Bosch Group 28CDi RSF WALL MOUNTED COMBINATION BOILER FOR CENTRAL HEATING AND MAINS FED DOMESTIC HOT WATER INSTALLATION AND SERVICING INSTRUCTIONS GC NUMBER 47 311 34 (N.G.) GC NUMBER 47 311 35 (L.P.G.) BOILER OUTPUT Automatic Modulating Control Minimum Maximum To Domestic Hot Water 9.0 kW 28.0 kW To Central Heating 9.0 kW 24.
Contents 1. 2. 3. 4. 5. 6. 7. 8. 9. Installation Regulations .............................................. Page General Information .................................................... Page Technical Data .............................................................. Page Siting the Appliance .................................................... Page Siting the Flue Terminal .............................................. Page Air Supply ....................................................................
The boiler requires 3.35 m3/h (115 ft3/hr) of natural (G20) or 1.29 m3/hr (46 ft3/hr or propane gas (G31). The gas meter and supply pipes must be capable of supplying this quantity of gas in addition to the demands of any other appliances being served. The meter governor should deliver a dynamic pressure of 20 mbar (8in wg.) for natural gas or 37 mbar (14.4 in wg.) for propane. The complete installation, including the gas meter, must be tested for soundness and purged. Refer to BS 6891. 2.
The data plate is fixed to the inner casing cover. Check data plate to ensure appliance has been adjusted for supply gas. 3. Technical Data Table 1 Btu/h (30,700) (81,888) (95,536) NOMINAL BOILER RATINGS (10 Minutes After Lighting) BOILER ADJUSTED FOR G20 (Natural Gas) BURNER SETTING INPUT PRESSURE kW Btu/h m bar. in. wg. 11.4 (38,897) 1 0.4 27.0 (92,124) 8.8 3.5 31.5 (107,478) 12.1 4.8 3 m /h 1.2 2.9 3.3 ft3/h 42.5 102.7 116.9 (30,708) (81,888) (95,536) BOILER ADJUSTED FOR G31 (Propane) (38,897) 3.
Notwithstanding the instructions given in BS 5440:2, this appliance may be fitted in a compartment with no vents as long as the minimum clearances stated in Section 6: Air Supply, are maintained. 4.7 The airing space must be separated from the boiler space by a perforated non-combustible partition. Expanded metal or rigid wire mesh are acceptable provided that the major dimension is less than 13mm. See BS 6798:1987. 4.8 No combustible surface must be within 75mm of the casing. See BS476:4. 4.
5. Siting The Flue Terminal 6. Air Supply See Fig. 4 6.1 The appliance does not require a separate vent for combustion air. 6.2 The appliance can be fitted in a cupboard with no vents for cooling but the minimum clearances must be increased to those given below. (Note: The clearances at the front are for a removable panel, e.g. a door). 5.1 The flue must be installed as specified in BS 5440:Part 1. 5.2 The terminal must not cause an obstruction nor the discharge cause a nuisance. 5.
fitted as shown). Insert the bayonet end of the filling key into the corresponding cut outs in the filling loop housing and twist to lock the key in place. Turn the grey knob anti-clockwise to allow water ingress and fill until the required pressure is reached. Turn the grey knob clockwise to stop filling and remove the filling key by lining up the bayonet end of the key with the cutouts in the filling loop housing and withdrawing the key. N.B.
.4 A pressure relief valve is not required on an open vented system. 8. Open Vent Primary Systems 8.5 Air within the appliance will be expelled via the feed and vent connection or dissipated into the rest of the system which must be fitted with manual air vents at any high point. 8.1 The size of the flow and return pipework is given in Section 3 – Table 4. The components required to connect the appliance to an open vent system are available as an optional extra kit. 8.
10.10 The boiler is fitted with an internal frost thermostat which will protect the boiler from frost damage, as long as the mains switch on the boiler is in the on position. However, if frost protection is necessary for the system, please contact Worcester Heat Systems Technical Helpline. Tel: 0990 266241. 10.11 SAFETY CHECK.
LIVE IN ST12 Pin N ST12 Pin L Fuse F1 (2A Slow) On/Off switch 10 ST1 Centre Pin Low High ST1 Pin L Convert AC to low voltage electronics ST15 Pin L REL 4 ST8 (LR) Spark Indicators Red Settings Red DHW CH demand demand indicator indicator Electronics/ microprocessor (Safety Low Voltage) REL 3 Optional link Room thermostat ST8 (NS) Transformer Fuse F2 (1.
Fig. 11. 230 V room thermostat connections. NS LS LR Spare Remove link Switched live Live Neutral ST8 Fig. 12. 230 V programmer connections. NS LS LR Spare Switched live Live Neutral ST8 Motor Fig. 13. 230 V room thermostat and programmer connections.
Flue components 1. Appliance casing sealing gasket 2. Flue Turret 3. Flue Collar 4. Air duct to turret sealing ring 5. Standard air duct 6. Standard flue duct 7. Restrictor ring 8. Flue terminal 9. Extension air duct 10. Extension flue duct 11. Flue duct sealing ring 12. In-line flue elbow 13. Vertical flue adaptor 11. Installation The appliance is supplied suitable for fitting to a sealed system. If it is to be fitted to an open vent system refer to section 8. 11.1 FLUE OPTIONS.
NOTE: READ THIS SECTION FULLY BEFORE COMMENCING INSTALLATION 11.2 GENERAL FITTING. Check that the appliance carton contains: Appliance, installers instruction pack, pre-plumbing manifold, wall plate cross member, user’s information pack and installer’s hardware pack. Assemble the wall plate cross member to the pre-plumbing manifold as shown in Fig. 14 using the two M4 thread forming screws supplied in the hardware pack.
Fig. 19. Flue elbow, ducts and terminal assembly Fig. 21. Terminal assembly for internal fitting of the flue. Flue duct length = L + 181mm (rear flue) L + 210mm (side flue) Rubber sealing gasket Air duct length = L + 146mm (rear flue) L + 175mm (side flue) Fixing screws Flue terminal Clamping ring Restrictor ring Seal these joints Appliance casing Flue terminal L Fig. 20. Flue assembly using extension kits.
tightened. If a facia mounted programmer is to be fitted follow instructions with the programmer.. Hinge down the facia as described in Section 14.3(c). Connect the mains electrical supply to the appliance at terminal ST 12 See Fig. 8. Connect any room and/or frost thermostats. The electrical leads must pass through the appropriate space in the control panel and be fixed with the cable clamps provided. See Figs. 11 and 12. Refit the facia panel.
Check that the pressure relief valve operates by turning the knob anticlockwise until it releases. Water should be expelled from the discharge pipe. See Fig. 24. Lower the control box to gain access. Refer to Section 14.3(c). Set the Expansion Vessel Pressure The charge pressure of the expansion vessel as dispatched is 0.5 bar, which is equivalent to a static head of 5 metres (17 ft). The charge pressure must not be less than the static head at the point of connection. See Fig. 7.
Set the movable pointer on the pressure gauge to coincide with the indicating pointer giving a permanent record of the set system pressure. If the pressure indicated on the pressure gauge is greater than 2.6 bar when operating at the maximum central heating temperature, an extra expansion vessel must be fitted to the system as close as possible to the appliance central heating return connection. The appliance (as dispatched) can accommodate a system volume of about 83 litres. Refer to BS 7074 Part 1.
13. Instructions To The User 14. Inspection And Servicing 14.1 SERVICING To ensure continued efficient operation of the appliance it must be checked and serviced as necessary at regular intervals. The frequency of servicing will depend upon the particular installation conditions and usage, but once per year should generally be adequate. The extent of the service required by the appliance is determined by the operating condition of the appliance when tested by fully qualified engineers.
assembly from the appliance. See Fig. 28. When refitting the hood ensure that the rear return edge passes under the lip at the rear of the combustion chamber. (g) Combustion Chamber Front and Sides. Remove the inner casing cover and flue hood assembly. Unscrew the two wing nuts securing the front and sides and remove from the appliance. See Fig. 28. (h) Burner Assembly. Remove the combustion chamber front and sides. Pull off the two spark electrode leads and disconnect the flame sense lead.
AIR PRESSURE SWITCH 2. Air Flow Pressure Switch. See Fig. 30. Check that the electricity supply to the appliance is turned off. Remove the cabinet front panel as described in Section 14.3 (a). Carefully pull off the sensing tubes and the electrical connections from the switch. Unscrew the two screws underneath the gas valve and remove the switch and bracket from the appliance.
13. Central Heating Sensor. See Fig. 31. Remove the inner casing cover as described in Section 14.3(b). Check that the electricity supply to the appliance is turned off. Carefully pull off the two leads from the sensor. Pull off the sensor and spring retaining clip from the pipe. Fit the replacement sensor in reverse order with a layer of heat sink compound between the faces. Refit the leads. 14. Domestic Hot Water Sensor. Check that the electricity supply to the appliance is turned off.
16. Short Parts List Key No. G.C. No.
109 23
17 Operational Flow Diagrams 24
18. Fault Finding Note: This fault-finding information is for guidance only. Worcester Heat Systems cannot be held responsible for costs incurred by persons not deemed to be competent. The electronic control system for this boiler incorporates four lights on the facia. These are used to show normal operating status. But as a secondary function, by flashing, they can also be used to help provide fault diagnostics.
Bosch Group Worcester Heat Systems Limited, Cotswold Way, Warndon, Worcester WR4 9SW. Telephone: (01905) 754624. Fax: (01905) 754619. Technical Helpline (0990) 266241. This booklet is accurate at the date of printing but will be superseded and should be disregarded if specifications and/or appearances are changed in the interests of continued improvement. All goods sold are subject to our official Conditions of Sale, a copy of which may be obtained on application.
