Ideal Boilers LOGIC MAX HEAT H 18 Installation & Servicing

Also see for LOGIC MAX HEAT H 12: User guide

17Installation and ServicingSECTION 1 - GENERALSEALED SYSTEM REQUIREMENTS - continuedautomatic 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, if necessary,an automatic pressure reducing valve and flowrestrictor. The cistern should be supplied through atemporary connection from a service pipe or cold waterdistributing pipe.This unit may remain permanently connected to theheating system to provide limited automatic watermake-up. Where the temporary connection is suppliedfrom a service pipe or distributing pipe which alsosupplies other draw-off points at a lower level then adouble check valve shall be installed upstream of thedraw-off point.c. Through a temporary hose connection from a draw-offtap supplied from a service pipe under mains pressure.Where the mains pressure is excessive a pressurereducing valve shall 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 shallbe connected to this fitting).A test cock.A double check valve of an approved type.• Thoroughly flush out the whole of the system with coldwater, without the pump in position.• With the pump fitted, fill and vent the system until thepressure gauge registers 1.5 bar. Examine for leaks.• Check the operation of the safety valve by manuallyraising the water pressure until the valve lifts. Thisshould occur within ± 0.3 bar of the preset liftpressure.• Release water from the system until the initial systemdesign pressure is reached.• Light the boiler and heat the system to the maximumworking temperature. Examine for leaks.• Turn off the boiler and drain the system while still hot.• Refill and vent the system.• Adjust the initial pressure to the required value.4. Expansion Vessela. A diaphragm type expansion vessel must beconnected to a point close to the inlet side of thepump, the connecting pipe being not less than 15 mmsize and not incorporating valves of any sort.b. The vessel capacity must be adequate to accept theexpansion of the system water when heated to 110 o C.c. The charge pressure must not be less than the staticwater head above the vessel. The pressure attained inthe system when heated to 110 o C should be at least0.35 bar less than the lift pressure of the safety valve.For guidance on vessel sizing refer to the table inthis section.For further details refer to BS. 5449, BS. 7074:1 andthe British Gas Corporation publication ‘Materialand Installation Specifications for Domestic CentralHeating and Hot Water’. For IE refer to the currentedition of I.S.813.5. CylinderThe cylinder must be either of the indirect coil type or adirect cylinder fitted with an immersion calorifier which issuitable for operating on a gauge pressure of 0.35 barin excess of the safety valve setting. Single feed indirectcylinders are not suitable for sealed systems.6. Make-up WaterProvision must be made for replacing water loss from thesystem, either:a. From a manually filled make-up vessel with a readilyvisible water level. The vessel should be mounted atleast 150 mm above the highest point of the system,and be connected through a non-return valve to thesystem, fitted at least 300 mm below the make-upvessel on the return side of the domestic hot watercylinder or radiators.orb. Where access to a make-up vessel would be difficultby pre-pressurisation of the system. Refer to ‘Filling’,below.7. 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 theapproval of 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 theSizing procedure for expansion vessels: The volume of the expansion vessel (litres) fitted to a sealed system shall not be lessthan that given by the table on the following page, multiplied by a factor of 0.8 (for flow temperatures of less than 83o C).continued . . . . .