How to choose the right HEPWORTH pipe for heating
How to choose the right HEPWORTH pipe for heating – complete guide
Choosing the right pipe for heating is not just a matter of price or material availability in the store. It is a decision that affects the reliability and lifespan of your heating system for decades to come. Multilayer plastic pipe HEPWORTH has gained a solid position on the Slovak and Czech markets in recent years – and for good reasons. In this article, we will go through everything you need to know before deciding which pipe to buy, which diameter to choose, and in what form to have it on the construction site.
If this is your first time here and you are still getting familiar with the terminology, I recommend reading the article Difference between HEPWORTH and HEP2O pipes for heating – it will help you navigate the product range. But let's start from the beginning.
What is HEPWORTH pipe and why it is suitable for heating
HEPWORTH is a British brand with a long history in the production of plastic pipe systems. HEPWORTH heating pipe is multilayered – it consists of a PE-RT (temperature-resistant polyethylene) layer, reinforced with an aluminum layer, and again covered with a PE-RT sheath. This construction is not random: each layer has its own function.
The central aluminum layer performs three key roles. First, it prevents oxygen diffusion into the water – which is crucial for heating, as oxygen accelerates the corrosion of iron parts (circulation pumps, distributors, boiler). Second, it stabilizes the dimensions of the pipe during temperature changes – plastic pipes expand when heated, and aluminum significantly dampens this effect. Third, the pipe retains its shape after bending – which is a huge advantage during installation compared to purely plastic pipes.
The operating parameters of HEPWORTH heating pipes are generally stated as PN10 at 95 °C, which in practice means they are suitable for most standard heating systems with gas, pellet, or heat pump boilers. For condensing boilers, where water temperature does not exceed 75–80 °C, these pipes have a significant reserve.
Which diameter of HEPWORTH pipe to choose: 15, 22 or 28 mm?
This is the number one question customers come with. And at the same time, it is a question for which there is no universal answer without knowing the specific project. Despite this, there are clear rules that most plumbers follow.
15 mm pipe – for radiator connections and floor heating
HEPWORTH heating pipe 15 mm is the most common diameter in apartment and family homes. It is mainly used for connections to individual radiators, in floor heating systems (where we more often encounter a 16 mm diameter in the form of flexible PE-RT without an aluminum layer), and for shorter runs in smaller spaces.
In practice, it is considered that for a radiator connection in a standard living room (up to 15–20 m²) a 15 mm diameter is sufficient without any problems. The pressure loss on such a connection is negligible, the flow is sufficient, and the installation is simple – the pipe is flexible, bends well, and easily reaches the radiator valve even in areas with limited space.
A typical project where you see 15 mm in action: renovation of an apartment in a panel building, where new horizontal runs are made behind drywall or in a floor channel. Each radiator gets its own connection from the distributor (so-called star layout), with all connections made from 15 mm pipe.
22 mm pipe – main runs in family homes
HEPWORTH heating pipe 22 mm is the standard for main distribution branches in family homes and smaller commercial buildings. If the boiler has a power of up to 20–25 kW and supplies 8–12 radiators, the main pipe from the boiler to the distributors will typically be 22 mm. The pressure loss is low, the flow is sufficient, and the sizing is proven by years of practice in such situations.
Twenty-two millimeters is also the diameter that appears in mixed systems: the main branch runs in 22 mm, from which it branches into 15 mm to individual rooms or radiators. Such a layout is hydraulically well balanced and does not require complicated regulatory interventions.
28 mm pipe – larger systems and boiler connections
HEPWORTH heating pipe 28 mm is used in cases where a high flow is required – connection of a boiler with higher power (over 25–30 kW), main horizontal runs in multi-storey buildings, or if the system is oversized for future expansion (for example, adding another heating zone or a solar collector to the system). In family homes, 28 mm is encountered more rarely, but in larger homes, agricultural buildings, or industrial heating infrastructure, it is standard.
More detailed hydraulic calculations and specific flow tables can be found in the article What diameter of heating pipe do I need: 15, 22 or 28 mm – there these values are processed into a practical table.
Coils vs. straight pipes – which pipe shape is better for you?
After selecting the diameter, the next important choice is whether to use coiled or straight pipes. Both forms have their advantages and limitations, and the choice depends on the nature of your order.
HEPWORTH coiled pipes
Coiled pipes (spools) are typically supplied in lengths of 25, 50 or 100 meters. The main advantage is flexibility during installation – you can easily run long runs without joints, bend them manually or with a bender, and overall, working with them is faster when the routing is less predictable (for example, during renovations, where you have to avoid existing installations or structural elements).
The disadvantage of a coil is that the pipe has a natural tendency to twist back after unrolling – which can be annoying for long straight sections. Experienced installers can easily handle this, but for less experienced DIYers it can be frustrating. You also need to consider that a coil in a larger diameter (e.g. 28 mm) is heavy and unrolling it requires space or a special rod for unwinding.
HEPWORTH straight pipes
Straight pipes are supplied in standard lengths of 3 or 5 meters. They are straight, stiffer and ideal where you need precise, straight routing – for example in machine rooms, technical rooms, or where the piping is run on consoles and installation systems along the wall or ceiling.
HEPWORTH heating pipes in straight lengths 15 mm and HEPWORTH heating pipes in straight lengths 22 mm are standard products for these situations. Straight pipes can be measured, cut and connected with fittings very precisely – and the result is visually cleaner, suitable for example in a technical room, where the customer wants a "well done" layout.
Practical tip from practice: if you are renovating an apartment or a family house with a complicated routing, choose coils – you will save time and the number of joints. If you are building a new house with a machine room or a large recovery/heat system with long straight sections, straight pipes are usually more practical and the result is much clearer. More on this topic can be found in the article HEPWORTH coiled pipes vs. straight pipes – what to choose.
Technical parameters to look at when choosing
I don't want to just repeat what is written on the product label – rather, let's look at what these parameters really mean when choosing.
Pressure and temperature classes
Most HEPWORTH heating pipes are certified for temperature classes up to 95 °C and operating pressure PN10 (10 bar). This is more than sufficient for standard heating – most boilers operate at temperatures of 60–80 °C and pressures of 1.5–2.5 bar. The maximum operating pressure in a standard installation does not exceed 3–4 bar.
However, be careful in specific situations: if the system is connected to district heating (CZT/central heating), where pressures can reach 6–8 bar, you need to verify this with the supplier and possibly dimension accordingly.
Diffusion tightness to oxygen
The aluminium layer serves as a diffusion barrier – oxygen does not pass through it. This is a legal requirement for heating systems with closed metal components (pumps, steel heat exchangers in boilers, cast iron radiators). If the pipe did not have this barrier, oxygen diffusing through the wall would cause corrosion, scale formation and ultimately pump failures and a shortened lifespan of the entire system.
HEPWORTH multilayer pipe meets the requirement for oxygen diffusion tightness according to EN ISO 15875, which is also why boiler installers recommend it without reservations.
Coefficient of thermal expansion
Multi-layer PE-RT/Al/PE-RT pipe has a coefficient of thermal expansion of around 0.026 mm/m·K – this is significantly less than pure plastic pipe (PE, PEX), where values are 0.15–0.20 mm/m·K. In practice, this means that with a temperature change of 50 °C, a 10-meter section of HEPWORTH pipe will extend by about 13 mm, while a pure plastic pipe would extend by 75–100 mm. This difference has a direct impact on the way of fixing and compensating for expansion – with HEPWORTH the requirements are much lower and the installation is simpler.
How to think about planning the layout step by step
Experience from practice shows that most errors in pipe selection do not come from lack of product knowledge, but from the fact that the installer (or DIYer) does not make a basic layout drawing before starting the work. In fact, it is enough to make a very simple schematic sketch on paper.
When planning the layout, ask yourself these questions:
- What is the boiler output? From this, the diameter of the main pipe is derived. A rough rule of thumb: 22 mm is sufficient for up to 15 kW, for more than 25 kW consider 28 mm.
- How many radiators and what is their approximate thermal load? A radiator with an output of up to 1.5 kW can be easily supplied from a 15 mm connection. A larger radiator (e.g. a bathroom dryer or a large panel radiator over 2 kW) may require 22 mm.
- How long are the individual branches? The longer the branch, the higher the pressure loss – and the larger the diameter may be needed. A branch longer than 15 meters in 15 mm must always be calculated, not just estimated.
- Where will the crossings through structures (walls, ceilings) be? Here you need to think about protective sleeves and expansion.
- Is it a closed system? In a closed system, diffusion tightness must be ensured – and HEPWORTH meets this condition.
What to consider when purchasing – practical tips before ordering
Once you know the diameter and form you want, it's time to calculate the quantity. This is where being thorough really pays off – unnecessary leftovers are a waste, and a shortage of material halfway through the job will raise your blood pressure.
How to accurately estimate pipe consumption
The basis is a sketch of the route to scale – even a quick, hand-drawn one on paper. Measure each section and add them up. Then add a 10–15 % reserve for bends, cutting errors and unforeseen route changes. For a larger project (an entire family house), a 15 % reserve is realistic, while for a smaller job (one apartment), 10 % is sufficient.
Don't forget that when buying coils, you purchase the whole roll – if you need 48 meters and the coil is 50 m, you buy one coil and 2 meters will remain. That's fine. But if you need 52 meters and the coil is 50 m, you have to buy two coils (100 m in total) – which can be a source of surprise in the price.
Elbows, clamps and fittings
Pipe without fittings is just a rod. In the HEPWORTH heating system, either crimping or threaded installation is used. Crimped fittings are faster and more reliable for permanent piping – the connection is created by hydraulic crimping and, when properly done, is permanently watertight. Threaded (press-fit) fittings are suitable where you need removable connections – for example, when connecting to valve blocks or at inspection points.
Always check the compatibility of fittings with the pipe diameter and type. Most suppliers sell HEPWORTH fittings as a separate product line – and mixing systems from different manufacturers without verifying compatibility is a source of future problems.
Thermal insulation of pipe
In a family house, heating lines are typically routed either in walls/floor (where insulation is not mandatory, but recommended), or in the technical room and non-heated areas (where insulation is essential). Without insulation on pipes in non-heated areas, you will lose dozens of euros annually on thermal losses in places where you don't need it – and this adds up over 20 years.
For HEPWORTH heating pipes, standard sleeve insulations made of PE foam or mineral wool with a wall thickness of 13–25 mm are used, depending on the temperature difference and pipe location. In the boiler room, we usually choose thicker insulation (20–25 mm), while 13 mm is sufficient for routes inside the building.
Typical project scenarios from practice
Let's look at a few specific situations that we commonly encounter in practice and how we would solve the pipe selection for each of them.
Scenario 1: Apartment renovation in a panel building
Apartment 3+1, area 72 m², original steel pipes behind drywall are going to the bin. We plan a star layout from the hallway (where the manifold will be) to six radiators. The boiler remains the original gas one, power 14 kW. Maximum heating water temperature 70 °C.
Solution: Main connection from the boiler to the manifold: 22 mm, length approx. 4 m. All connections from the manifold to the radiators: 15 mm, average connection length 7–10 m. Total consumption: approx. 5 m × 22 mm + 6 × 9 m = 5 + 54 = 59 m × 15 mm. We buy 1× coil 22 mm (25 m, the remainder remains in stock for future small jobs) and 1× coil 15 mm 50 m + 1× coil 15 mm (or 2× 50 m coils). Reserve approx. 12 %.
Scenario 2: New family house construction, 2 floors
House 180 m², 2 floors, condensing boiler 20 kW, 12 radiators + bathroom heater, boiler room in the basement. Pipelines are planned in drywall and partially in the floor structure.
Solution: Rising pipe from the basement to the ground floor and to the upper floor: 22 mm (or 28 mm if the route is long or system expansion with solar is planned). Horizontal pipelines on each floor: 22 mm. Connections to radiators: 15 mm. Pipelines in the boiler room (from the boiler to the expansion tank, safety system, etc.): 28 mm for boiler connection, 22 mm for internal connections. In the boiler room, it is recommended to use pipe in straight lengths for a clean and neat appearance.
Scenario 3: Agricultural hall with space heating
Hall 600 m², heating via large radiators or air heating units, pellet boiler 60 kW. Pipelines are routed above ground on consoles under the roof.
Solution: Main pipelines from the boiler: 28 mm. Secondary pipelines to units: 22 mm. Unit connections: 22 or 15 mm depending on the unit's power. Pipe in straight lengths is more practical here for long straight sections on the consoles. Insulation is essential – at least 25 mm sleeves on all routes.
Safety and standards – what the pipe must meet
When selecting heating pipe for a family house or apartment building in Slovakia, the following standards and requirements apply:
- STN EN ISO 15875 (equivalent EN ISO 15875) – sets requirements for plastic pipe systems for heating, including diffusion tightness.
- STN EN 1264 – standard for floor heating, which sets requirements for pipe materials in floor heating systems.
- Boiler manufacturer guidelines – most boiler manufacturers (Vaillant, Viessmann, Buderus, etc.) specify which pipe materials are accepted for connection to their boilers. Multilayer PE-RT/Al/PE-RT pipe is generally accepted, but always verify this in the technical documentation of the specific boiler.
- Local building regulations – for larger installations (apartment buildings, commercial buildings), professional installation and inspection may be required. For a family house in a standard scale, most installations do not have special requirements for certification.
For installation and step-by-step instructions, I recommend reading the article Installation of HEPWORTH heating pipe step by step, where these steps are described in detail, including crimping procedures and leak testing.
Lifespan and maintenance – what to realistically expect
Multilayer pipe systems PE-RT/Al/PE-RT are designed for a lifespan of 50 years or more when installed and operated correctly. This is not a marketing figure – it is derived from accelerated testing required by ISO standards for these systems. In practice, the lifespan depends on the quality of installation, operating parameters (not exceeding maximum temperatures and pressures), and the quality of water in the system.
The main rule for operation is to keep the pH of the water in the system between 7–9 and the hardness up to 200 mg/l CaCO₃. Water that is too soft (low hardness) can be aggressive to certain materials, while water that is too hard causes limescale deposits. More on this topic can be found in the article HEPWORTH heating pipe – maintenance and lifespan.
As for routine operational checks: multilayer pipe requires practically no maintenance. Connections made with properly crimped fittings are lifetime maintenance-free. It is advisable to check the pressure in the system once a year (after filling and air removal, it should remain stable) and visually inspect the visible sections in the mechanical room.
Most frequently asked questions (FAQ)
Can I use HEPWORTH heating pipe for cold or potable water distribution?
HEPWORTH pipe marked as "for heating" (Heating) is not primarily certified for potable water distribution. For cold and hot utility water distribution, there is a separate range called HEP2O or other certified systems for potable water. Some universal multilayer systems are certified for both purposes – but always verify this in the technical data sheet of the specific product. More on this topic in the article Using HEP2O pipe for heating and water distribution in one system.
What is the difference between HEPWORTH and HEP2O?
HEPWORTH is a brand and product line of the manufacturer, while HEP2O is a specific sub-range of systems from the same manufacturer, primarily intended for water distribution (cold/hot utility water). HEPWORTH heating pipe is optimized for the temperature and pressure parameters of heating systems and is certified according to the relevant standards. Detailed differences are covered in the article Difference between HEPWORTH and HEP2O pipe for heating.
Can I bend HEPWORTH heating pipe by hand without a bender?
Yes, multilayer pipe can be bent manually – the aluminum layer allows for bending and the pipe retains its shape. The minimum bending radius for 15 mm is usually 5× the outer diameter (about 75 mm), for 22 mm approximately 110 mm, and for 28 mm approximately 140 mm. Bending with a smaller radius may cause deformation or breakage of the aluminum layer. For precise and clean bends, especially on visible runs, it is recommended to use a manual or hydraulic bender suitable for the pipe diameter.
Is HEPWORTH pipe suitable for heat pumps?
Yes, multilayer PE-RT/Al/PE-RT pipe is fully suitable for systems with heat pumps, including low-temperature systems (floor heating, fancoils). Heat pumps typically operate at water temperatures of 35–55 °C, which is significantly below the maximum operating temperature of HEPWORTH pipe. However, correct installation and ensuring diffusion tightness are important, which this pipe is designed for.
What if I need to connect HEPWORTH pipe to an existing copper piping system?
Connecting plastic multilayer pipe to copper is a common situation during renovations. Transition fittings are used – typically crimp or threaded (external/internal thread G1/2" or G3/4") – which fit one side to the multilayer pipe and connect to the copper pipe on the other side either by soldering or a crimp fitting for copper. This transition does not require any special permit or restriction – it is standard practice.
Where to buy HEPWORTH heating pipe – how to verify that it is an original product?
Always purchase from certified and verified distributors. Original HEPWORTH pipe has the technical parameters (outer diameter, wall thickness, standard, pressure class, production date) embossed on the surface. When buying online, make sure the seller lists the full technical parameters and is able to provide conformity certificates. All pipes in the category heating pipes on atria.sk are original products with the appropriate documentation.
Conclusion – summary of key decision criteria
Selecting the right HEPWORTH heating pipe can be summarized into a few basic steps. First, determine the performance of your system and the nature of the project – this will answer the question of the diameter. For standard apartment and family homes, the combination of 22 mm for main runs and 15 mm for radiator connections is a proven and hydraulically balanced solution. Larger and more powerful systems may require 28 mm for the primary circuit.
Then decide whether to use reels or straight lengths – in renovations with complex routing, reels are usually more convenient, while in new builds with clear straight sections, straight lengths give a cleaner and more professional result. Do not forget about expansion, insulation, correct selection of fittings, and pressure testing after installation.
And if you are unsure about anything – read the relevant professional articles in the Knowledge Center, or consult with a sales representative. A well-planned heating distribution system is worth addressing thoroughly before the first cut into the pipe, not after.
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.