22mm termination from boiler, increase to 32 mm if external Cement mortar sealing 500 mm min. 2Ѕ fall O Ground level (either/or) 25mm 100mm plastic tube 300mm Bottom of tube sealed Two rows of 3 x 12mm holes at 25mm centres, 50mm from the bottom of the tube. Holes to face away from house. Soakaway depth 400mm filled with limestone chippings Fig. 4.8 - External soakaway 4.11 DOMESTIC HOT WATER SYSTEM The minimum flow rate needed for the flow switch and burner to operate is 1.5 litres/min. If the mains supply is fitted with a water meter, check valves or loose jumper stop cock, then a DHW expansion device must be fitted.
If the incoming mains water pressure is above 5 bar a pressure reducing valve must be fitted. Following Part L Building Regulations, where the mains water hardness exceeds 200 parts per million, provision should be made to treat the feed water to the hot water circuit of combination boilers to reduce the rate of accumulation of limescale. To ensure economic use, the pipe runs between the boiler and taps should be in 15 mm copper pipe and be as short as possible. Where possible the pipework should be insulated to reduce heat loss. All taps and mixing valves used with the hot water system must be suitable for operating at a mains pressure of up to 8 bar.
Showers - A shower may be used with the boiler if required. If a loose or flexible head type shower is used it may require the fitting of a double check valve, to comply with Water Bye Law 17. Bidets - No anti-syphonage arrangements are necessary, provided the outlets are shrouded and it is not possible to attach a temporary hand held spray. A supply of direct mains fed hot and cold water is permitted provided the appliance is of the over-rim flushing type. Before the mains water supply pipe is connected to the boiler, it should be thoroughly flushed out to avoid the danger of dirt or foreign matter entering the boiler. 16 Alpha E-Tec 28 and 33 - General Boiler Information