Frequently Asked Questions About the HEPWORTH System

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The HEPWORTH system is one of the pipework solutions our customers ask about most often - for several reasons at once. It combines both metal and plastic elements, can be used for heating water distribution as well as for connecting radiators or underfloor heating, and that's exactly why choosing components raises so many questions. In our advice service and in the product discussions we see dozens of similar queries again and again - from what pipe diameter to choose, through the method of joining, to what to do when air or debris from the mains water supply shows up in the system. In this article we've collected the most frequent questions we get from installation companies and everyday DIYers, and we answer them practically, without unnecessary theory - the way we'd answer right there in the shop.

If you're dealing with the HEPWORTH system for the first time, we recommend first going through the basic overview in the article What is the HEPWORTH system and what is it used for - there we explain the principle and typical uses. This article, by contrast, takes things most people already know and addresses specific situations and decisions where people most often hesitate or make mistakes.

Why the HEPWORTH system generates so many questions specifically around choosing components

Unlike a simple boiler, where the customer basically chooses one product, a HEPWORTH system is always an assembly - pipe, connecting fittings, mounting, filtration, manifolds and valves. A mistake in one of these links shows up in the whole system, often only after years of operation (a leak, noise in the pipework, uneven heating of individual rooms). That's why it's worth paying attention even to seemingly small details, like the type of compression fitting or the spacing between clips.

What pipe diameter is right for my case?

This is by far the most common question we deal with. The answer depends on how much water (and therefore heat) needs to flow through that particular section. In practice, with the HEPWORTH system we most often encounter four basic bore sizes - 15, 20, 25 and 32 mm - and each has its typical use:

15 mm - connecting a single radiator or a single underfloor heating circuit. This is the best-selling size, found for example with the 15x1-EK compression fitting or with a 15x15x15x15 manifold connection.
20 mm - can supply two to three smaller circuits at once, or a longer riser pipe in a flat.
25 mm - a typical main riser in a family house, handles four to six circuits.
32 mm - the main feed from the boiler to the manifold in larger houses with eight or more circuits.

A practical rule we recommend to both installation companies and DIYers: never scrimp on the diameter of the main feed. Sizing up by one bore usually costs only a few euros extra across the whole project, while undersizing shows up as noise in the pipework and insufficient output during the coldest frost - and that's hard to fix, practically only by replacing the pipe section.

Diagram: recommended pipe diameter by number of circuits

How do I choose the right manifold?

The second most common question concerns manifolds. The manifold is the "heart" of the whole pipework - it splits one main feed into several separate circuits that can also be individually regulated or shut off. When choosing, ask yourself one simple question: how many separate branches (radiators or underfloor loops) do I actually need to connect now, and how many are likely to be added in the future (for example when finishing an attic)?

A common and proven option for a smaller family house or larger flat is a four-circuit manifold with valves, for example in a 15x15x15x15 configuration - i.e. a main inlet and four outlets at 15 mm bore, each with its own shut-off valve. This lets you close or throttle one circuit (for example during a bathroom renovation) without having to shut down the whole system.

4-circuit manifold with valve, 15x15x15x15

4-circuit with valve, 15 x 15 x 15 x 15 - a typical manifold for a smaller family house or flat, with four independently shut-off circuits, exactly the type our customers ask about most often. From €41.69.

If you need more circuits, the solution isn't to look for a "bigger" manifold with ten outlets, but rather to consider two smaller manifolds placed in different parts of the house (for example one for the ground floor, one for the upper floor). This shortens the individual circuits, reduces pressure loss, and results in more even heating.

Questions about installation and joining pipework

The third biggest group of questions concerns installation itself - specifically how to join the pipework and what to do when a joint starts leaking after a while.

Compression fitting or press fitting?

With the HEPWORTH system, in practice we most often encounter two ways of joining copper or plastic pipe - compression fittings (a mechanical joint with a union nut and a compression sleeve) and press fitting (a permanent joint made with press pliers). Both methods are reliable if done correctly, but they have different advantages:

Compression fitting - the advantage is that it can be taken apart and reassembled at any time (for example for servicing or replacing a component), you don't need expensive press tooling, and even a fairly experienced DIYer can handle the installation. The downside is a somewhat higher risk of leaking if the nut isn't tightened to the correct torque, or if the pipe wasn't properly cut and deburred before insertion.
Press fitting - faster with a large number of joints, more reliable with repeated installation by the same person, but requires investing in press jaws, and the joint can no longer be taken apart without cutting the pipe.

For a typical home installation, where future modifications are also expected (for example when renovating a bathroom or connecting another radiator), we recommend compression fittings - it's a more universal and repairable solution. That's exactly why the compression fitting for 15x1-EK copper pipe is one of the best-selling connecting parts in the entire HEPWORTH-related range.

Compression fitting - for copper pipe - 15x1-EK - the most commonly sold connecting part for connecting 15 mm copper pipe to a manifold or radiator valve, detachable and reusable. From €2.51.

A practical note that keeps coming up in our discussions: "Why did the joint start leaking after a year, even though I tightened it?" The most common cause isn't a faulty part, but an incorrectly prepared pipe end - an uneven cut, a burr left after cutting, or a scratch on the surface caused by the cutter. Before inserting into a compression fitting, always cut the pipe square, remove burrs from both the inside and outside, and check the surface for scratches at the spot where the sealing ring or compression sleeve will sit.

Diagram: compression fitting installation procedure

How do I correctly mount pipe to a wall or ceiling?

Mounting the pipework is often underestimated in practice, yet incorrect clip spacing is behind a large share of noise and pipe-sag complaints. The basic rule is simple: the pipe must not sag between mounting points and must not directly touch hard edges of the building structure (this causes the characteristic "ticking" sound as the water heats and cools). For machine-assisted mounting, clips joined together with wire into a strip are commonly used, which can be fitted quickly in large quantities at once - for example 45 mm HS clips.

HS clips 45mm for machine-assisted pipe mounting, joined with wire into a strip - a practical solution for quickly fitting a large number of mounts at once, also suitable for professional installation companies working with extensive pipework. From €21.77.

Approximate spacings we recommend as safe for horizontal pipe runs: for 15 mm bore roughly every 100 cm, for 20 mm every 120 cm, for 25 mm every 150 cm, and for 32 mm every 180 cm. For vertical runs (risers), the spacing can be slightly extended, but at penetrations through a ceiling or at a change of direction we always recommend fitting a mount right next to the elbow or tee.

Questions about operation - filtration, pressure, air in the system

Why do I need a filter at the water inlet?

This is a question we mainly deal with with people who fill their system from their own well or from a public mains supply with older pipework. Debris, sand and sediment accumulate over time precisely at the narrowest points of the system - in radiator valves, in the manifold, and in any circulation pump. Without filtration, these spots gradually clog up, showing up as uneven heating and rising energy consumption for moving the water.

A cyclonic sediment filter captures mechanical debris before it enters the system, and the cyclonic principle allows easy sediment removal without having to shut down the system or replace a cartridge. For a system fed from a larger bore (e.g. 4"), such a filter is fitted directly on the main feed before the manifold or before the boiler.

Cyclonic sediment filter 4" - 1/2"F - captures mechanical debris before it enters the pipework, protects the manifold, valves and circulation pump from clogging. From €102.34.

The recommended interval for checking and, if needed, draining sediment from the filter is once every one to two heating seasons; however, in the first year after installation (while dust from the installation work "settles"), we recommend checking the filter already after one to two months of operation.

How do I regulate the temperature on individual radiators?

Even in a system with a central manifold, it makes sense to fit thermostatic valves directly on individual radiators - this lets you fine-tune the temperature in a specific room independently of the others, for example a lower temperature in the bedroom and a higher one in the bathroom, without touching the settings of the whole system. A straight-type valve (no bend) is suitable where the supply pipe reaches the radiator along a straight axis.

Straight thermostatic radiator valve EK x 1/2

Thermostatic radiator valve - straight, EK x 1/2" - allows independent temperature control on each radiator without touching the rest of the pipework. From €8.58.

Diagram: approximate price comparison of basic components

What do I do when there's air in the system?

Bubbling in the radiators, or a cold top corner of a radiator with a warm bottom, is a classic sign of air in the system. In a system with a manifold, air most often accumulates at the highest point of the pipework or in the manifold itself, if it doesn't have a vent valve. The solution is simple - gradual venting from the circuit farthest away toward the source, checking the system pressure both before and after venting. If air keeps appearing in the system repeatedly (not just once after filling), it's almost always a microscopic leak through which air gradually gets into the system - in that case it's worth checking all the compression fitting joints, since that's where a leak most often occurs.

Questions about underfloor heating combined with HEPWORTH

The HEPWORTH system is also often combined with underfloor heating - in that case the manifold acts as the control point between the heat source (boiler, heat pump) and the individual circuits laid in the floor. The most common question is: "Can I connect both a radiator and underfloor heating to the same manifold?" The answer is yes, but with one important condition - underfloor circuits need a significantly lower water temperature (typically 35-45 °C) than radiators (typically 55-70 °C), so in practice either a separate manifold with a mixing unit is used for underfloor heating, or the whole system is run at a lower temperature suitable for both circuits at once (which is common especially with heat pumps). You'll find the detailed procedure in the article HEPWORTH for Underfloor Heating.

Diagram: four-circuit manifold layout

Maintenance and lifespan - the most common practical questions

How often does the system need checking?

We recommend a simple annual cycle: before the heating season starts (late September) check the system pressure, vent the radiators, and check the inlet filter. Halfway through the season (January), a visual check of joints on visible pipework sections (manifold, wall penetrations) is enough. After the season (April-May), we recommend a more thorough check, including draining sediment from the filter and checking that all the manifold's valves function correctly (closing and opening each one in turn, to prevent a valve that hasn't been used in a while from seizing).

How long does a HEPWORTH system last?

With correct installation and regular maintenance, the typical lifespan of the pipework is comparable to other good-quality plastic and copper systems - we're talking decades of operation. The lifespan of the individual fittings (valves, manifolds) is usually shorter than the pipe itself, since they contain moving parts (valve cones, seals) - we recommend checking these and replacing them if needed within a 10 to 15 year horizon, depending on how intensively the system is used and the water quality.

Can the system be expanded later, for example with an extension?

Yes, and that's exactly one of the advantages of a modular manifold-based solution - it's enough to choose a manifold with one or two extra free outlets at the original installation (for example a six-circuit manifold instead of a four-circuit one, even if you only use four for now). Connecting a new circuit to a free outlet later is significantly simpler and cheaper than replacing the whole manifold with a larger one after years of operation.

Frequently asked questions

Do I have to use components from a single manufacturer for a HEPWORTH system?

It isn't a strict requirement, but when connecting different systems (for example different types of compression fitting), thread and sealing surface compatibility needs to be verified. In practice, the safest approach is to stick to one proven component range for a given pipe bore - this limits the risk of small dimensional discrepancies that could cause a leak.

Do I need special tools to install a compression fitting?

No, unlike press fitting, ordinary plumbing tools are enough - a pipe cutter or hacksaw, a deburring tool, and two suitable wrenches for tightening the nut. This is exactly the main reason compression fittings are popular even among handy DIYers without professional equipment.

How often does the filter need replacing, or is draining sediment enough?

A cyclonic sediment filter with the cyclonic principle generally isn't replaced, just periodically drained (releasing captured debris via the drain valve at the bottom of the filter). The filter body itself has a lifespan comparable to the other fittings in the system, i.e. on the order of decades under typical home use.

Can I install a HEPWORTH system myself, or does it have to be a company?

Basic tasks like connecting a radiator via a compression fitting or replacing a valve can be handled by a handy DIYer alone. For bigger interventions - especially designing the whole pipework layout, sizing pipe diameters, and connecting to the boiler - we recommend consulting an installation company, since a design mistake affects the performance of the whole system, and fixing an already-finished installation later is always more expensive than getting the design right beforehand.

Why does my manifold "buzz" or make noise during operation?

The most common cause is too high a flow rate through a partially throttled valve (water passing through a narrowed opening at higher velocity, causing a characteristic hiss) or air trapped in the manifold body. First try fully opening the relevant valve and venting the manifold - if the noise persists even with the valve fully open, we recommend checking the circulation pump's setting, which may be set to a needlessly high output.

Can a heat pump be connected to a HEPWORTH system instead of a boiler?

Yes, the principle of the pipework and manifold stays the same regardless of the heat source type. The only difference is the water's operating temperature - heat pumps usually work with a lower water temperature than gas boilers, which is actually an advantage for underfloor heating, which directly requires lower temperatures.

Have a question on this topic?

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