Hamworthy Wessex 100 M100 Installation, Commissioning And Servicing Instructions

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Hamworthy Wessex 100 M100 Installation, Commissioning And Servicing Instructions Manual pdf 15 page image

HAMWORTHY HEATING LTD9WESSEX 100 M 500001080/Fsystem in a "reverse return" arrangement (the waterflow in each header is in the same direction) toensure equal flow in each module, or with a “singlepipe header system”. Figure 1.1 (p2) shows typicallayouts.5) Due to the higher pressure loss of the Wessexheat exchanger compared to the conventionalboilers, it may be necessary to install a shunt pumpor balancing valve to enable correct flow through theboiler.6) Ideally, individual valves should be fitted to eachmodule to enable isolation from the system,however, the arrangement must comply with therequirements of BS 6644. See Section 10.3 WaterConnections (p14).8.2 Pressure Relief Valve (Safety Valve)The most important single safety device fitted to aboiler is its safety valve and each boiler, or in thecase of a modular installation, each bank of boilers,must be fitted with a pressure relief valve to BS 759or BS 6759 Part 1 and sized as shown in BS 6644.BS 6644 provides comprehensive information forthe selection and location of safety valves andattention is drawn to the higher capacityrequirements of safety valves for pressurised hotwater systems.8.3 Open Vent and Cold Feed Pipe(See BS 6644 for further information.)Every boiler or group of boilers should have an openvent pipe and cold feed pipe installed between theboiler and the first water isolating valve. Theminimum bore (mm) of these pipes per installation isas follows:-The vent pipe must rise continually, must not bevalved except by a design which when closed formaintenance the boiler is open to atmosphere. Thepipe shall be protected against freezing where thismight occur.8.4 Altitude Gauge (Water Pressure Gauge)Every boiler or group of boilers should be providedwith a gauge complete with isolating cock. SeeFigure 1.1 (p2) for typical position.7.2 Air Supply by Mechanical VentilationAir supplied to the boiler room by Mechanical meansshould be as follows: -1) Mechanical inlet and mechanical extract can beutilised providing design extraction rate does notexceed one third of the design inlet rate.2) Mechanical extract ventilation with natural inletventilation MUST NOT be used.NOTE: For Mechanical ventilation systems anautomatic control should be provided to cut off thegas supply to the boiler, in the event of failure of airflow in either inlet or extract fans.8.0 WATER CIRCULATION SYSTEM8.1 GeneralThe Wessex Boiler has a low water content and therequirements of minimum water flow are given inSection 8.8: Minimum Water Flow Rates (p10)and Figure 2.2 (p4). Recommendations for the watercirculation system are given in BS 6644 and CP342. The following notes are of particularimportance:-1) In a combined central heating and hot watersystem, the hot water storage vessel must be of theindirect cylinder or calorifier type. The hot waterstorage vessel should be insulated preferably withnot less than 75mm (3 in) thick mineral fibre, or itsthermal equivalent.2) Circulating pipework not forming part of the usefulheating surface should be insulated to help preventheat loss and possible freezing, particularly wherepipes are run through roof spaces and ventilatedcavities. Cisterns situated in areas, which may beexposed to freezing conditions, should also beinsulated. Insulation exposed to the weather shouldbe rendered waterproof3) Drain valves must be located in accessiblepositions which permit the draining of the wholesystem, including the boiler and hot water storagevessel.4) Each boiler has G1½ male flow (indicated with ared spot) and return connections (indicated with ablue spot). Boilers should be connected by flow andreturn headers. Headers should be connected to theFigure 7.2 Mechanical Ventilation Flow RatesFlow rate per 1000kWtotal rated heat input (Gross)Inlet air(Combustionventilation)Extract air(ventilation)m³/s. m³/s.Volume 1.10 0.45AtmosphericBoilersFigure 8.3. Cold Feed and Vent Pipe SizesBoiler Output Feed Vent< 60 kW 19 2560 kW - 150 kW 25 32150 kW - 300 kW 32 38300 kW - 600 kW 38 50