What Is the HEPWORTH System and What Is It Used For

We are still preparing products.

But you can look at other categories.

What is the HEPWORTH system and what is it used for

When a customer comes into our shop asking "what pipe system should I use for heating or water distribution in my flat or family house", the name HEPWORTH comes up quite often - especially with installation companies that already have experience with it from previous jobs. HEPWORTH is the name for a plastic pipe system made of polypropylene (abbreviated PPR, more precisely PP-R - polypropylene random copolymer), used for distributing cold and hot domestic water, heating circuits with radiators, and underfloor heating. So it is not one specific product, but a complete system - pipes, fittings, transitions to metal, manifolds, and joining elements - which are all compatible with each other and can be combined into a functional system from the boiler room to the last radiator in the house.

In practice this means that when you choose HEPWORTH, you are not just buying pipe, but a whole "building block" system - similar to how with electrical wiring you don't just buy cable, but also connectors, junction boxes, and breakers that all have to match each other. This closed nature of the system is precisely one of the main reasons installation companies like it: once trained, an installer can reliably work with the system on any job, because the welding procedure, the size ranges, and the sizing method are always the same.

What the system consists of

The basis is polypropylene pipe in several versions - purely plastic (homogeneous), or with a reinforcing layer of glass fibre or aluminium foil in the middle of the pipe wall. The reinforcing layer significantly reduces the linear thermal expansion of the material, which is considerably higher for pure plastic than for metal. Without reinforcement, PPR pipe heated from 20 °C to 70 °C expands by several millimetres per metre of length, which needs to be accounted for in design with compensation loops or sliding fixings - a fixed point and compensation space is usually recommended approximately every 1.2 metres of straight, uncompensated run. Reinforced pipes (especially with an aluminium layer) have expansion close to that of a standard steel or copper installation, so they can be run in longer straight sections without needing so many compensation elements.

Along with the pipes come fittings - elbows, tees, reducers, threaded transitions (internal and external), transitions to copper, and blanking caps. The system also includes manifolds for both underfloor and radiator heating, which distribute water from one main supply into several separately shut-off circuits. For example, a manifold with 4 circuits allows four separate branches to be connected from one riser pipe (for example four rooms or four radiator circuits), with each circuit having its own shut-off valve - useful when one room needs to be shut down for repairs without shutting down the whole system.

For this specific task - splitting the main supply into four separate circuits - the following manifold is commonly used in our range:

4-circuit manifold with valve, 15 x 15 x 15 x 15 - distributes the main supply into four independently shut-off circuits, exactly as in the diagram above - suitable for a combination of radiator and underfloor circuits in one flat or smaller house. Price from 41.69 EUR.

What HEPWORTH is actually used for

The first and most common application is the distribution of cold and hot domestic water in flats and family houses - what an ordinary person calls "plumbing". The second large group is heating: the supply and return to classic radiators, or piping to convectors. A third, increasingly common application is underfloor heating, where a special pipe with an oxygen barrier is usually used (not all HEPWORTH ranges have this barrier, so it needs to be checked when choosing a specific type), but the principle of joining and splitting circuits is identical to classic heating. A fourth area is industrial use - process water systems, low-pressure compressed air, or cooling water in facilities where resistance to corrosion is valued.

The common denominator of all these uses is that they involve water systems (not gas) with pressures and temperatures that plastic can safely handle. Plastic PPR systems are not commonly used for gas distribution - other, specifically certified systems and materials belong there.

Pressure and temperature classes - what PN10, PN16, PN20 mean

When choosing a specific type of pipe, you will encounter the designation PN followed by a number - for example PN10, PN16, or PN20. This number indicates the nominal pressure in bar that the pipe can safely withstand at a reference temperature (typically 20 °C) throughout its planned lifespan. At higher operating temperatures, such as commonly occur in a heating circuit, the actually permissible pressure decreases - this is a normal physical property of plastics, not a material defect. That is why higher pressure classes (PN16 or PN20) are recommended for heating, while PN10 is often sufficient for cold water distribution at low operating pressure.

Typical operating temperature of heating water in family houses ranges between 40 and 70 °C, with older high-temperature systems occasionally even higher. The HEPWORTH system in its standard version tolerates continuous operating temperatures up to approximately 70 °C, and briefly (for example in the event of a control failure or during hot water disinfection) also temperatures approaching 95 °C. This is exactly why, when designing a heating circuit, it is important to check that the chosen combination of pipe, pressure class, and temperature matches the actual operating conditions of the building - this is not just a formality, but insurance against premature wear of the material.

A simple rule applies in practical selection: for cold water distribution and low-pressure applications, PN10 is sufficient; for hot domestic water and classic heating, PN16 is recommended; and for industrial applications or situations with higher operating demands (for example long runs with a higher pressure drop), PN20 is chosen. There is no need to worry about "over-sizing" - a higher class is never a drawback, just a bit more expensive.

Methods of joining pipes and fittings

The basic and most common way of joining HEPWORTH pipes is butt fusion welding (welding using a welding machine with interchangeable heads according to diameter). The end of the pipe and the inside of the fitting are simultaneously heated on the welding head to a temperature of around 260 °C, then, once removed from the head, joined together and left to set for several seconds without moving. The result is a homogeneous, materially uniform joint that, when correctly made, is stronger than the pipe itself - this is a fundamental difference compared to mechanical joints, where there is always a sealing element (o-ring, Teflon tape) that can degrade over time.

For pipe diameters where manual butt fusion welding would be impractical, or where a dismountable joint is needed (for example a transition to an existing metal system, or a spot with an anticipated future modification), electrofusion fittings with a built-in resistance wire (welding with an electro-coupler) or mechanical compression fittings are used. A compression fitting is especially practical for plastic-to-metal transitions or when repairing older pipework, where a new plastic section needs to be connected to existing copper pipe without welding.

Compression fitting for copper pipe - 15x1-EK - a typical example of a mechanical joint when transitioning from a plastic HEPWORTH system to existing copper pipe, without any welding. Price from 2.51 EUR.

Filters are also part of almost every installation, protecting the whole system from mechanical impurities coming from the water mains - sand, rust from the public water supply, or fragments of seals can accumulate over time in fittings and reduce flow, or damage valves. That is why a sludge trap or cyclonic filter is commonly fitted on the main supply before the manifold.

Cyclonic sludge trap filter 4" - 1/2"F - we recommend fitting it on the main supply before the manifold, so mechanical impurities from an older water main do not damage the fittings and valves downstream. Price from 102.34 EUR.

After welding the whole section, a pressure test is essential before the pipework is covered in a wall, screed, or ceiling void - this is a step that, in practice, is unfortunately sometimes skipped under time pressure, but it is exactly here that a possible joint defect is revealed while it is still cheap and quick to fix. Once the pipework is covered, repairing a leak is many times more expensive and complicated.

When fixing pipework to a ceiling, wall, or into a chase, metal or plastic clips/clamps are used to hold the pipe in the required position while also allowing it slight longitudinal dilatation (for uncompensated sections). When machine-fixing a large number of pipes at once (for example during series installation in a new build), it is worth reaching for clips joined into a strip, which can be applied quickly by machine.

HS 45mm clips for machine pipe fixing, joined by wire into a strip - speed up installation when a large number of fixings are needed on site, practical for bulk installation of pipework in new builds. Price from 21.77 EUR.

Lifespan and comparison with other materials

With correct installation (welding temperature and time followed, sufficient compensation for linear expansion, protection from direct UV radiation for outdoor runs), the lifespan of plastic HEPWORTH pipework is commonly quoted at around 50 years - comparable to copper pipe and significantly longer than galvanised steel, which corrodes internally over time and whose real-world lifespan in practice commonly does not even reach half that figure (roughly 20 to 25 years, depending on water quality and the aggressiveness of the environment).

In terms of price, the plastic system is generally cheaper than copper pipe - this depends on current metal market prices, but roughly speaking you can expect savings on both material and labour, since butt fusion welding is faster and does not require an open flame (unlike soldering copper), which is an advantage especially when working in inhabited spaces or near flammable materials. On the other hand, you need to account for the higher thermal expansion of plastic, which must be correctly compensated for at the design stage - if this is forgotten, it can cause tiling to crack where the pipe crosses a wall, or a loud "clicking" sound in the pipework as it heats and cools.

Radiator connection and temperature control

At the end of every heating circuit, whether run in HEPWORTH or another pipe, there is finally a radiator or other heating element. This is exactly where it is worth investing in a quality thermostatic control valve, which allows the water flow into the radiator to be automatically limited once the set room temperature is reached - without it, a manifold system with four independent circuits loses part of its purpose, since each room should have the option of independent regulation.

Straight thermostatic radiator control valve, EK x 1/2" - fitted at the end of each radiator circuit from the manifold, allowing independent temperature control in each room. Price from 8.58 EUR.

What to watch out for when choosing and designing

The first common mistake is mixing components from different manufacturers without verifying the compatibility of size ranges and joining systems - even though the pipe and fitting may look similar on the outside, a small difference in diameter or wall thickness can result in a leaking or insufficiently strong weld. The second common mistake is underestimating linear expansion on long straight sections, especially with unreinforced pipe run, for example, along the surface of a basement or plant room wall. The third mistake is using the wrong pressure class for the given application - for example fitting PN10 pipe on a heating circuit with a higher operating temperature, where the actual pressure margin at operating temperature drops below a safe threshold.

A fourth, often underestimated factor is the quality of the water in the system itself - even though the pipework is made of durable plastic, mechanical impurities (sand, rust from the public mains, installation debris) can over time clog the narrower cross-sections of fittings and thermostatic control valves. That is why a sludge trap filter on the main supply is worthwhile even in a new build, not just in the renovation of an older house.

Summary - when to choose the HEPWORTH system

The HEPWORTH system is a good choice whenever you need reliable, affordable, long-lasting distribution of cold or hot water, classic radiator heating, or underfloor heating - especially in new builds and larger renovations, where the route, including compensation for linear expansion, can be designed in advance. For minor repairs or connecting to existing metal pipework, mechanical compression joints will do the job; for larger installations, investing in a proper welding machine pays off (or you can have the welding done by a professional installation company that has the equipment and experience).

Storage, handling, and protection from UV radiation

Even before installation itself, it is worth paying attention to how the pipes are stored on site. Polypropylene is sensitive to prolonged exposure to direct sunlight - ultraviolet radiation gradually degrades the surface layer of the material, which over time becomes brittle and loses its original mechanical properties. Pipes on a construction site should therefore not be left lying loose in the sun for weeks, but should be covered with a tarpaulin or stored in the shade, ideally in the manufacturer's original packaging. For outdoor runs (for example a short section between a boiler room in a separate building and the house), it is recommended to additionally protect the pipe - either with a suitable UV-resistant coating, or mechanically, for example by placing it inside a protective conduit or covering it with an insulating jacket that also serves a thermal insulation function.

When handling larger diameter pipes (from around 32 mm upwards), it is also important to bear in mind that plastic is more brittle at low temperatures (below freezing) and more prone to cracking from a careless impact or fall - so in winter it is recommended to let the pipes acclimatise in a warmer environment for at least a few hours before cutting and welding begins. This is a small detail that an experienced installer takes for granted, but is easy to forget in DIY installation, and the result can be microcracks that only show up as a leak months into operation.

DIY installation versus a professional installation company

The HEPWORTH system is fairly friendly even for a competent DIY enthusiast with the right tools - a welding machine with heads for common diameters (20, 25, 32 mm) can be bought or hired for a reasonable price, and the welding procedure itself can be mastered after a few practice welds on offcuts. Nevertheless, for larger installations (a whole heating system in a family house, several radiator or underfloor circuits), we recommend entrusting the installation to a professional company, for two reasons. First, a mistake in one incorrectly made weld only shows up after some time in a covered installation (in a wall, in screed), and fixing it is far more expensive than the original installation. Second, correctly designing compensation for linear expansion and sizing the diameters of individual circuits requires at least a basic hydraulic calculation, which an experienced company does routinely, whereas in DIY installation it is often done "by eye".

If you nevertheless decide on a DIY installation, we recommend at least having the final pressure test carried out under the supervision of an expert, or checking the result with an installation company, which can use experience to assess whether a pressure drop is within normal limits or indicates a microscopic leak at one of the joints.

Frequently Asked Questions

Can HEPWORTH also be used for gas distribution?

No. The HEPWORTH system is intended for water distribution - cold water, hot domestic water, and heating water. Other, specifically certified materials and systems are used for gas distribution; plastic PPR pipe is not intended for this purpose and does not have the necessary approvals for it.

Do I always have to weld the pipe during installation, or is there a dismountable solution too?

Classic butt fusion welding creates a permanent, non-dismountable homogeneous joint. If you need a dismountable connection (for example for servicing or a transition to metal pipe), you would use a mechanical compression fitting or threaded transitions, which can be taken apart again if needed.

What is the difference between PN10, PN16, and PN20?

The number after the PN abbreviation indicates the nominal pressure in bar that the pipe can safely withstand at a reference temperature of 20 °C. At higher operating temperatures (typical of heating), the actually permissible pressure drops, which is why higher classes (PN16 or PN20) are recommended for heating circuits, while PN10 is often sufficient for low-pressure cold water distribution.

How long does HEPWORTH pipework last with correct installation?

If the correct welding procedure is followed and linear expansion is adequately compensated for, the lifespan is quoted at around 50 years, which is comparable to copper pipe and significantly more than older galvanised steel, which corrodes internally over time.

Is a sludge trap filter needed even in a new build where all the pipework is new?

Yes, we recommend it. Mechanical impurities can get into the system from the public water mains or directly during construction (installation debris, sand). The filter protects fittings, valves, and thermostatic heads from premature wear or reduced flow.

Can the HEPWORTH system also be used for underfloor heating?

Yes, pipe versions with an oxygen barrier are used for underfloor heating, which prevents oxygen from penetrating into the heating water and thereby reduces the risk of corrosion of the metal parts of the system (boiler, pump, fittings). The principle of splitting circuits via a manifold is the same as with classic radiator heating.

Have a question on this topic?

Can't decide, or dealing with a specific situation in your household? Write to us - we're happy to help.