Installation of HEPWORTH copper pipe: soldering or crimping
Copper pipe HEPWORTH: Soldering or Compression – Complete Technical Guide
Copper pipe is among the oldest and most reliable materials for potable water distribution in both apartment and single-family homes. Anyone who has worked with older installations knows that copper can easily last 50, 60 or more years – provided it was properly installed. And this is where the challenge lies: the same material can be joined using several different technologies, each with its own requirements in terms of skill, tools and time. In this article, we will focus on the two main methods used for HEPWORTH copper installation – soldering (soldering) and compression (pressing). We will examine both methods in depth, compare them in general and in specific situations, and help you decide which is more advantageous for your particular project.
If you are still in the stage of selecting materials and considering whether to go with copper or rather with multi-layer pipe, I recommend reading the article Multi-layer pipe vs. HEPWORTH: which is better for your distribution, where both materials are compared in terms of overall costs and suitability for use. Here we will assume that the decision for HEPWORTH copper has already been made, and we will focus exclusively on the joining technology.
What is HEPWORTH pipe and why it is used
The brand HEPWORTH (now part of the Wavin group) is synonymous with high-quality copper pipe for potable water, gas and heating distribution in Central Europe. HEPWORTH water pipe 15 mm in a coil 50 m is the most sold format for apartment distribution of cold and hot water – this dimension corresponds to the standard household installation for supplying taps, showers and toilet cisterns. For main vertical lines, connecting branches to water heaters or for households with higher consumption, HEPWORTH 22 mm in a coil 50 m is commonly used, which covers a higher flow without unacceptable pressure losses.
Copper pipe has several properties compared to plastic alternatives that are relevant for potable water: natural bacteriostatic effects (copper ions suppress the growth of bacteria including legionella), resistance to UV radiation, long service life when properly dimensioned and compatibility with high temperatures. More on material safety can be found in the article Hygiene and material safety of pipe for potable water: what you need to know.
Soldering copper pipe: principle, technology and procedure
Soldering (sometimes also called soldering) is a technology in which the connection of two pipe sections is created using molten solder that enters the capillary gap between the pipe and the fitting. It is not welding – the base material does not melt, only the solder. The capillary effect ensures that the molten solder spreads evenly around the entire circumference of the joint, which when done correctly results in a watertight and strong connection.
Soft vs. hard soldering
In practice, soft soldering is almost exclusively used for potable water distribution (soft soldering in English), where the temperature does not exceed 450 °C. The solder must be lead-free for potable water – the standard is Sn97Cu3 (97 % tin, 3 % copper) or Sn99Cu1. This solder is approved for contact with potable water according to current standards (STN EN 12502, EN 1254). The flux must also be neutral and water-washable to ensure that no aggressive residues remain inside the pipe after soldering.
Hard soldering (brazing, temperature above 450 °C, usually 600–900 °C) is used exceptionally for potable water distribution – more often for pressure systems, cooling or gas pipelines. It is not necessary for standard apartment installation with HEPWORTH pipe and is much riskier for a layperson.
Step by step: procedure for soft soldering HEPWORTH
1. Cutting: HEPWORTH pipe is cut exclusively with a copper pipe cutter – never with a file or angle grinder, as these leave metal shavings that could contaminate drinking water and potentially damage valve seals. The cut must be precisely perpendicular to the pipe axis. After cutting, the inner opening is cleaned of burrs using a deburring tool (usually integrated in the cutter).
2. Cleaning: This is a step that amateurs often underestimate. The outer surface of the pipe within the insertion length into the fitting (usually 10–15 mm depending on the diameter) and the inner surface of the fitting must be thoroughly cleaned with a wire brush or special abrasive cloth. Copper oxidizes quickly – even a seemingly shiny surface may have a thin oxide layer that will repel the solder. You clean both chemically and mechanically.
3. Applying flux: Flux (a pasty substance) is applied in a thin, even layer with a brush to both cleaned surfaces. The role of flux is to remove oxides from the copper surface during heating and reduce surface tension so that the solder can evenly penetrate the capillary gap. After applying the flux, the pipe must be immediately inserted into the fitting and rotated to evenly distribute the flux.
4. Heating: A flame (propane-butane or acetylene torch depending on the diameter) is used to heat the fitting – not directly at the point where you apply the solder. The fitting has a higher thermal capacity and heats more slowly. When it reaches the correct temperature (approximately 180–220 °C for soft solder Sn97Cu3), the flux begins to bubble and darken. This is the signal.
5. Applying the solder: The solder wire is placed against the edge of the fitting on the side opposite the torch. If the temperature is correct, the solder is drawn into the gap by capillary action without being melted directly by the flame. This condition is crucial – if you melt the solder directly with the flame, it will only cover the surface and not penetrate inside, resulting in a leaky joint. Apply as much solder as corresponds to the circumference of the joint – approximately 1× the pipe diameter in millimeters equals about that many centimeters of solder wire (e.g., for ∅15 mm, approximately 1.5 cm of solder wire).
6. Cooling and inspection: The joint is allowed to cool naturally – never cool it with water (thermal shock can damage the joint). After cooling, wash the flux away with water, as even neutral flux can cause corrosion over time. A pressure test follows – standard is 1.5 times the working pressure for 30 minutes.
Tools required for soldering
- Copper pipe cutter (e.g., for ∅15 and ∅22 mm)
- Deburring tool (internal and external – cutting or conical)
- Copper wire cloth or abrasive paper P120
- Propane-butane torch with adjustable flame (for ∅15–22 mm, 1.8–2.5 kW is sufficient)
- Lead-free solder Sn97Cu3 in the form of wire ∅2 mm
- Flux/solder for drinking water (water-soluble, neutral)
- Brush for applying flux
- Thermal insulation pad / reflective plate (when working near wood or insulation)
Pressing copper pipe: principle, technology and procedure
Pressing (or pressing) is a relatively newer technology for joining copper pipe, which became widely used in the 90s of the last century. The principle is mechanical: a special fitting with an integrated O-ring seal is slid onto the pipe and, using pressing pliers (manual or hydraulic), it is deformed into a precise geometry that ensures a mechanically strong and sealed connection.
Unlike soldering, you do not need any heat, flux, or solder here. You can make the joint even on a wet pipe (which is absolutely impossible with soldering), and this is a huge advantage in practice for repairs and renovations. Pressable fittings for copper are recognizable by visible O-rings and characteristic embossing that appears after pressing.
Types of pressing profiles
The most common pressing profile for copper is the M profile (or TH) according to the EN 1254-7 standard. Some manufacturers use proprietary profiles (e.g., Viega Profipress, Geberit Mapress) – these fittings and pliers are not interchangeable. You must always use pliers compatible with the specific fitting. Interchanging pliers is one of the most common mistakes made by installers.
Step-by-step pressing procedure
1. Cutting and deburring: Identical to soldering – copper pipe cutter, perpendicular cut, removal of burrs. Burrs are especially dangerous in pressing, as they can damage the O-ring during insertion.
2. Inserting the pipe into the fitting: Insert the pipe into the fitting until it reaches the stop (most fittings have an internal stop or inspection window). This is a critical step – if the pipe is not fully inserted, the O-ring will not be in the correct position and the joint will be leaky. Many fittings have side inspection holes through which you can see if the pipe has reached the stop.
3. Pressing: Mount the correct plier jaw onto the fitting (the jaw must match the profile and diameter of the fitting) and press the trigger of the pressing pliers. Modern battery-powered pressing pliers (e.g., Rems, Viega, Rothenberger) usually emit an acoustic signal after completing the full stroke. The entire cycle takes 2–6 seconds depending on the diameter.
4. Visual inspection: After pressing, check whether the hexagonal (or other appropriate) profile is evenly embossed around the entire circumference of the fitting. If you see a spot where the fitting was not pressed (lack of deformation), the joint must be cut out and a new one made. It is not possible to repair an improperly pressed joint – fittings cannot be pressed twice.
Tools required for pressing
- Copper pipe cutter
- Deburring tool
- Battery or hydraulic pressing pliers
- Set of jaws compatible with the corresponding fitting brand (e.g., profile M/TH for ∅15, 22, 28 mm)
- Depth gauge for insertion (optional, but recommended)
Comparison of Soldering and Crimping: A Practical View
In this section, we will look at both technologies through the prism of the most important criteria that decide real projects.
Costs: The difference is greater than it seems
Soldering is cheaper in terms of materials – a standard copper solder fitting (e.g., 15 mm elbow) costs about 0.40–0.80 €, while the same crimp fitting costs from 1.80 to 3.50 € depending on the manufacturer and sales channel. For a project with 80 joints (a typical single-family house), the difference is several hundred euros. On the other hand, crimp pliers are an investment of 500–2000 € (premium battery-powered models), and for a one-time project, renting them (about 20–60 €/day) is a more reasonable choice than buying.
A professional plumber who does dozens of projects a year quickly pays off the cost of the pliers – saving time on installation and labor hours. For a DIY homeowner who does installation once every 20 years, soldering is more economically advantageous, but they must have the necessary skills.
Installation speed: Crimping has no competition
An experienced plumber with crimp pliers can make a joint in 30–60 seconds including preparation. Realistically, soldering one joint takes 3–5 minutes (surface preparation, flux, heating, solder, cooling). If you have 100 joints in the entire house, we are talking about a difference of 5 hours of work versus 8–9 hours. On larger projects (apartment buildings, renovations), the savings are even more significant.
Where soldering has no competition
A soldered joint is materially monolithic – copper and solder form a solid metal connection without any elastomeric components. This type of joint, when properly made, is practically durable for the entire pipe lifetime (50+ years). A crimped joint depends on the integrity of the O-ring, which is made of EPDM or FKM rubber. Although manufacturers state the O-rings have a lifetime of 50 years under normal conditions, in practice, aggressive water (chlorine, softened water with low pH) can accelerate the aging of the elastomer. For long-term hidden installations in walls without access, soldering is theoretically more reliable – although this is not a reason to avoid crimping in a properly dimensioned installation.
When to choose soldering and when to choose crimping: decision scenarios
Scenario 1: Renovation of a bathroom in a panel apartment
This is a case where crimping clearly wins. In a panel building, you are working in a confined space where an open flame is problematic in terms of fire safety and insurance. In addition, you will likely connect the new layout to the existing piping, where residual water can complicate or prevent soldering. Crimping in a wet environment is problem-free.
Scenario 2: New construction of a single-family house with a complete water layout
Here you have time, you are working in a dry environment, the scope of work is defined, and the installation is done before the grooves are embedded in the walls. If you are an experienced craftsman or professional plumber, soldering is economically reasonable here and provides the most durable installation. For a less experienced homeowner or subcontractor with less experience, crimping is a safer choice in terms of joint quality.
Scenario 3: Emergency repair of a broken pipe
The pipe has cracked, water is leaking, and it needs to be fixed quickly. Here there is no other option but crimping (or mechanical self-sealing couplings) – soldering a wet pipe is impossible without long drying, which simply does not work in an emergency situation.
Scenario 4: Minor repair in a technical room or boiler room
In the boiler room you have space, a dry environment, and are working on visible piping. If you have a torch and the skill, soldering is perfectly fine here. If not, rent compression pliers – it will be cheaper and faster than repeated visits to the plumber.
Combining both technologies in one installation
In practice, it is not uncommon for one installation to combine both types of joints. For example, the horizontal distribution in the technical room is soldered, while the vertical pipe runs in a wall groove and there the joints are compressed. Or a new distribution is fully compressed, but the connection to the old installation is made using a transition fitting (a soldered sleeve on the side of the old pipe, threaded or compression end on the new side).
Important rule: you must always know where the hidden joints are. In renovations, I recommend documenting the joints in the grooves with photographic documentation and attaching it to the technical documentation of the building. With compression joints it is easier – each joint is identical and easily recognizable. With soldering, it is important to check each joint before the wall is closed.
Dimensioning and selection of diameter for copper piping
Selecting the pipe diameter is just as important as selecting the joining technology. For standard apartment installations, the following basic rules apply: ∅15 mm (∅12 mm for thin-walled EN) for connections to individual fixtures (faucet, toilet, shower), ∅22 mm for main distribution (cold and hot water in the core of the apartment, boiler supply), ∅28 mm and above for vertical pipes or house distribution. A more detailed calculation can be found in the article Dimensioning pipe for drinking water: how to calculate diameter and length.
For comparison – if you are deciding between copper and multilayer piping for a specific project, it may be interesting to look at the parameters of multilayer pipe IVAR Turatec 20x2 in a coil of 100 m, which in the 20 mm dimension is very close to copper ∅22 mm and offers PN10 at temperatures of +70 °C and +95 °C. For smaller distributions, dimensions 16x2 and 18x2 are also available, which are the standard for floor heating and apartment distributions. A comparison of these materials in terms of total costs and usability can be found in the article How to choose pipe for drinking water distribution: multilayer vs. copper vs. plastic.
Most common mistakes and faults during copper pipe installation
Mistakes during soldering
Cold joint: The solder was applied before the pipe reached the correct temperature, or was melted directly with the flame. The result looks rough, dull, with a bubbly structure. Such a joint will not withstand pressure or mechanical stress.
Insufficient cleaning: Flux cannot remove strong oxidation or oily contamination (fingerprints). The solder does not flow into the capillary gap, but remains only on the surface. The joint may look good at first glance, but will leak during pressure testing or later.
Soldering on a wet pipe: Water turns into steam when heated, which pushes out through the soldered gap exactly when the solder is solidifying. The result is microvoids and leaks. The pipe must be dry before soldering – if residual water remains, you can help by using bread (inserting white bread into the pipe, which absorbs the water and dissolves when opened).
Poorly chosen solder: Lead solder (Sn50Pb50 or Sn60Pb40) was commonly available and cheap, but is banned for drinking water. Be careful when buying – always check the composition and certification for contact with drinking water.
Mistakes during compression
Pipe not pushed to the stop: The most common mistake during compression. The O-ring is compressed outside its working position and the joint is immediately or gradually leaking. Solution: always check the insertion through the inspection window of the fitting or mark the insertion depth on the pipe with a marker.
Wrong pliers: Using pliers from another manufacturer or for a different profile. The fitting is mechanically deformed, but not into the correct geometry – the O-ring is not properly compressed and the joint will leak. Always combine fittings and pliers from the same system manufacturer.
Damaged O-ring: A burr at the end of the pipe or dirt can cut the O-ring during insertion. This is not always visible. Therefore, deburring and cleaning the end of the pipe is a mandatory step even during compression.
More about the causes and solutions of faults can be found in the article Common faults and leaks in drinking water pipes: causes and solutions.
Pressure test after installation: how to do it
Regardless of the chosen joining technology, every installation must pass a pressure test before covering (encapsulation, insulation, tile installation). Standard procedure:
- Fill the installation with water and vent it (open air vents or the highest outlet)
- Close all outlets and create overpressure – usually 1.5 times the maximum working pressure (for PN10 it is 15 bar, so the pressure test is 15 bar for 30 minutes)
- In practice, for apartment installations (working pressure 3–6 bar) a test pressure of 9–10 bar is sufficient
- A pressure drop greater than 0.2 bar in 30 minutes indicates a leak
- Visually inspect each joint – a leaking joint will reveal itself either by a drop or by moisture
With soldered joints, it is important to perform the test only after the installation has completely cooled down (at least 1 hour after the last joint). With compression joints, you can perform the test almost immediately.
Most frequently asked questions (FAQ)
Can I solder copper pipe myself, without professional training?
Yes, soldering copper pipe is not a reserved professional activity like gas installation. For drinking water, an experienced DIY enthusiast can do it themselves. However, it is important to fully understand the procedure, use the correct materials (lead-free solder, neutral flux) and perform a pressure test before covering. If you have no experience, we recommend practicing the technique on scrap pipe and fittings before starting the actual installation. Errors in soldering may only become apparent under pressure, sometimes even after months – and behind a wall they are expensive to repair.
Are compression joints approved for drinking water and heating?
Yes. Compression fittings for copper from certified manufacturers (Viega Profipress, Geberit Mapress, Sanha and others) are certified according to standards EN 1254 and DVGW W 544 for drinking water distribution and heating systems up to 120 °C and pressure of 16 bar. It is important that the O-ring is of the correct material: EPDM for drinking water and heating, FKM (Viton) for gas and mineral oils. Using the wrong O-rings can damage the installation.
Can I combine an old soldered installation with new compression fittings?
Yes, and it is common practice during renovations. To connect to an existing soldered pipe, you use a transition fitting: on one side there is a classic solder sleeve, on the other side there is a threaded or compression end. These transition pieces are standard in the range of all major compression system manufacturers. When connecting to the old installation, do not forget to thoroughly clean the old pipe, check the wall thickness and verify that the diameter corresponds to the standard dimension.
What is the difference between HEPWORTH 15 mm and 22 mm pipe and when to use which?
HEPWORTH 15 mm is used for end connections to taps, showers, sinks and toilet cisterns. It is the standard diameter for the last branch of the distribution to the consumption points. HEPWORTH 22 mm is intended for main distribution branches, vertical pipes in the core of the apartment or for boiler and combined appliance supply with higher flow. Simplified: 15 mm for consumption, 22 mm for distribution. When dimensioning, consider the number of simultaneously open consumption points and the required minimum flow rate (0.5–2.0 m/s for drinking water). More can be found in the article What pipe diameter do I need for home water distribution.
Do I need to perform a pressure test on crimped joints?
Yes, a pressure test is mandatory after every installation regardless of the joining technology. Crimping is indeed more repeatable and less prone to human error than soldering, but even with it, you cannot rule out a mistake (e.g., an improperly inserted tube, a damaged O-ring, or incorrect pliers). A pressure test is the only reliable way to verify the tightness of the entire installation before it is covered. Always keep the documentation of the pressure test – it may be needed in the case of an insurance incident or when selling the property.
Is soldering safe in a fiber-cement or wooden structure?
Soldering near flammable materials is riskier and requires increased caution. A reflective (heat-insulating) backing plate behind the pipe is a mandatory tool, as it captures radiated heat and protects the structure. In historic wooden buildings or when installing in grooves with flammable insulation, we recommend preferring crimping. If soldering cannot be avoided, work with a fire extinguisher at hand, inspect the structure 30 minutes after the work and again after an hour – a smoldering fire in the wall can manifest with a delay.
Conclusion: which technology do we recommend?
Neither soldering nor crimping is objectively "better" – each technology has clear situations where it is the right choice. For new construction, where a skilled plumber or experienced craftsman is working and the joints are accessible and dry, soldering is economically advantageous and provides a long-term reliable connection. For renovations, repairs, tight work in apartment buildings, or anywhere speed and safety are paramount, crimping is unbeatable.
In practice, we see an increasing preference for crimping among professional plumbers – not because soldering is bad, but because crimping pliers quickly pay for themselves in saved time, and a crimped joint is easier to verify and document. If you are a homeowner planning a one-time renovation, consider renting the pliers – the cost for a day is negligible compared to the value of a flawless installation hidden behind the cladding for the next 30 years.
Before installation, also read the article Installation of multilayer pipe step by step: tools, procedure, mistakes, where you will find a comparison of approaches to installing multilayer piping – this will help you decide whether copper HEPWORTH or a multilayer system is more suitable for your specific project.
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.