically tight and mechanically strong connection that must withstand repeated pressure and thermal cycles throughout the system's lifetime (20–50 years with proper installation).

To choose the correct transition fitting, you must know:

Outer diameter of the PB pipe (e.g., 15 mm)
Wall thickness of the pipe (e.g., 1 mm for Hepworth 15×1)
Type and dimension of the opposite thread or diameter (e.g., G½" external thread, or copper pipe Ø15)
Material of the opposite pipe – different fittings apply for copper piping, others for PB-PB connections

For connecting to a copper pipe of diameter 15 mm, the Transition fitting - for copper pipe - 15x1-EK is intended. The designation "EK" in this context means Eurocon – a standardized conical shape of the sealing surface, which ensures reliable sealing without the need for sealing tape or gasket. This fitting is specifically designed for a pipe wall thickness of 1 mm, which corresponds to the standard product Hepworth 15×1.

If you need to connect a PB pipe of diameter 15 mm either to another PB pipe or to a copper pipe, the Transition fitting 15 x 1 EK for copper or PB pipe comes into consideration. This solution is more universal and is appreciated by plumbers who do not always have precisely documented what type of pipe is on the other side of the connection.

Practical notes on the installation of transition fittings

In practice, I repeatedly encounter the situation where a transition fitting becomes loose or starts to leak within the first year of operation, not because the product is of poor quality, but because the installation was carried out without following a few basic rules:

The end of the pipe must be cut at a right angle. Any angle in the cut will cause uneven load on the conical surface and the connection will not seal properly. Use a pipe cutter, not a saw.
The pipe must be inserted all the way to the stop. Half insertion is the most common cause of leakage during the first pressure test.
The nut is tightened by hand and then an additional ¾ turn with a wrench. Over-tightening the nut deforms the conical surface and causes the exact opposite – leakage due to deformation.
Do not use Teflon tape on EK connections. Eurocon seals metal to metal (or plastic to metal). Adding tape disrupts the conical geometry.

More on this topic, including a step-by-step procedure, can be found in the article Transition fitting for copper pipe – selection and installation.

Screws and anchoring – an underestimated foundation of the entire piping system's stability

Each clip or strip is only as strong as its anchoring into the base. Screws and anchors must match not only the hole diameter in the clip but also the type of base (concrete, brick, gypsum board, wood, steel profile) and the expected load.

KOMBI M8 screw is a universal self-tapping anchor screw with a hexagonal head that is compatible with various types of clips and strips for pipes. Type M8 refers to the thread diameter of 8 mm – this diameter is standard for anchoring installation materials in building structures and provides sufficient strength for the weight load of typical heating systems.

From a practical perspective: when working with a concrete or brick base, always use appropriate plastic anchors (e.g., 8 mm) and tighten the screw evenly, not with excessive force – cracking of the anchor is common in case of over-tightening, and the screw will then hang loosely. For gypsum board, use special SK anchors or anchor directly into the load-bearing profile. For wood, a correct screw length (at least 40 mm into the wood itself, not including the thickness of the gypsum board or cladding) is sufficient.

Thermal expansion of PB pipe – how it affects the selection and placement of aids

This is a topic that most plumbers in the heating industry intuitively understand when working with copper, but often underestimate when working with PB material. Polybutylene pipe has a thermal expansion coefficient of around 0.13 mm/(m·K) – this is roughly seven times more than copper pipe. What does this mean in practice?

A ten-meter run of PB pipe that heats up from 20 °C to 70 °C (a typical difference between a cold and a warm system) will expand by:

10 m × 50 K × 0.13 mm/(m·K) = 65 mm

That is 6.5 cm! This expansion has to go somewhere. If all clamps are fixed without compensation, the pipe will bend or push against fittings and valves. There are two solutions:

Fixed points (fixings): locations where the pipe is fixed immovably – usually at each branch or fitting
Sliding points: other clamps and strips that only guide the pipe, but allow axial movement – with a strip system this is automatic, with clamps it is necessary to use a type that does not seal against the pipe

For a detailed discussion of expansion compensation and the installation of fixed loops, see the article How to correctly install a fixed loop for pipe 15–18 mm.

Practical scenarios from everyday installation practice

Scenario 1: Single-family house, two-pipe system, pipe Ø15 mm

This is by far the most common case. A wall-mounted boiler in the boiler room, two parallel pipes (supply + return) lead from the boiler to the manifold, then to individual rooms. The total length of the distribution in the building is around 60–80 m.

For such an application, I would choose strip 16 mm every 600 mm along horizontal routes and every 800 mm on vertical risers. With two parallel pipes, strips are more practical than clamps, as two strips can be installed side by side on one mounting profile, or double-pipe strips can be used. At the transition from PB to copper pipe at the boiler, I would use copper pipe transition 15×1 EK for copper pipe, and fix the strips using KOMBI M8 screws into the concrete core of the wall through plastic anchors Ø8.

Scenario 2: Attic reconstruction, mixed system PB + older copper piping

This is a situation where Hepworth PB is connected to existing copper piping – typically when only part of the house is being renovated. It is crucial to choose the right transition elements here. If the new PB section (Ø15 mm) connects directly to a copper pipe of the same diameter, we use transition 15×1 EK for copper or PB pipe, as this combination is specifically intended for such a transition. For fixing the route in the attic (where there are mostly wooden beams), we choose clamps with pre-drilled holes and screws of sufficient length – at least 40 mm into wood.

Scenario 3: Technical room, dense distribution with multiple primers

In a technical room with a boiler, storage tank, water heater, and multi-way manifold, different diameters converge. PB 15 mm, PB 18 mm, copper 22 mm – all routes run closely next to each other. Here, a systematic strip system is a great advantage. Strip 16–18 mm covers both PB dimensions, so there is no need to mix multiple sizes. KOMBI M8 screws are consistent for all types of fixing, which simplifies material supply and speeds up work on site.

Most common mistakes in selection and installation – and how to avoid them

After years in the field, I have compiled a kind of "shame list" – mistakes that repeat themselves regardless of how much experience the plumber has. I list them here not to shame anyone, but because each of them can cost the customer a service call and the plumber a good reputation.

Mixing internal and external diameter: The customer orders a strip "for 15 mm" and means the internal diameter. The strip is then too tight or, on the contrary, too loose. Always specify the external diameter.
Omitting sliding points: Tightening all clamps to the maximum = the pipe will bend or crack the fitting when heated. Every fixed section longer than 2 m needs compensation.
Using unsuitable transition fittings: Transition fittings for copper pipe on PB and vice versa – the geometry of the conical sealing surface is different. Result: leakage during the first pressure test.
Using anchor screws that are too short or too long: A short screw does not create a secure fixing. A too long screw will punch through water or electrical lines behind the structure. Always determine the thickness of the substrate before drilling.
No expansion protection when passing through a wall: When the pipe passes through a wall or ceiling without an expansion sleeve, the surface of the pipe will wear against the edge of the opening due to thermal expansion.

A comprehensive overview of errors and their solutions can be found in the articles Common mistakes in pipe fixing and how to avoid them and Loose or cracked clamps – causes and solutions.

Comparison of manual vs. mechanical installation and its impact on tool selection

The choice of installation tools also depends on whether the installation is done manually (classic plumber with hand tools) or mechanically (professional nailing and clipping devices). For manual installation, strips with a clamping mechanism and clamps with a standard hole for a screw are suitable. For mechanical installation, special clamps compatible with a nailing tool and a different head geometry are used.

In a domestic environment and for routine jobs, manual installation is the standard and all products in this category are fully designed for it. The topic is discussed in more detail in the article Manual vs. mechanical pipe fixing – differences and use.

Checklist before purchasing installation tools

To ensure you don't forget anything before placing your order, I have prepared a practical checklist of questions you should have answers to:

What is the outer diameter of my Hepworth PB pipe? (Measure with a caliper.)
How many meters of route in total? (For calculating the number of clamps/straps with a 600 mm spacing.)
Is the pipe running horizontally, vertically, or a combination? (Affects the spacing of the mounting.)
What is the base for anchoring? (Concrete, brick, wood, drywall, steel profile?)
Is connection to copper pipe or another material required? (If yes, what diameter and side of the connection?)
Are there long sections without bends (over 2 m)? (If yes, thermal compensation must be considered.)
How many parallel routes are running next to each other? (For deciding between straps and brackets.)
Is the installation manual or machine-assisted?

Frequently Asked Questions (FAQ)

Can I use a 16 mm diameter bracket for a Hepworth PB pipe with an outer diameter of 15 mm?

Yes, this bracket is specifically designed for that. The Hepworth pipe with an outer diameter of 15 mm has an actual outer diameter of 14.9–15.1 mm with the appropriate tolerances, and the 16 mm bracket provides the correct clearance for trouble-free insertion and at the same time sufficient compensation for thermal expansion without the pipe swaying freely. Do not use a 16 mm bracket for a 18 mm pipe – it would be too tight.

How many expansion joints do I need for the entire project and how do I calculate them?

A simple rule: one expansion joint = one transition point between two different materials or systems. Count all the places where the PB pipe connects to a copper pipe, brass valve, fitting block, or threaded connection. Each such place = one expansion joint. Do not forget that in a two-pipe system (supply + return), the number doubles.

Can I use any screws I have on hand for the PB pipe, or do I need to use a specific type?

Technically, there is no absolute ban on using another type of screw if it has the correct diameter and length. However, the KOMBI M8 screw is designed with a combination of slot and hex head, which simplifies installation in tight spaces (a cross-head screwdriver or flat wrench can be used). Low-quality screws made of galvanized soft steel may corrode over the years in a wet environment and cause the mounting to loosen. For long-term durability of the installation, it is worth using the right products.

Bracket or strap – what is cheaper and what is better?

A direct price comparison per piece can be misleading. Brackets are cheaper per mounting point, but they need to be anchored at a smaller spacing, since each bracket is a shorter fixed section. Straps are more expensive per piece, but for long straight runs with larger spacing, the total number of pieces may be lower. In terms of mounting quality and surface-friendliness to the PB pipe, brackets with a soft contact profile are a slightly better choice. Straps, on the other hand, provide a more secure mounting at a single point – important for fittings and bends, where we do not want the joint to move.

What happens if I install too few straps or brackets on a long run?

With PB pipe (and more so than with copper), visible sagging will occur – the pipe will sag between mountings into an arc. The aesthetic issue is minor – the bigger risk is that prolonged sagging causes permanent deformation of the material (so-called creep), and the pipe permanently changes shape. With temperature cycles, mechanical stress will appear at the strap or bend locations. Correct spacing is an investment in the lifetime of the entire system.

How can I check if the expansion joint is properly sealed after installation, without pressure testing?

Visual inspection: the nut should be evenly tightened, without visible twisting (rotation) of the pipe. The end of the pipe must be clearly pushed in to the stop. After filling the system with water and bleeding it, check each joint with a dry paper towel – even the slightest moisture will be immediately visible. Formal pressure testing is mandatory for every new installation and we recommend it at 1.5 times the operating pressure for at least 30 minutes before covering or plastering the run.

Conclusion – the right choice always pays off

Mounting accessories for Hepworth pipe may seem like a minor detail, but in reality, they are a crucial part of every heating installation. A correctly chosen bracket, adequate expansion joint, and firmly anchored screw make the difference between a system that reliably works for 30 years and a system that requires service visits every two seasons.

The principle is simple: know the diameter and material of your pipe, respect the physical properties of PB (especially thermal expansion), use products specifically designed for the Hepworth system, and do not underestimate anchoring. An investment in the right tools always pays off – in the form of trouble-free operation, savings on service, and a long lifetime of the entire system.

If you are unsure about any point, further detailed articles in the Knowledge Center category of mounting tools will guide you through each related topic – from choosing the correct diameter to solving loose straps in operation.

Do you have a question about this topic?

Not sure how to proceed or dealing with a specific situation in your home? Write to us – we are happy to help.