Water Supply—Basic Requirements Water supply ~ an adequate supply of cold water of drinking quality should be provided to every residential building and a drinking water tap installed within the building. The installation should be designed to prevent waste, undue consumption. misuse. contamination of general supply. be protected against corrosion and frost damage and be accessible for maintenance activities. The intake of a cold water supply to a building is owned jointly by the water authority and the consumer who therefore have joint maintenance responsibilities. Typical Water Supply Arrangement ~ site boundary property of water authority property of BOREDEYECUBNOLEEE ity operty of consumer ~ see next page neck to relieve stress on connection due to pipe settlement — 150 mm internal diameter stop valve guard in clayware (BS 5834-1) cast iron surface box | expansion loop or goose | (BS 5834-2) 750 mm minimum ground for frost protection ——— mass concrete base to suit communication pipe | subsoil type at right angles to water authority main L_ stop valve Lwater main - fully charged with water under pressure 669Water Supply—Basic Requirements site boundary property property of consumer > to storage cistern and drinking water tap and main - see previous page < mene service pipe must not pass through a drainage inspection chamber pipes passing under foundations should be encased in mass concrete Service Pipe Materials ~ unprotected iron - not suitable unprotected steel - not suitable galvanised steel - may be acceptable to water authority lead - prohibited copper - BSEN 1057 acceptable plastic - blue polyethylene BS 6572. BS EN 12201-2 and uPVC BS 3505, BS EN 1452-2 are acceptable of water authority - 750 mm_minimum see previous unless insulated page against freezing | external wall——} ervice pipe or ising main {| drain down service or supply pipe minimum internal diameter ground 15 mm. level 1 IRV IARITTT R £ end of pipe a sealed with tostop valve plastic or € 9 8 ze “last 600mm of service pipe to be | insulated - | protective pipe to be | sealed with plastic or | mastic 75 mm diameter drain pipes as protection for service pipe under building 670Cold Water Installations General ~ when planning or designing any water installation the basic physical laws must be considered 1. Water is subject to the force of gravity and will find its own level. 2. To overcome friction within the conveying pipes water which is stored prior to distribution will require to be under pressure and this is normally achieved by storing the water at a level above the level of the outlets. The vertical distance between these levels is usually called the head 3. Water becomes less dense as its temperature is raised therefore warm water will always displace colder water whether in a closed or open circuit. Direct Cold Water Systems ~ the cold water is supplied to the outlets at mains pressure the only storage requirements is a small capacity cistern to feed the hot water storage tank. These systems are suitable for districts which have high level reservoirs with a good supply and pressure. The main advantage is that drinking water is available from all cold water outlets disadvantages include lack of reserve in case of supply cut off risk of back syphonage due to negative mains pressure and a risk of reduced pressure during peak demand periods. Typical Direct Cold Water System ~ 115 litre feed cistern to hot water cylinder 22 mm dia. overflow and warning pipe isolating valve— x Fe 15mm dia. rising main or service pipe 4 22 mm dio. cold teed pipe hot water storage cylinder a{ ‘5mm 15 mm dio — - aryl Basin 4) we press | sink stop valve» FV -Mtain off top or valve to water main —>ifl NB all pipe sizes given are outside diameters for copper tube 671Cold Water Installations Indirect Systems ~ Cold water is supplied to all outlets from a cold water storage cistern except for the cold water supply to the sink(s) where the drinking water tap is connected directly to incoming supply from the main. This system requires more pipework than the direct system but it reduces the risk of back syphonage and provides a reserve of water should the mains supply fail or be cut off. The local water authority will stipulate the system to be used in their area. Typical Indirect Cold Water System ~ cold water storage cistern minimum capacity 230 litres if used as a feed cistern and storage or 115 litres for storage only — dust proof cover i E32 mm dia, overflow = = and warning 4 Y pipe 22 mm dia. cold water q isolating distribution pipe ————>| valves. ;-WC cistern 140 litre hot water storage overflow pipe cylinder. 22 mm dia cold feed t 4 y pipe 4| 15mm] 15mm dia dia.— dia 4 15 mm dia. cold water distribution pipe 15 mm dia. service pipe ‘or rising main ——_____» I" 22 mm dia. overflow pipe — drinking water outlet —__»_ go we A drain valve stop valve ——m drain off tap or valve NB all pipe sizes given are outside diameters for copper tube 672Hot Water Installations Direct System ~ this is the simplest and least expensive system of hot water installation. The water is heated in the boiler and the hot water rises by convection to the hot water storage tank or cylinder to be replaced by the cooler water from the bottom of the storage vessel. Hot water drawn from storage is replaced with cold water from the cold water storage cistern. Direct systems are suitable for soft water areas and for installations which are not supplying a central heating circuit. Typical Direct Hot Water System ~ cold water storage cistern minimum capacity 230 litres Lroverttow 2 p<} = isolating valve ++ — 4 4 15 mm dia. service pipe ‘ 140 litre hot or rising main ——r} || woter storage 22 mm dia. cy indes cold feed 22 mm dia. open vent or expansion | pipe pipe to release air and relieve SO, pressure —— >| min = 15 mm = + ig asm BATH 22 mm dia. hot water supply pipe rf £ 28mm dia. primary | }e28 mm dia. tlow pipe —— 1} primary “ return pipe possible pumped secondary return [ Pipe) ft 15 mm dia. hot in hard water te 11 boite water supply pipe ‘areas primary 415. mm BASIN circuit pipes SINK diag. 4 z could be 35 mm drain valve diameter safety valve t Lo a ze NB all pipe sizes given are outside diameters for copper tube 673Hot Water Installations Indirect System ~ this is a more complex system than the direct system but it does overcome the problem of furring which can occur in direct hot water systems. This method is therefore suitable for hard water areas and in all systems where a central heating circuit is to be part of the hot water installation. Basically the pipe layouts of the two systems are similar but in the indirect system a separate small capacity feed cistern is required to charge and top up the primary circuit. In this system the hot water storage tank or cylinder is in fact a heat exchanger — see page 678. Typical Indirect Hot Water System~ 36 litre feed and expansion cistern cold water storage cistern overflows isolating a val 15 mm dia. }*22 mm dia. vent 4] 15mm dia service pipe or expansion service pipe or rising main > pipes» _ | or rising main 22 mm dia. i 140 litre indirect cold feed pipe——r>} hot water storage cylinder 4 gravity or pumped central 22 mm dia- heating circuit Bacal drain |y Zl 22 mm dia. ly i possible Ay 15 mm dia. hot water a] pumped , armory cold supply pipe —>| | secondary feed pipe — t return pipe }«+—28 mm dia. { primary flow Te = pipe ‘| [545 mm dia. hot oy [ water supply | exsm [* a] 28 m™ dia. pipe iY primary return SINK | pipe Tsafety | central heating valve | circuit boiler. drain valve—>. NB all pipe sizes given are outside diameters for copper tube 674Hot Water Installations Mains Fed Indirect System ~ now widely used as an alternative to conventional systems. It eliminates the need for cold water storage and saves considerably on installation time. This system is established in Europe and the USA, but only acceptable in the UK at the local water authority's discretion. It complements electric heating systems, where a boiler is not required. An expansion vessel replaces the standard vent and expansion pipe and may be integrated with the hot water storage cylinder. It contains a neoprene diaphragm to separate water from air, the air providing a ‘cushion’ for the expansion of hot water. Air loss can be replenished by foot pump as required. roof void without services secondary f thermal relief valve 1 flow { 1 y | prvf—s we hyd L [Less sare g | tS indirect _} hwsc primory—»| |-+— primary pressure return | 4] flow reducing ' valve) | heating boiler flow and therma rr return tf eens t ! SINK Le } | 1. expansion | Br ese = oe Core main suppl L fill ond with stop valve drain valves «check valve and double check valves NB. p.t.v. ~ pressure relief (safety) valve 675Hot and Cold Water Installations—Flow Controls Flow Controls ~ these are valves inserted into a water installation to control the water flow along the pipes or to isolate a branch circuit or to control the draw-off of water from the system. Typical Examples ~ wheel head yr head spindle spindle packing gland wedge shaped gore dl GATE VALVE STOP VALVE used to control flow of water used to stop flow of water seating piston nylon cap Seating arm PORTSMOUTH FLOATVALVE = DIAPHRAGM FLOATVALVE, capstan head spindle spindle packing gland easy clean cover packing a easy clean gland cover jumper outlet bib outlet BIB TAP PILLAR TAP horizontal inlet - used over vertical inlet - used in sinks and for hose pipe outlets conjunction with fittings 676Hot and Cold Water Installations—Cisterns Cisterns ~ these are fixed containers used for storing water at atmospheric pressure. The inflow of water is controlled by a floatvalve which is adjusted to shut off the water supply when it has reached the designed level within the cistern. The capacity of the cistern depends on the draw off demand and whether the cistern feeds both hot and cold water systems. Domestic cold water cisterns should be placed at least 750 mm away from an external wall or roof surface and in such a position that it can be inspected, cleaned and maintained. A minimum clear space of 300 mm is required over the cistern for floatvalve maintenance. An overflow or warning pipe of not less than 22 mm diameter must be fitted to fall away to discharge in a conspicuous position. All draw off pipes must be fitted with a gate valve positioned as near to the cistern as possible. Cisterns are available in a variety of sizes and materials such as galvanised mild steel (BS 417), moulded plastic (BS 4213) and reinforced plastic (BS 4994). If the cistern and its associated pipework are to be housed in a cold area such as a roof they should be insulated against freezing. Typical Details ~ overflow and warning pipe - minimum fell 1:10 ;—vent or expansion pipe oe i | 40 sy f floatvalve} | F stop = valve a “float | gote i LHe rising valve | draw off pipe LENT main cistern Wel ty ol I} bay ceiling pies Lite >] — insulation required under cistern when room below is unheated ceiling I root finish. timber platform on bearers insulation 677Indirect Hot Water Cylinders Indirect Hot Water Cylinders ~ these cylinders are a form of heat exchanger where the primary circuit of hot water from the boiler flows through a coil or annulus within the storage vessel and transfers the heat to the water stored within. An alternative hot water cylinder for small installations is the single feed or ‘Primatic” cylinder which is self venting and relies on two air locks to separate the primary water from the secondary water. This form of cylinder is connected to pipework in the same manner as for a direct system (see page 673) and therefore gives savings in both pipework and fittings. Indirect cylinders usually conform to the recommendations of BS 417-2 (galvanized mild steel) or BS1566 (copper) pohot water Typical Examples ~ supply outlet immersion heater hot water 1 boss cylinder secondary body air lock rimar _ pr y secondary vent pipe flow f water { primary corrugated poold teed primary heat exchanger — exchanger primary return primary return - primary water Lair locks INDIRECT CYLINDER "PRIMATIC' CYLINDER Primatic Cylinders ~ 1. Cylinder is filled in the normal way and the primary system is filled via the heat exchanger, as the initial filling continues air locks are formed in the upper and lower chambers of the heat exchanger and in the vent pipe. 2. The two air locks in the heat exchanger are permanently maintained and are self-recuperating in operation. These air locks isolate the primary water from the secondary water almost as effectively as a mechanical barrier. 3. The expansion volume of total primary water at a flow temperature of 82°C is approximately 1/25 and is accommodated in the upper expansion chamber by displacing air into the lower chamber, upon contraction reverse occurs. 678