Guidance Notes Hot and Cold Water and Central

Uniclass EPIC JS1 L7116 P71 G111 X71 CI/SfB (53) (56) In6 March 2014 GUIDANCE NOTES PLASTIC PIPES GROUP HOT AND COLD WATER AND CENTRAL HEATING PLASTIC PIPE SYSTEMS HOT AND COLD In service the systems have many benefits over traditional materials. WATER AND These include reduction in mechanical CENTRAL HEATING noise, no scale build up (as the smooth PLASTIC PIPE internal bore reduces the accumulation of limescale), and lack of corrosion. SYSTEMS No solder is required (which complies with Water Supply (Water Fittings) INTRODUCTION Regulations 1999). The pipes do not Plastic pipe systems are available in easily fracture when frozen as thermal a wide variety of materials. The most expansion is accommodated within the common are Polybutylene (PB) and length of a pipe run. Finally, low thermal Cross Linked Polyethylene (PEX), conductivity means that pipes carrying including barrier pipe that incorporates hot water are cooler to the touch. an oxygen barrier, and multi-layer The extensive range of fittings available composite pipes (MLC). These pipe for each pipe system enables reliable, systems can be used in hot and cold watertight joints to be made quickly water supply and central heating and easily in a wide variety of installations; in fact in most areas domestic and commercial systems. where traditional piping materials are used. APPLICATIONS The flexibility of the pipes, particularly Plastic pipe systems manufactured those manufactured in PB or PEX, from PB and PEX are available provides easy handling and installation. Kitemarked to class ‘S’ of BS 7291-1 They are available in both straight (Thermoplastics pipes and associated lengths and coils, which enables fittings for hot and cold water for ‘threading’ around obstructions domestic purposes and heating and through joists etc., reducing installations in buildings-Part 1:General Key – Table 1 the number of joints required. MLC requirements) – which ensures that l Excludes boiler vent pipes pipes retain their formed shape. n Excludes discharge pipes from temperature they are safe for all classes of service and/or pressure relief valves conditions shown in table 1.The current s Where a nominal working pressure does not edition of the standard is dated 2010. compromise an integer value, the mantissa is expressed in a Fractional format. This is done to reduce the possibility of misinterpretation or obscurity that could cause a system to be subjected to an excessive pressure Table 1 – Classification of Service Conditions t 1 bar = 105 N/m2 = 105 kPa Nominal Maximum System System System Flow System Service Malfunction Maximum Temperature (Tf) Temperature (Ts) Temperature (Tm) Working Pressure s APPLICATION ln °C °C °C BAR t Indirect cold 20 20 - 31/2 water systems Direct mains-fed cold 20 20 - 12 water systems Subsurface 60 83 100 31/2 heating systems Vented hot 65 83 100 31/2 water systems(1) Unvented hot water systems including instantaneous heaters 65 95 100 6 and/or incorporating storage(1) Vented central heating systems and indirect hot 82 95 100 31/2 water primary circuits Sealed central heating systems and indirect hot 82 105 114 3 water primary circuits (1)Continuously operated re-circulating systems are excluded from these applications – see page 10 for further details 2 CODES OF PRACTICE Plastic pipe systems should be designed and installed in accordance with the following standards and guides: BS 5449:1990 Specification for forced circulation hot water central heating systems for domestic premises. BS EN 12828:2003 Heating systems in buildings. Design for water-based heating systems. BS EN 12831:2003 Heating systems in buildings. Method for calculation of the design heat load. BS 5955-8 :2001 Plastics pipework (thermoplastics materials). Specification for the installation of thermoplastics pipes and associated fittings for use in domestic hot and cold services and heating systems in buildings. BS 6700:2006 Specification for design, installation, PRODUCT RANGES testing and maintenance of services Plastic pipe systems come in a wide Pipes are available in nominal supplying water for domestic use variety of types. Those Kitemarked to diameters of 10 to 110mm to within buildings and their curtilages. Class ‘S’ of BS 7291 are suitable for cover a wide range of applications. BS 8000-15:1990 the applications described previously. Different manufacturers’ supply different size ranges. Workmanship on building sites. The following information provides an Code of practice for hot and cold outline of the wide choice available in Pipes are available as straight lengths water services (domestic scale). plastic pipe systems. Care should be or coils. Coiled pipes are supplied in PAS 33 taken to ensure that the jointing longer lengths, which can be threaded Specification for the design, installation mechanism and fittings used are those in continuous runs through the fabric and commissioning of gas fired central recommended by the manufacturer of a building reducing the number of heating systems in domestic premises. for the system. joints required. Water Industry Act 1991 Plastic pipe systems are available in A wide variety of fittings are available Water Supply (Water Fittings) a range of plastic materials including to cater for all installation requirements. Regulations 1999. polybutylene, PPSU and cross-linked Manufacturers also offer their own polyethylene. range of accessories such as conduit The Building Regulations 2000 pipe, pipe clips, pipe clip spacers, cold Barrier pipes generally have an (approved documents A, G and L). forming bends, pipe cutters etc. intermediate polymeric layer bonded The manufacturers’ brochures should to the pipe wall on either side by an be consulted for the full range of adhesive layer that forms a barrier to fittings available for each system and the passage of oxygen. In MLC systems their compatibility with other systems. an intermediate layer of metal, such as aluminium is bonded between the two plastic layers. 3 JOINTING SYSTEMS INSTALLATION A variety of jointing systems are General available for plastic pipe systems. General information on installing Care should be taken to ensure that plastic pipe systems is given below. the correct jointing mechanism for the However, the manufacturer’s installa- system is used. To ensure the jointing tion instructions should always be system is compatible, the relevant followed for each specific system. manufacturer’s literature should be Many manufacturers run their own consulted. The most common jointing training schemes, and information system in the UK for domestic on these can be obtained direct applications is the push-fit. A support from the manufacturer. sleeve is inserted into the pipe end and the pipe simply pushed firmly Pipe Cutting into the fitting to an insertion mark or Pipes should be cut using the specified depth. A quick tug back on manufacturer’s recommended pipe the pipe ensures the joint is secure. cutter. A hacksaw or craft knife should Push fit joints incorporate a rubber seal never be used since this can leave and a gripping mechanism to provide a roughened or out-of-square end. a secure mechanical connection. They The cut pipe should be checked for are generally ‘demountable’ either by burrs or scoring and any roughness, unscrewing or by using a special tool. grit, dirt or swarf should be removed Other systems include prior to jointing. • Mechanical compression jointing Jointing the fitting compresses the pipe The widely used push fit joints are ensuring the tightness of the joint made by first inserting a pipe support without the use of any sealing sleeve into the pipe. It is essential to material. Special tools are sometimes use a support sleeve in order to make required and a support sleeve should a good joint. The support sleeve must always be used. be pushed fully into the pipe end. • Press fit jointing The pipe is then pushed firmly into incorporating a metal outer sleeve the fitting. To ensure the pipe has been and plastic or metal body with pushed to the full socket depth, ensure integral inserts. the insertion depth marks on the pipe Using a special power tool the align with the outer end of the fitting. outer sleeve is pressed to grip the If insertion marks are not marked on pipe to the fitting body. the pipe or the pipe is being installed • Fusion jointing in an area where the marks are not the pipe and fitting are heated until clearly visible then the insertion their surfaces melt. The two molten depth can be marked on the pipe surfaces are brought together in advance of jointing using a suitable and joined. As they cool the two marker. Manufacturer’s literature surfaces fuse together. Special tools should be consulted for the correct are required. insertion depths. Most push fit joints are capable of being rotated and • Electrofusion dismantled. This enables the joints similar to the above but electrofusion to be re-aligned or dismantled after is used to melt the surfaces. installation and some or all of the components may be re-used in re-assembly. The manufacturer’s instructions should be followed and in some cases a special tool may be required. For other jointing techniques the manufacturer’s literature should be consulted. 4 CONNECTION TO OTHER SYSTEMS Many plastic pipe systems, especially the push fit ranges, can be connected to other pipe materials. Copper pipe The copper pipe should be cut square, using a wheel cutter. Before jointing ensure the pipe ends are free from burrs or swarf and undamaged or dented. Where specified by the manufacturer an appropriate copper pipe end-protector should be inserted. Connection to metric copper pipe to BS EN 1057 (Copper and copper alloys. Seamless, round copper tubes for water and gas in sanitary and heating applications) can be made using most push fit connectors. Connection to other copper pipe sizes will require a change of ring seal in the fitting or use of an appropriate adaptor.

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