PHAM NEWS | FEBRUARY 2024 Pipes, Fittings& Valves 19


Rigid or fl exible? What’s best for the job in hand


When it comes to pipes for heating and plumbing, the choice is metal or plastic. But what’s best for which installation? Richard Bateman from RWC looks at the question in light of some of today’s key concerns, including cost, ease, sustainability and performance.


exception is in some healthcare piping applications, where stainless steel is more regularly seen. Plastic pipes are typically made from polybutylene or cross-linked polyethylene (PEX), which can either be used separately, or in conjunction with each other.


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On your metal For the most part, there are three situations where using metal is more suitable. The fi rst is for gas applications, where copper is the choice. The second is for direct connection to a boiler. That’s not to say plastic pipes can’t do the job. In fact, they’re specially designed for direct connection, but some cleaners and inhibitors could damage the plastic. For that reason, we recommend using copper for the fi rst metre of piping from the boiler itself. The third situation where


metal has an advantage, is where the pipework’s on show and it needs to look a certain way. While you can paint plastic pipes, most people agree that metal defi nitely has the edge when it comes to aesthetics. After that, plastic and metal


are pretty much interchangeable – even for applications such as internal water supply. They do the same job and come in the same diameters – so size isn’t an issue. So, if they can perform the


same job, what are the pros and cons of each? That really comes down to four areas of most interest to installers: ease, cost, performance, and sustainability.


Easy does it There’s no doubt that plastic is much easier to work with than metal, and that’s important when you’re trying to push through heavy workloads or deal with tricky installations. Most metal pipes come in


rigid straight lengths which need to be cut to size and fi tted to shape. Plastic polybutylene


Richard Bateman Product marketing manager at RWC


s a general rule, copper is the most commonly used metal in plumbing pipework; the only


pipes are usually supplied in coils which means you can run continuous lengths with fewer joints, and in tight confi ned spaces. It’s good for all projects, especially retrofi t where the pipework challenges are rarely straightforward. Because it can quickly and easily be formed into loops, plastic is also ideal for underfl oor heating or when you’re running pipes through joists or in confi ned spaces. It’s not just space that’s tight


either. These days, with the rising cost of materials, budgets are too – and that’s another reason to think plastic.


There’s no doubt that plastic is much easier to work with than metal, and that’s important when you’re trying to push through heavy workloads or deal with tricky situations


KEY POINTS


 We recommend using copper for the fi rst meter of piping from a gas boiler


 While you can paint plastic, metal has the edge when it comes to aesthetics


 Because of its fl exibility, plastic is ideal for applications such as UFH or running pipes through confi ned spaces


 The use of fewer fi ttings with plastic pipe means that there is less risk of leaks


 Wrapping plastic pipes in foil when used in stud walls will aid location with a wall scanner


Value for money Metre for metre, plastic pipes come in at about a quarter of the cost of metal – and that quickly adds up to good value. Even better, unlike metal pipes which require connections at regular intervals, plastic can bend round corners and be manipulated into place without extra fi ttings, saving you money as well as time. Fewer fi ttings also mean less risk of leaks and less remedial work – an important consideration when the majority of pipework is hidden out of sight. Speaking of things out of


sight… people often think that plastic is more susceptible to rodent attacks. The truth is rats and mice don’t discriminate. They have phenomenal teeth which will eat through anything in their way, be it bricks concrete or even metal. The issue here isn’t the pipe, it’s the creature. Pest control is outside of a plumber’s job description, therefore, it’s always best to check that there are no known rodent issues prior to installing pipework in areas that may be susceptible to rodent attacks, such as loft spaces, cellars or basements.


Durable option While metal is often thought of as durable, plastic scores highly too – more so in some cases. For example, when water freezes copper pipes don’t expand, which can result in damage to the pipe. This issue has been


eliminated in the JG Speedfi t PEX Barrier Pipes and JG Layfl at Polybutylene Pipes. Both have a fi ve-layer construction including a barrier layer, which prevents any air ingress and, in turn, any airlocks forming within the system, which ensures that any expansion or contraction will only aff ect metal fi ttings.


Which plastic? For many installers, the choice isn’t always between metal and plastic, but about which type of plastic. The good news here is there’s a binary choice. Polybutylene is a highly fl exible ‘bendy’ pipe that lays fl at straight from the coil. PEX also comes in coils and can be bent but is a little more rigid and harder to manipulate. Actually, you could use either for pretty much any application, but really, they’re more suited to certain situations. Due to their material


properties, polybutylene pipes such as JG Layfl at are fl exible and easy to manipulate into a range of positions. PEX pipes are also available in coils, but the material is slightly more rigid, making PEX pipes slightly harder to manipulate compared to PB alternatives. In the case of JG Layfl at, the pipe coils are designed to stay fl at as the pipe is removed from the reel, which makes the pipe extremely easy to use and prevents kinking. For polybutylene pipes, when you need a bend, you simply


create the shape you want, and it will hold in place with pipe clips. This makes installation quick and easy, saving time and eff ort. It’s best suited for anywhere requiring non-linear pipework including underfl oor and retrofi ts or, for example, fi tting a new dishwasher into a kitchen. It can also be used for straight applications, making it ultra fl exible. However, there are times


when a more rigid application is required. This includes a straight run to an appliance or up through a wall.


Tips and guidance So, both PEX and polybutylene will serve you well, whatever your need. Whichever you choose, it’s important to follow the manufacturer’s instructions and install them correctly. Of these instructions, perhaps the most important of all is to make sure you’re using the right sized pipe insert in solid fl oor applications, high-risk areas and whenever you’re working through walls. Getting this right protects the pipe from damage caused by thermal expansion. Another useful tip for when


pipes run through stud walls is to wrap them in foil. No, not to keep them warm, but to allow you to locate them easily with a wall scanner. You’d be surprised how many pipes get pierced during picture hanging or other DIY activities. ◼ phamnews.co.uk/224/32


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