HEPWORTH for Underfloor Heating
HEPWORTH for Underfloor Heating
Underfloor heating is today one of the most sought-after ways of heating family homes and flats - it provides even heat, a lower heating water operating temperature, and a pleasant feeling of warmth right from the feet up. What gets talked about less is what system of pipework and connecting components is used between the heat source (boiler, heat pump) and the underfloor loops themselves. That's exactly where the HEPWORTH system comes in - a proven plastic pipework system that has established itself in installation companies' practice as a reliable, affordable alternative to classic copper pipework. In this article we look practically at exactly where HEPWORTH is used in underfloor heating, what components you'll need, what to watch out for during installation, and what real-world experience looks like.
Why HEPWORTH suits underfloor heating so well
Underfloor heating works on a different principle than classic radiator pipework. The water in the underfloor loops circulates at a lower temperature (usually 30 to 45 °C versus 55 to 70 °C for radiators), but the pipework between the boiler and the manifold has to handle higher flow rates, since heat is released over a larger area gradually through several separate circuits. This places particular demands on the distribution pipework before the manifold and after the return collector - and it's exactly here that the HEPWORTH system is most often used in practice.
HEPWORTH is a system of moulded plastic pipes and connecting elements (elbows, tees, reducers, threaded transitions) joined by welding or mechanical screwing, depending on the specific joint type. Its main advantages in the context of underfloor heating include:
- Corrosion resistance - unlike steel pipework, the inside of the pipe doesn't rust over time, which is especially important for closed underfloor heating circuits, where the water isn't exchanged for years.
- Lower weight and easier handling - when installing in a utility room or a service shaft, the lighter pipe is quicker to work with than copper, saving both installation time and labour costs.
- Good affordability of connecting parts - HEPWORTH elbows, tees and reducers tend to be cheaper than their copper or brass equivalents of the same diameter.
- Compatibility with common fittings - threaded transitions (for example 1/2" or 3/4") make it easy to connect manifolds, filters and radiator valves without needing special tools.
It's important to say that in the vast majority of installations, HEPWORTH isn't used directly as the material for the underfloor loops themselves cast into the screed (specialised PE-RT system pipe or multilayer pipe with an oxygen barrier is used for that) - its place is in the pipework between the boiler room/utility room and the manifold, or in the connecting sections between several manifolds on a given floor. It's exactly this part of the installation that, in terms of pressure, temperature and mechanical stress, is a typical "plumbing" task, which HEPWORTH as a plastic pressure system is built for.
Basic connection diagram
To make it clear exactly where in an underfloor heating system HEPWORTH components come into play, let's look at a simplified diagram of the heating water flow from the boiler to the underfloor loops and back.
As the diagram shows, HEPWORTH components (distribution pipework, elbows, the compression fitting connecting the manifold) are found at two key points: on the supply branch from the boiler to the manifold, and on the return branch from the return collector back to the boiler. The underfloor loops themselves (right side of the diagram) remain made from system pipe intended directly for the screed - HEPWORTH doesn't replace that.
Which HEPWORTH components you'll most often need for underfloor heating
In a typical installation for a family house with two to four heating circuits, a handful of component types keep coming up in practice. Rather than a general list, it's more useful to go through them with specific, actually available products you can factor into a budget already.
1. Sediment filter before the manifold
The first recommended component on the supply branch is a sediment (cyclonic) filter. Its job is to capture mechanical debris, sludge and deposits before they reach the manifold and, further on, the thin underfloor loops, where they could cause partial clogging and reduced flow in a specific circuit. With underfloor heating, this component matters even more, since the loop diameter is significantly smaller than radiator pipework and is more sensitive to any debris in the system.
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Cyclonic sediment filter 4" - 1/2"F - fitted directly before the manifold on the supply branch, captures debris via the cyclonic principle with no need for a cleaning cartridge, reducing the risk of individual underfloor circuits clogging. From €102.34. |
2. Heating circuit manifold
The heart of the whole underfloor system is the manifold, which distributes water from one supply pipe into the individual circuits and then collects them again on the return. It's here, when connecting the manifold to the main pipework, that HEPWORTH threaded transitions come into play most often - you need a reliable, sealed transition from plastic pipe to the manifold's threaded connection.
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4-circuit manifold with valve, 15 x 15 x 15 x 15 - suitable for smaller installations with up to 4 separate underfloor circuits, each with its own shut-off valve for adjusting/isolating a circuit without touching the rest of the system. From €41.69. |
3. Compression fitting for connecting to copper or plastic pipe
If HEPWORTH pipework is combined with existing copper sections in the pipework (common in renovations, where underfloor heating is added to a house with original copper pipework to radiators), a reliable mechanical joint is needed. A compression fitting allows this connection without soldering, which is practical especially for repairs or later modifications to the pipework.
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Compression fitting - for copper pipe - 15x1-EK - a detachable mechanical joint suitable for combining HEPWORTH pipework with existing copper pipe, with no need to solder on site. From €2.51. |
4. Mounting and running the pipework
The distribution pipework before the manifold and after the return collector needs to be securely mounted to the building structure - to a wall, ceiling, or into an installation partition. With several parallel pipes (the supply and return branch running side by side), installers in practice most often prefer machine-assisted mounting with clips joined into a strip, which can be applied quickly even with a large number of mounting points on one section.
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HS clips 45mm for machine-assisted pipe mounting, joined with wire into a strip - speed up installation where there are many mounting points side by side, a practical solution for running the supply and return branch to the manifold in parallel. From €21.77. |
5. Radiator valve for combined systems
In many houses, underfloor heating is combined with classic radiators (typically a heated towel rail in the bathroom alongside underfloor heating in the other rooms). In that case, a separate circuit with a thermostatic valve for the radiator is also connected to the same HEPWORTH distribution branch.
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Thermostatic radiator valve - straight, EK x 1/2" - suitable for combined systems, where alongside the underfloor circuits the same system also includes a separate radiator (typically in the bathroom). From €8.58. |
Comparing the approximate cost of basic components
To give you a rough idea of the budget for connecting materials when installing one manifold with four circuits, let's look at the approximate prices of the components mentioned above in a chart comparison.
The chart shows that the biggest single item in this group is the sediment filter (€102.34), which is usually only bought once for the whole system, while cheaper connecting parts like the compression fitting (€2.51/pc) or the radiator valve (€8.58/pc) are bought in quantities matching the actual number of joints and circuits in the given installation. The manifold (€41.69) is a mid-sized item, whose price grows with the number of circuits (more outlets, more valves in the manifold body).
Step-by-step installation procedure
Installing HEPWORTH pipework to an underfloor manifold has its own logical sequence, worth following even for smaller installations. The following diagram captures the six main steps of a typical installation.
Once the mechanical installation is complete, a sixth, equally important step follows - a pressure test of the whole system before the underfloor loops are cast in screed. This step is deliberately left out of the installation-steps diagram above, since it deserves its own attention in the next section.
Pressure test and casting into the screed
Before the underfloor loops are cast in screed, it's essential to pressure-test the whole system, including the sections with HEPWORTH components. In practice, the test pressure is most often about 1.5 to 2 times the system's operating pressure (typically around 4 to 6 bar, depending on the specific project and the designer's recommendation), held for at least 24 hours with no pressure drop. All joints need to be checked - including the compression fittings and manifold transitions - both visually and by a leak-tightness test.
A common mistake seen in practice is rushing to cast the screed before the pressure test is fully complete, or right after it without enough of a gap to check for any microscopic leak. If a problem shows up only after casting, the repair is significantly more complicated and expensive, since the already-finished floor has to be partly taken apart. That's why in practice it's recommended to keep the system under pressure during the casting itself and for the following few days while the screed sets - this way any leak is caught before it's too late.
The most common mistakes when combining HEPWORTH and underfloor heating
From the experience of installation companies that regularly work with atria.sk, a handful of typical mistakes keep recurring:
- Skipping the sediment filter - saving a few dozen euros during installation can, within a few years, show up as reduced flow in one or more circuits due to deposits, requiring intervention in an already-finished floor or at least a laborious system flush.
- An undersized manifold - choosing a manifold with fewer circuits than the design actually requires, or without shut-off valves on individual circuits, which later makes servicing and flow adjustment harder.
- Insufficient pipe mounting - without regular machine mounting, the pipe sags, which over longer sections increases the risk of joint leaks over the years.
- Combining incompatible materials without a proper transition - directly connecting HEPWORTH pipe to copper pipework without a suitable compression fitting or transition piece, leading to leaks or accelerated corrosion at the point of contact between different materials.
- Underestimating the pressure test - as noted above, shortening or skipping an adequate pressure test before casting the screed is among the most expensive mistakes that can be made in an underfloor heating installation.
Comparing HEPWORTH with alternative pipework solutions
When deciding what material to use for the pipework between the boiler room and the underfloor heating manifold, in practice three main options are most often compared - classic copper, the HEPWORTH plastic system, and multilayer PE-RT/aluminium pipe. The following overview summarises the main differences installers and clients commonly encounter.
The table reflects a practically proven model commonly used in the field: HEPWORTH as the material for rigid, straight pipework between the boiler room and the manifold (where bending into complex curves directly in the screed isn't required), while the underfloor loops themselves are made from flexible PE-RT or Al-PE-RT pipe, which can be run according to a precise laying plan without a lot of fittings. Copper is on the decline mainly because of more demanding and expensive soldered installation, though it's still commonly found in older installations or when combined with existing radiator pipework - and it's exactly here, as described above, that a compression fitting comes into play for reliably connecting to the HEPWORTH part of the system.
Design principles for the manifold and number of circuits
When planning the manifold, it's important to think in advance about how many separate underfloor circuits the system will need - expanding later after the screed is cast is practically impossible without disturbing the finished floor. As a rough guide, one underfloor heating circuit covers an area of approximately 15 to 20 m², depending on the pipe spacing and the room's heat loss. For a typical family house with a living area of around 120 to 150 m², this works out to a need for 6 to 10 circuits, meaning either one larger manifold, or (more often, and practically more advantageous) two smaller 4-circuit manifolds placed closer to the individual zones of the house - for example one for the ground floor and one for the upper floor.
The manifold mentioned earlier in this article, the 4-circuit one with valve (15x15x15x15), is a typical example of a modular solution exactly suited to this kind of zone division - instead of one large manifold for the whole house, two or more smaller ones are used, each closer to the zone it serves, which also shortens the individual loops and improves control.
Servicing and maintaining pipework with HEPWORTH components
After the underfloor loops are cast in screed, the pipework between the boiler and the manifold generally needs only minimal maintenance, since the HEPWORTH sections are usually run visibly (in the utility room, a service shaft, or a suspended ceiling) and aren't cast directly into the structure. This is a big advantage for future servicing compared with a possible leak directly in the underfloor loops - a fault in visible pipework can be found and fixed without breaking up the floor.
Recommended regular maintenance includes:
- A visual check of the joints (especially the compression fitting and threaded transitions) once a year, ideally before the heating season.
- Checking, and if necessary cleaning, the sediment filter before the manifold - the frequency depends on water quality and the system's condition, roughly once every one to two years.
- Checking that the manifold's shut-off valves work properly - they should close and open smoothly without sticking, which can be verified with a simple turn once a year.
- For combined systems with a radiator (for example a bathroom towel rail), also checking that the thermostatic valve responds correctly to a setting change.
Frequently asked questions
Can HEPWORTH be used directly as the pipe cast into the underfloor screed?
In practice, this isn't done. Specialised system pipe (PE-RT or multilayer with an oxygen barrier) is used for the underfloor loops themselves cast into the screed - it's certified for long-term stress in a closed, inaccessible environment and has the flexibility needed for laying into spirals. HEPWORTH has its place in the pipework before the manifold and after the return collector, i.e. in the visible, accessible sections of the installation.
Can HEPWORTH be combined with existing copper pipework in an older house?
Yes, this is a common situation, especially in renovations where underfloor heating is added to original copper radiator pipework. A compression fitting for copper pipe (for example size 15x1) is used for the connection, creating a detachable, mechanically reliable joint with no need to solder on site.
How many circuits can one manifold handle, and when do I need more than one manifold?
Commonly available manifolds have from 2 to 12 outlets. For smaller installations, or when zoning a house (for example the ground floor and upper floor separately), it's often worth using several smaller manifolds in practice, for example two 4-circuit ones, instead of one large one - this shortens the individual loops and simplifies controlling the individual zones.
Does there always need to be a sediment filter before the manifold?
It isn't a legal requirement, but it's clearly recommended in practice, especially for underfloor heating, where the loop diameter is small and sensitivity to mechanical debris is higher than for radiator pipework. The cost of the filter usually pays for itself over the years by avoiding a service call-out for a clogged circuit, which would otherwise require flushing or, in the worse case, work on the floor.
How long should the pressure test last before casting the screed?
At least 24 hours with no pressure drop is recommended, at a pressure of roughly 1.5 to 2 times the system's operating pressure. For larger or more complex installations, it's a good idea to keep the system under pressure during the screed casting itself and for the following few days, so any leak is caught as early as possible, while the repair is still simple.
Can a damaged section of HEPWORTH pipework be easily repaired?
Since HEPWORTH pipework before the manifold and after the return collector is typically run visibly (utility room, service shaft, suspended ceiling), any repair is considerably simpler than a fault directly in the cast underfloor loops. The damaged section can be taken apart at the nearest joint (for example a compression fitting) and replaced with a new part with no need to break up the floor.
Related topics
- What is the HEPWORTH system and what is it used for
- How to choose the right HEPWORTH components
- Installing the HEPWORTH pipe system
- Most common mistakes when installing HEPWORTH
- Joining and sealing HEPWORTH pipework
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