TECHNICAL HANDBOOK for MULTISPLIT NETWORK SYSTEMS OR GROUP CONTROL DESCRIPTION * Compatible with IMPACT E, IMAGE E and IMAGE 600² E systems * Configurable as either group control or multisplit * Single indoor unit designated master * Master unit receives infrared and direct wired commands on behalf of all units * Prevents units from opposing each other when controlling the same environment NOTE: Products manufactured from January 1 st 1996 MUST use screened network cables to comply with the C.E. EMC Directive. Network PCBA (Part No. 53800689): This is required for units produced prior to January 1 st 1996, after that date networking is built in and this kit is not required. All members of a network must be of the same type, i.e., all having network PCBA's added or all having networking built in. Machines built from January 1 st 1996 are identified by the letters EMC on the packing to aid recognition during the transition period, see page 9 for details. NOTE: Indoor units produced prior to January 1 st 1996 must have printed circuit boards (53801239) and network compatible software (ID6.3 or higher). The network PCBA kit comprises: 1 x network printed circuit board 53801244 1 x link plug Refer to page 9 for kit installation instructions. One network board kit is required for each indoor unit. Interconnecting network cable (twisted pairs) is supplied by the installer. Two switches allow the board to be programmed, firstly as either Multisplit or Group Control and secondly as either Master unit or Slave unit. Full instructions are provided with the network kit. Multisplits DEFINITION: One outdoor/ducted unit serving a number of indoor units of total capacity equal to the outdoor/ducted unit's capacity. Multisplit control enables synchronized operation of all units in the multisplit system with the single master indoor unit. It also allows all the indoor units in the group to stop (and allows restart) of the common outdoor/ducted unit, through the master, in response to local alarms, e.g. high water level, etc.. Only the master can accept commands and instruct the outdoor unit. All the slaves mimic the master exactly, and go into cooling, heating or dead band simultaneously. The master controls the outdoor/ducted unit in response to any of the indoor units' local alarms; all units must run together or be OFF together. Using a multisplit manifold, one outdoor/ducted unit (MCU(+), MHPUE, DCUE or DHPUE) can be piped to one, or up to five indoor units (Impact E, Image E or Image 600² E). Sizing of the outdoor/ducted unit is simple; just add together the designatory numbers of the indoor units and select an outdoor/ducted unit equal to OR one size less than the total for MCU(+)/DCUE units, OR one size less than the total for MHPUE/DHPUE units, (see page 3 for examples). 53899162-02 -1-
Applications The multisplit system is suitable for use in large open plan spaces where the cooling or heating duty room shape requires the use of a number of indoor units. Typical applications in offices or retail space are shown below:- Group control DEFINITION: One indoor unit and one outdoor/ducted unit as a split system is linked to other split systems to form a group. Multiple single split systems serving a common area are linked to form a group with one 'Master' and up to 31 Slave systems. (Only the master can accept commands). The network control prevents units from 'fighting' each other, with some freedom permitted. Each indoor unit will carry out either the Master's current or previous operation (see the table below). MASTER SLAVES PREVIOUS OPERATION CURRENT OPERATION CURRENT OPERATION COOLING DEAD BAND COOLING OR DEAD BAND DEAD BAND COOLING COOLING OR DEAD BAND HEATING DEAD BAND HEATING OR DEAD BAND DEAD BAND HEATING HEATING OR DEAD BAND -2-
UNIT SELECTION When using indoor units which are ALL the same unit type and size, refer to the data sheets on pages 15 to 21 of this Handbook, otherwise see below. Suitable indoor units Any electronic Impact, Image or Image 600² unit can be used in the Multisplit system as illustrated in the application examples opposite. A full list of suitable units is as follows:- Impact Image Image 600² 20E 50E 20E 40E 70E 40E 60E 90E 60E 80E 120E 100E 160E Outdoor/Ducted unit selection Any condensing unit or heat pump from the MCU(+)/DCUE/MHPUE/DHPUE range is suitable for use in the multisplit system. Having selected the number and type of indoor units, the outdoor unit may be selected as follows:- 1 Add up the size designation of each indoor unit. 2 Condensing units Select the outdoor/ducted unit with a size designation equal to the total of the indoor units or the next size below. Heat Pump units Select the heat pump unit with a size designation equal to the next size below the indoor unit total. Examples of outdoor/ducted unit sizing Application 1 (as shown in Example 1). Indoor units Size designation Outdoor unit selection Image 70E 70 Image 70E 70 MCU(+) 130 Total 140 or MHPUE 130 Application 2 (as shown in Example 2). Indoor units Size designation Outdoor selection Image 120E 120 Impact 40E 40 Impact 40E 40 MCU(+) 200 Total 200 or MHPUE 180* Application 3 (as shown in Example 3). Indoor units Size designation Outdoor unit selection Impact 20E 20 Impact 20E 20 Impact 40E 40 Impact 40E 40 Impact 40E 40 MCU(+) 130 Total 160 or MHPUE 130 *Note: Selecting the next lowest outdoor unit will give a reduction in total duty but will result in a system with a higher sensible heat ratio. It is recommended that this option is used under the following circumstances:- 1 When long pipe runs are used with a higher suction line pressure drop. 2 If the system is designed to run at low speed and room conditions as low as 18 C for long periods, to reduce indoor unit frosting. -3-
PIPEWORK (refer to the diagram below) NOTE: This is a schematic diagram. All branch lines MUST have the same equivalent length. Fig. 1. Basic design The Multisplit system should run with a main suction and liquid line as far as the manifold assembly on cooling only systems. On heat pump systems the liquid line should be sized and treated as a main expansion line. The correct cooling expansion assemblies are located at the manifold assembly (see restrictor sizes, page 8). Expansion and suction lines connect the indoor units to the manifold assembly. Impact and Image 600² units require a heating restrictor to be used at the indoor unit on heat pump systems. It is recommended that the IMI manifold kit, Part Number 54000434, is used on systems with more than two indoor units, (refer to page 13 for installation). The use of this assembly will ensure good system balance and prevent condensation problems occurring at the manifold. Pipework Design Procedures The following procedure should be adopted when designing the pipework. 1 Total pipe run Determine the pipe run required. This should be no longer than 50m equivalent length, to any indoor unit. 2 Branch line length Determine the branch lines equivalent length, this must be no greater than 10m. All branch lines must have the same equivalent lengths to ensure that the system is correctly balanced. -4-
3 Total lift The total refrigerant lift, between the condensing unit and the indoor units, consists of the liquid line lift plus the expansion (branch) line lift. The maximum allowed total lift varies, dependant on the proportions of liquid line and expansion line. The chart (Fig. 2) shows the maximum expansion line lift for a given liquid line lift (or the maximum liquid line lift for a given expansion line lift). For example, if the liquid line lift is 4.5 m, the maximum expansion line lift allowed is 5 m, (see dotted line). 4 Manifold location Fig. 2. The correct position for the manifold can now be determined after calculating the total run, branch line length and total lift. Note: In calculating equivalent lengths of pipe runs, the effect of bends and fittings must be taken into account. Information concerning the equivalent lengths of line fittings and bends etc. is generally available to the design engineer. The table below covers fittings most likely to be encountered in this type of installation. The equivalent lengths of all the fittings in a particular pipe run must be added together and the total added to the actual length of pipe in the run, in order to calculate its total equivalent length. TYPICAL FITTING LOSSES, in equivalent straight lengths of pipe (metres). Pipe Size (outside diameter in inches) Fitting 3/8 1/2 5/8 3/4 7/8 1-1/8 1-3/8 45 Bend 0.12 0.15 0.18 0.21 0.24 0.30 0.40 90 Bend R/d = 1 0.37 0.43 0.49 0.55 0.61 0.79 1.00 90 Bend R/d = 1.5 0.24 0.27 0.30 0.37 0.43 0.52 0.70 180 Bend C/d = 1.5 0.73 0.91 1.10 1.28 1.46 1.83 2.38 180 Bend C/d = 2.5 0.46 0.55 0.64 0.76 0.85 1.07 1.40 90 Elbow 0.67 0.85 1.04 1.25 1.46 1.89 2.32 R = Radius of bend d = Diameter of tube C = Centres of bend The above figures should be used as a guide only - refer to the fitting suppliers information for precise data. -5-
5 Suction line sizing Main suction lines To allow the most cost effective installation, it is permissable to allow the main suction line pressure drop to reach 2 C, giving a 3 C total suction line drop. This will result in the following:- i) Up to a 7% loss of outdoor/ducted unit duty (see adjacent graph) ii) A reduction in evaporating temperature at the compressor of up to 2 C. iii) More frequent de-ice operation on the indoor coils. The use of a high main suction line pressure drop is not recommended for systems intended to run in the following conditions:- i) Systems where the sum of the nominal rating of the air handlers is the same as that of the outdoor/ducted unit resulting in a comfort system (refer to page 3 for unit selection). ii) Any system designed for regular cooling use at room temperatures below 20 C and low fan speed. Refer to the tables for main suction line sizing at 1 C and 2 C pressure drops. Note: Maximum equivalent length of line is 40 metres. Figures for 1 C Pressure Drop. Maximum equivalent length in Metres - Main Suction Line Size (Total Suction Line Drop = 2 C) Outdoor/Ducted Unit 1/2" 5/8" 3/4" 7/8" 1 1/8" 1 3/8" Outdoor/Ducted Unit Figures for 2 C Pressure Drop. Maximum equivalent length in Metres - Main Suction Line Size (Total Suction Line Drop = 3 C) 1/2" 5/8" 3/4" 7/8" 1 1/8" (D)MCU(+) 30 9.5 23 40 (D)MCU(+) 30 15 40 (D)MCU(+) 40 7.5 17 40 (D)MCU(+) 40 12 35 40 (D)MCU(+) 50 11 32 40 (D)MCU(+) 50 8 23 40 (D)MCU(+) 60 10 28 40 (D)MCU(+) 60 7.5 20 40 (D)MCU(+) 80 8 22 40 (D)MCU(+) 80 16 40 MCU(+) 90 13 26 40 MCU(+) 90 9 25 40 MCU(+) 100 11 22 40 MCU(+) 100 8 21 40 MCU(+) 130 9 18 40 MCU(+) 130 7.5 18 36 40 MCU(+) 165 7.5 13 40 MCU(+) 165 13 26 40 MCU(+) 180 9 32 40 MCU(+) 180 9 19 40 MCU(+) 200 7.5 21 40 MCU(+) 200 7.5 12 40 (D)MHPUE 30 9.5 23 40 (D)MHPUE 30 15 40 (D)MHPUE 40 7.5 17 40 (D)MHPUE 40 12 35 40 (D)MHPUE 50 11 32 40 (D)MHPUE 50 8 23 40 (D)MHPUE 60 10 28 40 (D)MHPUE 60 7.5 20 40 MHPUE 80 8 22 40 MHPUE 80 16 40 MHPUE 90 13 26 40 MHPUE 90 9 25 40 MHPUE 100 11 22 40 MHPUE 100 8 21 40 MHPUE 130 9 18 40 MHPUE 130 7.5 18 36 40 MHPUE 165 7.5 13 40 MHPUE 165 13 26 40 MHPUE 180 9 32 40 MHPUE 180 9 19 40-6-
Branch suction lines The branch suction lines to each unit must have the same equivalent length (maximum 10m) and should be sized as follows:- Maximum equivalent length in Metres - Branch Suction Line Size Indoor Unit 3/8" 1/2" 5/8" 3/4" 7/8" Impact 20E 7.5 10 Impact 40E 7.5 10 Impact 60E 10 Impact 80E 7.5 10 Impact 100E 10 Image 50E 10 Image 70E 10 Image 90E 7.5 10 Image 120E 10 Image 160E 7.5 10 Image 600² 20E 7.5 10 Image 600² 40E 10 Image 600² 60E 10 6 Liquid line sizing Main liquid lines The correct liquid line diameters may now be calculated by reference to the table below Note: Liquid lines must be insulated on heat pump systems and sized as an expansion line, (see main expansion lines). NOTE: Maximum equivalent length of line is 40 metres. Maximum equivalent length in Metres - Main Liquid Line Size Outdoor/Ducted Unit 3/8" 1/2" 5/8" (D)MCU(+) 30 40 (D)MCU(+) 40 40 (D)MCU(+) 50 40 (D)MCU(+) 60 32 40 (D)MCU(+) 80 26 40 MCU(+) 90 15 40 MCU(+) 100 12 40 MCU(+) 130 10 40 MCU(+) 165 26 40 MCU(+) 180 18 40 MCU(+) 200 12 40 7 Expansion Line Sizing Branch Expansion lines (maximum equivalent length is 10 metres) Maximum equivalent length in Metres - Branch Expansion Line Size Indoor Unit 3/8" 1/2" 5/8" Indoor Unit 3/8" 1/2" 5/8" Indoor Unit 3/8" 1/2" Impact 20E 10 Image 50E 7.5 10 Image 600² 10 Impact 40E 7.5 10 Image 70E 7.5 10 Image 600² 7.5 10 Impact 60E 7.5 10 Image 90E 7.5 10 Image 600² 7.5 10 Impact 80E 7.5 10 Image 120E 10 Impact 100E 7.5 10 Image 160E 10-7-
Main Expansion lines (applicable to heat pump systems only) The correct expansion line diameters may now be calculated by reference to the table below. Note: All expansion lines must be insulated. NOTE: Maximum equivalent length of line is 40 metres Maximum equivalent length in Metres - Main Expansion Line Size Outdoor/Ducted Unit 3/8" 1/2" 5/8" (D)MHPUE 30 7.5 40 (D)MHPUE 40 7.5 40 (D)MHPUE 50 7.5 40 (D)MHPUE 60 7.5 40 MHPUE 80 7.5 40 MHPUE 90 7.5 40 MHPUE 100 7.5 40 MHPUE 130 40 MHPUE 165 40 MHPUE 180 40 8 Restrictor sizing The correct restrictor size for each indoor unit should be selected by reference to the table below. Note: Impact and Image 600² units require a heating restrictor for heat pump use. IMPORTANT: These items must be purchased separately to the units and require an expansion assembly. Cooling Restrictor Part Number Heating Restrictor Part Number Indoor Unit Impact 20E 0.027 04603562S 0.027 04603562S Impact 40E 0.039 04603567S 0.037 04603604S Impact 60E 0.043 04603570S 0.044 04603571S Impact 80E 0.055 04603577S 0.054 04603576S Impact 100E 0.062 04603581S 0.058 04603579S Image 600² 20E 0.033 04603661S 0.035 04603586S Image 600² 40E 0.041 04603568S 0.039 04603567S Image 600² 60E 0.050 04603589S 0.041 04603568S Image 50E 0.043 04603570S Not required Image 70E 0.050 04603589S Not required Image 90E 0.054 04603576S Not required Image 120E 0.065 04603623S Not required Image 160E 0.069 04603585S Not required System charging The outdoor/ducted unit is supplied with a charge to suit a single split system, for all multisplit systems it will be necessary to add refrigerant. The recommended charging method is as follows:- Run the system with the standard charge and the charging link installed on the outdoor/ducted unit electronic board or with fan speed control terminals 1 and 2 linked together to run the fan at full speed on MCU(+) units. Add refrigerant to the system whilst monitoring the system temperature and pressures at the outdoor/ducted unit service valves. The correct level of charge has been reached when approximately 14k of superheat can be measured at the suction service valve, (at U.K. conditions, i.e., 21 C indoor, 27 C ambient). The charging link should then be removed and the level of suction superheat checked when the system is running with all indoor units at low speed. Failure to ensure adequate superheat will result in a reduced compressor life. Note: The only safe method of charging is as described above, charging to a full sight glass may result in a dangerously overcharged system. -8-
INBUILT NETWORKING APPLICATION Applicable to split systems having electronic indoor units Impact E, Image E and Image 600² E which contain printed circuit boards, part number 53801325. NOTE: ALL CIRCUIT BOARDS IN A NETWORK MUST BE THE SAME PART NUMBER; DO NOT MIX BOARD TYPES. Group Control (Master/Slave): Multisplit: Where a number of indoor units in one area are to control to the same temperature and not oppose each other. Where a number of indoor units are piped from one outdoor/ducted unit. The control strategies are different, see descriptions: Interconnecting network data cable, (0.22mm 2-0.75mm 2 ), is supplied by the installer. Group control (master/slave) 1 x 2 core cable with overall screen Multisplit 1 x 2 core cable or 1 x 4 core cable with overall screen (see page 11) On group control, the cable is run from the master unit to a slave and onward to the next slave etc. Avoid proximity to mains wiring. With multisplits, the cable links all the machines in a ring. Definitions Master Slave Standalone = Broadcaster of commands = Receiver of network commands = Not a qualifying member of network Group Control (Master/Slave) Local Group - Description: Each split system is installed and commissioned as instructions supplied with units. Additionally run a 2 core data cable from each unit to the next in line. One indoor unit is designated the master and this unit will receive infrared or hard wired commands for the whole group. All other units are slaves and execute exactly the master's commands in respect of ON / OFF / TIMED commands. * FAN SPEED CHANGE * If auto is selected, each unit will run at a speed consistent with it's local ambient. New master commands are sent to slaves immediately and refreshed every 5 seconds. Each unit controls the temperature of it's own locality to the common, (i.e., master), set point, entering dead band when satisfied. The control strategy does not allow a slave to oppose the master, e.g. Master cooling, slave may cool or be in dead band. Master in dead band following cooling, slave may cool or be in dead band. Master in heating, slave may heat or be in dead band. Master in dead band following heating, slave may heat or be in dead band. If a slave is not required to operate, it may be turned off by the normal local handset OFF button command, however, a slave is not allowed to run unless the master is running. Commands accepted at a master return one 'beep' Commands refused (because unit is a slave) return 3 'beeps' -9-
Multisplit Installation (also refer to the detailed diagram on page 23). A multisplit system's indoor units should be considered as one machine and are usually all situated in one area. Only the master can accept commands and instruct the outdoor unit. The slaves mimic the master exactly except in fan auto which is dependent on local temperature. Temperature measurement is done at the master's location so it is important that this unit is positioned to be representative of the mean room condition. All commands given to a slave are refused with 3 'beeps'. Commissioning ANY NETWORK TYPE 1 Ensure that the indoor board is part no. 53801325. 2 Select the master unit and fit one of the link plugs provided (taped to the transformer) to position 'MAS' on the indoor board. Do not fit links to any other position. 3 On all other units in the system, fit a link plug at position 'SLA' on the indoor board. Do not fit links to any other position. MULTISPLIT NETWORKS 4 In addition, fit a link plug to position 'SPLIT' on the master and ALL the slave units. 5 Network wiring Do not run network wiring in close proximity to mains wiring. Earth the network cable sheaths at both ends with the clamps provided. Secure the cable sheaths to an adjacent hole in the terminal box in IMAGE units, (using a cable tie), or with the plastic clamps provided in IMPACT units. It is recommended that the cable ends are identified with labels because a network will only work if an output from one unit is connected to an input of the next unit. It will also help fault finding if a plan is made showing the relationship of the slaves to a master i.e., first slave, second slave etc. Impact E Connect external network cables directly to the control boards, (see opposite). Image E Connect external network cables to the strip connector in the terminal box. Image 600²E Use EMC termination kits 55200301, one per 600²E (one termination can accomodate up to 3 cables; type 00526077). -10-
Master - Slave Multisplit 6 Power up all units - Check that the master unit accepts all commands with a single 'beep'. - Check that slaves reject temperature/fan speed change commands with three 'beeps'. - Check that all units start and stop together when commands are sent to the master (ensure that all slaves are initially locally commanded to 'on' in the case of a master slave group). Refrigerant Charging Set the master indoor unit to Maximum Fan Speed before fitting the charge link JP6 to electronic outdoor units or bypassing the fan speed control on MCU(+) to allow refrigerant to be added. DIAGNOSTICS (additional to single split system diagnostics) Group Control, (Master - Slave) 1 All units return 3 'beeps' to a temperature or speed change command - no unit is properly set up as a master - check links. NOTE: Only one Master per group is allowed. 2 Units do not operate together - units not correctly set up as a master or a slave. (How many 'beeps'? one = master/standalone, three = slave) - Check links are set correctly - Network wires crossed or open circuit, or 'IN' wires connected to 'OUT' terminals or vice versa. Note: Group controlled machines will default to stand alone operation after approximately 3 minutes. - Fault or no power at the master 3 Amber LED 2 F at master flashes at 0.5 sec. intervals with beeps lasting for 30 seconds, Multi link fitted to master - remove it. Multi-split As for master-slave faults 1 and 2 plus:- 4 Amber LED2 F at master flashes (with beep lasting for 30 seconds). - Break in network loop, see network multisplit wiring. - Fault, lack of power at one/some unit(s) - observe lights, on all units - 'IN' wires connected to 'OUT' terminals or vice versa. 5 Slaves running but master not running - Master is not communicating to slaves which will go into deadband with fan running. - Lack of supply/failure of master unit 6 Fan goes to maximum speed in cooling and most green led's are off - Unit with green led on has an icing evaporator coil - refrigeration problem. 7 Random stopping of the outdoor unit for up to 3 minute periods without alarm. - Temporary low pressure - 28 psi Air Conditioner; 5 psi Heat Pump Further information If problems are encountered with the slaves seeing infrared commands intended for the master and returning an echo of 3 beeps. - Direct signals into the master from close to the unit - Hard wire the handset to the master - Blocking reception of any signals at a slave other than over the network can be achieved by coupling a wire between terminals 1 and 3 of JP15 on the indoor board. -11-
INTERFACE WITH BUILDING MANAGEMENT SYSTEMS A basic B.M.S. interface is provided. RUN A unit (standalone or master) programmed by handset to be permanently on i.e., no time programmes, may be turned OFF/ON by a volt free relay contact of a B.M.S. 1 Cut link R7 ensuring that the free wire ends do not touch any other conductor/component. 2 Make connection to the B.M.S. as shown IMAGE to external terminal box, terminals 6 and 13 IMPACT directly to the circuit board, terminals JP15/1 and T2 RUN. NOTE: Once R7 has been cut, a board can be restored to normal operation by fitting a wire link between T2 RUN and T2 ALARM. ALARM By fitting a B.M.S. alarm interface kit, a simple common alarm signal is available for volt free input to a B.M.S. Power failure or any other notifiable alarm state causes the output relay to de-energise Condition OK = system running without fault Condition Alarm = system mains power loss or notifiable alarm state. IMPACT-E IMAGE-E / IMAGE 600²E -12-
5 WAY MANIFOLD KIT 54000434 INSTALLATION ADDITIONAL COMPONENTS PER UNIT CONTENTS (to be ordered separately) ITEM QTY DESCRIPTION QTY DESCRIPTION 1 1 Manifold Assembly 1 Cooling Restrictor (Indoor Unit) 2 2 Support Bracket 1 Heating Restrictor (IMPACT/IMAGE 600² Heat Pumps) 3 6 No. 10 Screw 1 Expansion Device (IMPACT/IMAGE 600² Heat Pumps) 4 3 Flow Control Housing ADDITIONAL COMPONENTS PER UNIT WHEN 5 3 Flare Nut Adapter USING MORE THAN 3 INDOOR UNITS 1 Expansion Device 1 1/2" Flare Nut Adaptor This kit is for use on a multisplit system where one outdoor unit (MCU(+), MHPUE, DCUE or DHPUE) can be piped to up to five indoor units (IMPACT-E, IMAGE-E or IMAGE 600²-E). If more than 3 indoor units are to be piped to the manifold assembly, the additional items detailed in the above table will be required. INSTALLATION The location of the manifold can only be determined after calculating the total run, branch line length and total lift as described on pages 4 to 8. NOTE: It is not necessary to remove the cover from the manifold box during installation. 1 The manifold box can be mounted in four positions, (refer to Fig. 3), depending on the routing of the pipework. Fig. 3. 2 Secure the two support brackets to the manifold with the No. 10 screws. -13-
3 Ensure that the mounting surface is capable of supporting the manifold assembly's weight (7.5 kg) and mark out the two mounting holes. Drill to suit M6 Rawlbolts or fasteners of equivalent strength. Ensure that there is sufficient work space to fit the expansion devices and secure the pipework. Always ensure that the indoor units are connected symmetrically about the centre of the manifold assembly, e.g., 3 units, use connections 2, 3 and 4 4 units, use connections 1, 2, 4 and 5 (see Fig. 3 overleaf). 4 Ensure that the correct restrictors are fitted in the expansion assemblies, (refer to the table on page 8), and secure onto the appropriate connection on the manifold box. Ensure that all expansion assemblies connected to the manifold box are fully insulated. 5 Remove and discard the expansion assembly connected to the outdoor/ducted unit. 6 Check the tables on pages 6 to 7 or the data tables on pages 15 to 22 for the correct sizes and install the interconnecting pipework, (Fig. 1, page 4). -14-
IMI Air Conditioning Ltd. Armytage Road, Brighouse, West Yorkshire. HD6 1QF. Tel: (01484) 405600. Fax: (01484) 721949. A subsidiary company of IMI plc. -24-