10 Mexico Super RS485 - RS4125 - Installation & ServicingGENERALSizing procedure for expansion vessels: The volume of the expansion vessel (litres) fitted to a sealed system shall not beless than that given by Table 5, multiplied by a factor of 0.8 (for flow temperatures of less than 88 oC).Safety valve setting 3.0 bar 2.5 bar 2.0 barVessel charge and initial 0.5 1.0 1.5 0.5 1.0 1.5 0.5 1.0system pressure bar bar bar bar bar bar bar barTotal water content of system Expansion vessel volume(litres) (litres)25 2.1 2.7 3.9 2.3 3.3 5.9 2.8 5.050 4.2 5.4 7.8 4.7 6.7 11.8 5.6 10.075 6.3 8.2 11.7 7.0 10.0 17.7 8.4 15.0100 8.3 10.9 15.6 9.4 13.4 23.7 11.3 20.0125 10.4 13.6 19.5 11.7 16.7 29.6 14.1 25.0150 12.5 16.3 23.4 14.1 20.1 35.5 16.9 30.0175 14.6 19.1 27.3 16.4 23.4 41.4 19.7 35.0200 16.7 21.8 31.2 18.8 26.8 47.4 22.6 40.0225 18.7 24.5 35.1 21.1 30.1 53.3 25.4 45.0250 20.8 27.2 39.0 23.5 33.5 59.2 28.2 50.0275 22.9 30.0 42.9 25.8 36.8 65.1 31.0 55.0300 25.0 32.7 46.8 28.2 40.2 71.1 33.9 60.0Multiplying factors forother system volumes 0.0833 0.109 0.156 0.094 0.134 0.237 0.113 0.207. Mains ConnectionThere must be no direct connection to the mains watersupply or to the water storage tank supplying domesticwater, even through a non-return valve, without the approvalof the local water authority.8. FillingThe system may be filled by one of the following methods:a. Through a cistern, used for no other purposes, via aball valve permanently connected directly to a servicepipe and / or a cold water distributing pipe.The static head available from the cistern should beadequate to provide the desired initial system designpressure. The cold feed pipe from the cistern shouldinclude a non-return valve and a stop valve with anautomatic air vent connected between them, the stopvalve being located between the system and theautomatic air vent. The stop valve may remain openduring normal operation of the system if automaticwater make-up is required.b. Through a self-contained unit comprising a cistern,pressure booster pump (if required) and, ifnecessary, an automatic pressure reducing valve andflow restrictor. The cistern should be supplied througha temporary connection from a service pipe or coldwater distributing pipe.This unit may remain permanently connected to theheating system to provide limited automatic watermake-up. Where the temporary connection issupplied from a service pipe or distributing pipewhich also supplies other draw-off points at a lowerlevel then a double check valve shall be installedupstream of the draw-off point.c. Through a temporary hose connection from a draw-off tapsupplied from a service pipe under mains pressure. Wherethe mains pressure is excessive a pressure-reducing valveshall be used to facilitate filling.The following fittings shall form a permanent part of thesystem and shall be fitted in the order stated:A stop valve complying with the requirements ofBS. 1010, Part 2 (the hose from the draw-off tap shall beconnected to this fitting).A test cock.A double check valve of an approved type.ï Thoroughly flush out the whole of the system with coldwater, without the pump in position.ï With the pump fitted, fill and vent the system until thepressure gauge registers 1.5 bar (21.5lb/in 2).Examine for leaks.ï Check the operation of the safety valve by manuallyraising the water pressure until the valve lifts. Thisshould occur within ± 0.3 bar (± 4.3lb/in 2.) of the pre-setlift pressure.ï Release water from the system until the initial systemdesign pressure is reached.ï Light the boiler and heat the system to the maximumworking temperature. Examine for leaks.ï Turn off the boiler and drain the system while still hot.ï Refill and vent the system.6 SEALED SYSTEM REQUIREMENTS - continuedTable 5