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It should be connected to the system, preferably at the same point as the expansion vessel. Its location should be visible from the filling point. © Baxi Heating UK Ltd 2009 4.0 System Details Temporary Hose Mains Water Stop Supply Valve (Service Pipe) Double Check Valve Heating System Filling a Sealed Water System (Method 1) Mains Topping Up Method NOTE: This method of filling a sealed system Fig. 7 may only be used if acceptable to Local Water Undertaking Hose Union Mains Water Supply Cistern Pressure Pump Reducing Valve Stop Valve Heating System Filling a Sealed Water System (Method 2) Cistern Filling Method Fig. 8 NOTE: Cistern to be supplied through a temporary connection from a service pipe or cold water distributing pipe (if required) Vessel Charge Pressure (bar) 0.5 1.5 Initial System Pressure (bar) 1.0 1.0 Expansion Vessel Volume (litres) V x 0.11 V x 0.087 Table 1 © Baxi Heating UK Ltd 2009 4.7 Sealed Systems (cont) 4. Expansion Vessel. A diaphragm type expansion vessel to BS 4814:1 shall be fitted close to the inlet side of the pump. The connecting pipework should not be less than 15mm. Pipework connecting the expansion vessel should not incorporate valves of any sort. Methods of supporting the vessel are supplied by the vessel manufacturer. The nitrogen or air charge pressure of the expansion vessel shall not be less than the hydrostatic head, (height of the top point of the system above the expansion vessel). To size the expansion vessel it is first necessary to calculate the volume of water in the system in litres. The following volumes may be used as a conservative guide to calculating the system volume. Boiler Heat Exchanger: 1.55 litres Small Bore Pipework: 1 litre per kW of system output Micro Bore Pipework: 7 litre Steel Panel Radiators: 8 litre per kW of system output Low Water Capacity Radiators: 1 litre per kW of system output Hot Water Cylinder: 1 litre per kW of system output If the system is extended, the expansion vessel volume may have to be increased unless provision has been made for extension. Where a vessel of the calculated size is not available, the next available larger size should be used. The boiler flow temperature is controlled at approx. 75°C. The vessel size can now be determined from the information in table 1 where V = System volume in litres. 5. Cylinder. The hot water cylinder must be an indirect coiler type. 6. Method of Make Up. Provision shall be made for replacing water loss from the system either:a) From a make up vessel or tank mounted in a position higher than the top point of the system and connected through a non-return valve to the system on the return side of the hot water cylinder or the return side of all heat emitters. or b) Where access to a make up vessel would be difficult by using the mains top up method or a remote automatic pressurisation and make up unit. 7. Mains Connection. There shall be no connection to the mains water supply or to the water storage tank which supplies domestic hot water even through a non-return valve, without the approval of the Local Water Authority. 8. Filling Point. A filling point connection on the central heating return pipework must be provided to facilitate initial filling and pressurising and also any subsequent water loss replacement/refilling. The sealed primary circuits may be filled or replenished by means of a temporary connection between the circuit and a supply pipe, provided a ‘Listed’ double check valve or some other no less effective backflow prevention device is permanently connected at the inlet to the circuit and the temporary connection is removed after use. The filling method adopted must be in accordance with all relevant water supply regulations and use approved equipment. Your attention is drawn to: for GB: Guidance G24.2 and recommendation R24.2 of the Water Regulations Guide. for IE: the current edition of IS 813 “Domestic Gas Installations”. 5.0 Site Requirements 5.1 Builders Opening (Fig. 9) 1. The boiler unit is designed to fit within a standard builders opening, the minimum dimensions of which are as shown. 560mm minFireplace Opening 390mm min 490mm max 584mm min 595mm max5570mm min Builders Opening (575mm max Valour DimensionRegalia ONLY ) Height 570mm Width 584mm Depth 305mm 2. The opening should be soundly constructed of brick, pre-cast concrete or be a proprietary builders opening. 3. The base of the opening should be sound and noncombustible and must be flat and level. 4. The base of the builders opening should be at the same height as the finished level of the hearth. SURROUND OR FINISHED WALL FACE 560mm minimum590mm maximum570mm minimum 305mm minimum Solid, non combustible hearth to support the boiler, as specified in BS 5871.HEARTH LEVEL IMPORTANT: If a false chimney breast is intended to house the boiler, a simulated builders opening, within the breast, must be provided. 5. The builders opening must not communicate with voids, pipe ducts or spaces other than the room in which the ...