Step-by-step installation of HEPWORTH piping for heating

We are still preparing products.

But you can look at other categories.

Installation of HEPWORTH pipe for heating step by step

Plastic pipe HEPWORTH has become a standard in the installation of modern heating systems – and for good reason. It is light, corrosion-resistant, flexible and, when installed properly, lasts for decades. Despite this, in every second case we deal with, some kind of error in the installation appears – a loose fitting, a poorly prepared pipe end, an unsuitable diameter or simply a skipped step. This article is therefore a practical guide – not a catalog presentation – but a real procedure on how to install HEPWORTH heating pipe correctly, without subsequent problems.

Before you start the installation, we recommend reading other topics in our Knowledge Center – for example How to choose the right HEPWORTH pipe for heating or What pipe diameter do I need for heating: 15, 22 or 28 mm. If you know what you are installing and why, the installation itself goes much smoother.

What to prepare before installation – materials, tools and plan

Good installation starts at the table, not at the wall. The first thing to do is to sketch a layout of the entire piping system – where the main supply from the boiler runs, where the distributors are, where the individual heating circuits are and where the radiators or floor heating loops are. Only based on this layout you can realistically calculate how much pipe you need and in which diameters.

For a typical family house, the following distribution applies roughly: the main distribution pipe from the boiler to the distributor is typically 22 mm in diameter, sometimes even 28 mm in more powerful systems or longer routes. Connections to individual radiators are almost always 15 mm. This is not a manufacturer's recommendation – this is the result of hundreds of projects.

Basic tools

Pipe cutter (plastic pipe cutter, not a saw – more on that later)
Chamfer tool for deburring the inside of the pipe
Roundening tool (calibrator) – especially important for pipe from coils
Mounting pliers or wrench for fittings (depending on the connection system)
Tape measure and pencil for marking
Bender for plastic pipe (especially for installation in pipes)
Fixing clamps and brackets according to the chosen route

Choice of pipe form – coils or straight lengths

HEPWORTH supplies heating pipe in two formats. Pipe in straight lengths 15 mm or 22 mm is ideal where you need longer straight sections – for example in a technical room, boiler room or for wall-mounted distribution. Pipe in coils is, on the other hand, advantageous for long routes, floor heating or anywhere bends are needed. More about this choice can be found in the article HEPWORTH pipe in coils vs. in straight lengths – what to choose.

Step 1 – Measuring and planning the route

This is the step that most "experienced" installers skip and later regret. Draw the entire route on paper or in a simple sketch – with marked lengths, number of elbows, branches, wall and ceiling accessibility. Also calculate the need for expansion loops on long sections – plastic pipe expands by about 0.9–1.2 mm per meter for every 10 °C temperature change when heated to 70–80 °C. A concrete example: a 10 m section heated from 20 °C to 70 °C (delta T = 50 °C) will extend by about 4.5–6 mm. That may not seem like much, but in a closed row without compensation it can cause deformation and pressure on the joints.

At the same time, mark where the fixed points (fixed clamps) and where the sliding support (sliding clamps) will be. Golden rule: for pipe from straight lengths, install a fixed clamp every 1.0–1.2 m (for DN 15), or every 1.3–1.5 m (for DN 22). Sliding clamps between them can be more frequent – every 0.5 m – but the fixed ones determine where the pipe does not move and where the expansion loops are.

Step 2 – Cutting the pipe

This is technically a simple step, but it is often done incorrectly. HEPWORTH plastic pipe must be cut exclusively with a plastic pipe cutter (pipe cutter), not with an iron saw, not with an angle grinder and not with a hand saw for wood. Why? Because a saw creates an irregular, jagged, uneven cut – and such a cut simply does not seal properly in a fitting. A rotating pipe cutter gives a clean, perpendicular cut in a few seconds.

The procedure is simple: put the cutter on the pipe at the cut point, turn it 1–2 times, slightly pull the blade and repeat until the pipe is cut through the entire diameter. Do not press too hard – let the plastic pipe cut slowly. Forceful pressure causes deformation of the pipe end.

Step 3 – Calibration and Chamfering of the Pipe End

These are two steps that most installers either do only one of them or skip both. Yet they are crucial for the tightness of the joint.

Calibration (Rounding)

Pipe from coils is twisted, which means the ends are not perfectly round – they are slightly elliptical. Such an end will fit into the fitting, but the seal will not work evenly around the entire circumference and will eventually start to leak. A calibrator (roundening tool) is simply inserted into the end of the pipe and rotated – with moderate force, it corrects the ovality into a round cross-section. Calibration is less critical for pipe from straight bars, but it won't hurt.

Chamfering

The inner edge of the cut has a sharp edge. A chamfering tool (chamfer tool) gently bevels this edge at an angle of approximately 15–20°. Without this step, the sharp edge can damage the sealing in the fitting or prevent full insertion. Just 3–5 strokes with the tool are enough – you can then verify the result with your finger: the inner edge of the pipe must be soft, without sharp edges.

Step 4 – Inserting into the Fitting and Pushing In

HEPWORTH uses a push-fit fitting system, which means you do not need any glue, soldering, or gas torch for connecting. The procedure is as follows:

Mark the insertion depth. Each fitting has a defined insertion depth – for DN 15 it is typically 20–22 mm, for DN 22 it is approximately 24–26 mm, for DN 28 it is approximately 28–30 mm. Measure and mark this depth with a marker directly on the pipe. Without this visual reference point, you won't know whether you have pushed the pipe in sufficiently.

Insert the pipe into the fitting with one smooth motion. Do not start shaking or rotating repeatedly – insert it straight and firmly until you feel a "click" or until the mark on the pipe reaches the level of the fitting face. This click is the collet (retaining ring), which locks onto the pipe and holds the joint under pressure. If you have marked the insertion depth and you see that the pipe only reaches half of this depth, you must push it in further.

Verify the locking with a light pull. After insertion, try to gently pull the pipe out – it must not move. If it moves, repeat the insertion, or check whether you have properly calibrated the end. If the pipe still does not hold in the fitting after calibration and chamfering, the problem may be a damaged collet or an incorrect fitting for the given size.

Disassembly and Reuse of the Fitting

Push-fit HEPWORTH fittings can be disassembled using a release ring (release tool), which compresses the collet and allows the pipe to be removed. This is a major advantage over soldered joints – if you make a mistake in the direction, you do not have to cut, just disassemble and adjust the route. But be careful: each subsequent installation of the fitting increases the risk of micro-damage to the seal. In practice, we recommend using each fitting no more than 2–3 times and replacing it if there is any suspicion of seal damage.

Step 5 – Routing the Pipe, Bends and Support

HEPWORTH pipe is flexible enough to be shaped without a special bender – but only up to a certain radius. The minimum bend radius (without a bender) is approximately 5× the outer diameter for DN 15, which with an outer diameter of 20 mm results in a minimum radius of 100 mm. If you bend it sharper than that, the pipe may flatten and narrow at the bend – this increases pressure loss and in a more powerful system may cause noise or insufficient flow.

With pipe bar stock, a bender is necessary for each elbow – an alternative is shaped fittings (45° or 90° elbows), which are structurally rigid and do not change the pipe diameter at the point of directional change. In practice, we combine both approaches: elbows for regular straight runs, and a bender where the route is more complicated or where fewer joints are desired.

Mounting the pipe to the wall or ceiling

Every pipe run must be regularly secured to prevent unintentional movement, vibrations, and mechanical stress on the joints. The spacing of clamps was mentioned above – we also want to add that clamps must always be mounted perpendicular to the pipe axis and must not be tightened in a way that mechanically compresses the pipe (which would cause localized stress).

For pipes behind plaster or in a concrete slab, special rules apply: the pipe must be inserted into a protective sleeve (corrugated tube) to allow space for expansion. Without this precaution, you will hear cracking and clicking in the ceilings and walls during the first start-up – and we are not talking about a fault, but about normal thermal expansion that has nowhere to go.

Step 6 – Filling, bleeding and pressure test

After completing all joints and securing the pipe, the system is filled with water. Before filling, we recommend a visual inspection of each joint – check whether all fittings are inserted equally, whether nothing looks "crooked," and whether no fitting is visibly damaged.

Filling procedure

Open the filling valve and let water slowly enter the system at low pressure (0.5–1 bar).
Start from the lowest point of the system and proceed upwards – air will naturally rise to the bleed valves.
Open the bleed valve on each radiator one after the other – until water flows out without bubbles.
After bleeding, increase the pressure to the operating level (typically 1.5–2.5 bar for single-family homes).
Leave the system under pressure for at least 30 minutes and check all joints for leaks.

Pressure test

For newly built systems or after major reconstruction, a pressure test with water is recommended (and for some types of jobs, it is mandatory). The system is pressurized to 1.5 times the maximum operating pressure (for example, 3.0 bar for a system with an operating pressure of 2.0 bar) and left under pressure for 30–60 minutes. Any pressure drop indicates a leaky fitting or a damaged section of pipe. An advantage of the push-fit HEPWORTH system is that a leaky spot is usually easily located visually (drops) and quickly repaired by replacing the fitting.

Step 7 – First Commissioning

After a successful pressure test, the first boiler start-up and real heating of the system follows. Here are a few things to pay attention to:

Watch the joints during the first heating. When the water heats up, the pipe thermally expands and starts to work. Any improperly inserted fittings will be revealed in this phase – water will start to drip. Do not check the joints visually only, but also with a paper towel at each joint – if it gets wet, the joint is leaking.

Check for new air pockets. Sometimes air is released from the water during the first heating and collects in various places in the system – this is noticeable in radiators as uneven heating (the top part of the radiator is cold). Bleed the system again.

Check the pressure setting of the expansion tank. Plastic pipe is less rigid than copper, which means the thermal expansion of the system is higher. The expansion tank must be properly sized – if it is too small or the pre-pressure is incorrect, the safety valve will discharge water with every heating cycle.

Step 8 – Photo Documentation and Tracing Before Covering

This is a step that is often skipped on most jobs with the justification of "I remember it". Five years later, when the customer is dealing with a repair, no one will remember anything. Before covering the pipe with plaster, drywall or other cladding, take photos of the entire route – with a scale or measured from fixed points (wall corner, window, door). The customer will store these photos together with the installation technical sheet. If you want to formalize it, you can also draw a simple layout with dimensions.

This seemingly unnecessary work will save several hours of cutting plaster in the event of a future failure or renovation. Customers for whom we have done this always return – and customers for whom no one did it and came to us during a failure will never forget.

Most Common Installation Mistakes and How to Avoid Them

Over the years of contract work, certain mistakes repeat so regularly that it is worth mentioning them specifically. A more detailed discussion of them is in the article Common Mistakes in the Installation of Plastic Pipes for Heating, here we list those directly related to the installation procedure:

Cutting with a saw instead of a pipe cutter: Uneven cut → leakage. Always use a rotating plastic pipe cutter.
Skipping calibration on pipe from reels: Oval end of the pipe will not seal. Always calibrate.
Insufficient insertion depth: The joint holds, but only on the collet, not on the sealing ring. Always mark the insertion depth.
Missing expansion loops on long sections: The pipe thermally expands and deforms the joints or clamps.
Pipe embedded in concrete without protective sleeve: Concrete holds the pipe firmly, thermal expansion has nowhere to go – mechanical stress on the joints.
Mixing DN 15 and DN 22 fittings: The outer diameters are similar, but the fittings are not interchangeable. Always check the marking on the fitting.

Special Situations – Renovation, Route Interruption, Connection to an Old System

Not every installation is a new build with a clean slate. In most cases, it is a renovation of an existing system, where HEPWORTH is connected to an older copper, steel or other plastic pipe system.

Connecting HEPWORTH to Copper Pipe

HEPWORTH offers transition fittings from compression to push-fit (and vice versa), so connecting to copper pipe is technically simple. However, you must remember that copper pipe has different outer diameters than plastic HEPWORTH – for example, Cu 15 has an outer diameter of 15 mm, while HEPWORTH DN 15 has an outer diameter of 20 mm. Always use a transition fitting Cu × HEPWORTH, not force a fit.

Connecting to a Steel Threaded Pipe

When connecting to an old steel threaded system, use a transition fitting with a threaded and push-fit end. The thread must be clean, free of corrosion, and sealed with hemp or Teflon (not silicone, which is not suitable for heating). Make sure the transition fitting is fixed against rotation – when tightening the thread, you might accidentally rotate the push-fit part and stress the joint.

Route Interruption – Inspection Opening

If for any reason you have to interrupt a route that runs through a covered area (under the floor, in drywall partitions), always solve the interruption via an inspection opening. In most cases, heating regulations require that every joint be accessible – meaning the pipe can be fully covered (without a joint), but every fitting must be accessible. This has a crucial practical significance in the case of failures or later repairs.

Differences Between Heating Installation and Water Supply Installation

You might wonder – since HEPWORTH also makes HEP2O pipe for water supply, is the installation the same? The technical procedure is very similar, but there are important differences. HEPWORTH heating pipe is designed for higher temperatures (up to 95 °C short-term) and working pressure up to 10 bar, while the material (PERT type II or similar) is thermally more stable. HEP2O water pipe is also multi-purpose, but for long-term operation at 70–80 °C, we recommend using pipe specifically designed for heating. You will read more about this in the articles Difference Between HEPWORTH and HEP2O Pipe for Heating and Using HEP2O Pipe for Heating and Water Supply in One System.

Practical Examples from Practice

Example 1 – New Single-Family House, Two-Loop System

A typical job: a two-story single-family house, 24 kW condensing gas boiler, two separate loops (ground floor and upper floor), each loop connected via its own pump circuit. Main boiler–distribution pipe: HEPWORTH 22 mm in a length of approx. 6 m. Radiator connections: HEPWORTH 15 mm in bars (simple straight routes along the walls, fixed with clips 80 cm apart). On a long section around the ground floor (total 22 m), we designed two expansion U-loops with 120 mm space – during system heating, the loops will absorb the expansion without stressing the joints.

Example 2 – Apartment Renovation, Connection to Original Steel Staircase

An older job from an apartment building – original steel vertical pipes DN 20, new layout in the apartment. Connection solved with transition fittings G3/4" external thread × HEPWORTH push-fit 22 mm. The entire in-apartment layout made of HEPWORTH 22 mm and HEPWORTH 15 mm run under new floors in a protective sleeve made of PE-HD pipe (one size larger than the pipe). Result: pressure test at 4 bar with no drop for 60 minutes, no problem areas during first heating.

Example 3 – Floor Heating, Pipe from Reels

For floor heating, pipe from reels is an obvious choice – one reel can cover the entire loop without joints, which is a crucial advantage (minimizing the risk of leakage in a concrete slab). For each loop, 15 mm pipe is used, total lengths 60–120 m depending on the room area. In this application, calibration of both ends of the pipe (when connecting to the manifold) is even more important, since repairing a leak under tiles is extremely costly.

Pressure and Temperature Limits – What the System Can Withstand

HEPWORTH heating pipe is dimensioned for an operating temperature up to 70 °C at a maximum pressure of 10 bar, and short-term (in emergency situations) up to 95 °C. For standard low-temperature heating (45/35 °C) or even for standard heating (70/50 °C), the pipe therefore operates with a significant margin. Fittings are dimensioned the same, so the weakest link in the push-fit system is not the fitting, but the quality of the installation – specifically the preparation of the pipe end and the insertion depth.

For systems with temperatures above 80 °C (e.g. old "hot water" installation or heat pumps with peak heating), check with the technical data sheet of the specific product before installation to confirm that HEPWORTH is suitable for the intended application. In some cases, it may be more appropriate to use copper or steel pipes for the main lines and HEPWORTH only for the parts with lower temperatures.

Frequently asked questions (FAQ)

Do I need to use any lubricant on the fittings when installing HEPWORTH piping for heating?

No, HEPWORTH push-fit fittings are not intended to be lubricated during installation. The sealing (O-ring) is designed to function dry. Using an unsuitable lubricant (e.g. silicone or vaseline) may damage the seal or reduce its lifespan. If insertion is difficult, check whether you have correctly bevelled the inner edge of the pipe end – this usually significantly eases insertion.

Can I reuse HEPWORTH push-fit fittings – for example when rerouting the pipe?

Yes, the fittings can be disassembled using a release tool (demounting ring) and reused. However, we recommend visually inspecting the seal after each disassembly – if the O-ring is deformed, cut or discoloured, replace the fitting. You can safely perform 2–3 disassemblies; after the third one, it is cheaper to replace the fitting than to risk a leak.

What is the difference between HEPWORTH 15 mm in coils and HEPWORTH 15 mm in straight lengths – is the installation different?

The installation procedure is the same – cutting, calibrating, beveling, and inserting. The difference is that pipe in coils is slightly oval before installation and always requires calibration. Pipe in straight lengths is round and straight, which simplifies work in straight sections and when running along walls. On the other hand, coils are more convenient for long runs and underfloor heating, where you want to minimize the number of joints. Read more in the article HEPWORTH pipe in coils vs. in straight lengths – what to choose.

How can I detect a leak before covering the system?

A pressure test is the only reliable method. Pressurize the system to 1.5× operating pressure and wait at least 30 minutes – monitor the pressure gauge. Any pressure drop (even a small one) indicates a leak. In case of suspicion, try wiping the joint with a dry paper towel or use a leak detection spray – it will foam even with minimal gas (in a gas test) or moisture. Always cover the piping only after a successful pressure test – never before.

Can I bend HEPWORTH heating pipe manually, or do I need a special bender?

For DN 15, manual bending is possible to a radius larger than 100 mm (5× outer diameter). For DN 22, the minimum safe radius for manual bending is approximately 165 mm. Bending below these values risks flattening and narrowing the cross-section, which impairs flow. For sharper direction changes, use angled fittings (45°/90° elbows) or a plastic bender with an internal spring that prevents flattening. For straight lengths, elbows are almost always a better choice than manual bending.

What to do if I find multiple leaks during the pressure test?

First, check whether the leak is coming from only one location, and you may have missed it during the visual inspection (water can run along the pipe far from the source). Address each leak separately: disconnect the pipe from the fitting, check the pipe end (ovality, sharp edges, damage), check the O-ring in the fitting, and replace the fitting if necessary. If there are many leaks, go back to the basics – check whether you have the correct calibrator for the given diameter, whether all ends are bevelled, and whether the insertion depth corresponds to the required depth. Typically, in 80% of cases, the same missed step in pipe preparation causes multiple leaks.

Conclusion – summary of key principles

Installation of HEPWORTH heating pipe is not technically demanding, but it requires attention to detail. Every missed step – whether it is calibration, beveling, or not marking the insertion depth – can result in a leak that you will only discover after covering the piping. This is many times more expensive to fix than spending an extra 30 seconds per joint.

If you are unsure about pipe sizes or the type of pipe for your specific system, check other articles in our Knowledge Centre – for example What pipe diameter do I need for heating: 15, 22 or 28 mm or Frequently asked questions about HEPWORTH heating pipe. A well-planned and carefully executed installation with HEPWORTH pipe will last you many years without problems – and that is exactly what every customer rightly expects from a heating system.

Do you have a question about this topic?

Struggling to decide or dealing with a specific situation in your home? Write to us – we are happy to help.