24i RSF WALL MOUNTED COMBINATION BOILER FOR CENTRAL HEATING AND MAINS FED DOMESTIC HOT WATER INSTALLATION AND SERVICING INSTRUCTIONS GC NUMBERS N.G. 47 311 37 L.P.G. 47 311 38 BOILER OUTPUT To Domestic Hot Water – Modulated Control Minimum 7.5 kW (25,600 Btu/h) Maximum 23.4 kW (80,000 Btu/h) To Central Heating – Modulated Control\ Auto Range Rated Minimum 7.5 kW (25,600 Btu/h) Maximum 23.
Contents 1. Installation Requirements . . . . . . . . . . . . . . . . . . . . . . . . . Page 2 2. General Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 2 3. Data Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 4 4. Siting the Appliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 5 5. Siting the Flue. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Page 6 6. Air Supply . . . . . . . . . . . . . .
Fully modulating controls in the central heating and domestic hot water modes of operation. An expansion vessel, pressure gauge and pressure relief valve. A fixed by-pass for the central heating system. A Temperature safety cut-out control. A water flow regulator. A standard telescopic horizontal flue assembly giving flue lengths from 330mm to 725mm. Optional extra extension flue kits to provide for flue lengths up to 2500mm.
The data plate is fixed to the inner casing cover. 3. Data Tables Table 1 kW Btu/h 7.5 23.4 (25,600) (80,000) NOMINAL BOILER RATINGS BURNER SETTING INPUT (Net). PRESSURE kW Btu/h m bar. in. wg. NATURAL GAS 9.60 (32,750) 1.0 0.4 26.05 (88,890) 13.6 5.4 7.5 23.4 (25,600) (80,000) 9.60 26.05 OUTPUT GAS RATE 3 m /h ft3/h 1.01 2.76 35.7 97.5 0.39 1.07 13.9 37.8 PROPANE (32,750) (88,890) 3.5 35.0 1.4 14.0 Table 2.
4. Siting The Appliance Fig. 2. Appliance casing dimensions and required clearances.
5. Siting The Flue 6. Air Supply See Fig. 3. 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. 5.3 If a terminal is fitted less than 2 metres above a surface to which people have access then a guard must be fitted. See Section 2.9. 5.4 The terminal guard must be evenly spaced about the flue terminal and fixed to the wall using plated screws. 5.
.7 The filling point must be at low level. See Fig. 4. 7.8 Water loss must be replaced. See Fig 4. The connection should be made in the central heating return as close to the appliance as possible. A filling loop kit is supplied. 7.9 Repeated venting loses water from the system. It is essential that this water is replaced and the system pressure maintained. 7.10 Connections to the mains water supply must not be made without the authority of the local Water Company. 7.
9.10 No anti-syphonage arrangements are necessary except for some loose head showers. See also Section 9.11 following. 9.11 Thermostatically controlled or pressure equalising shower valves will guard against the flow of water at too high a temperature. 9.12 The head of a loose head shower must not fall closer than 25mm (1in.) above the top edge of the bath to prevent its immersion in bath water.
be used in conjunction with a programmer. Important: To provide external frost protection the appliance must have the Central Heating Temperature Control Knob set to supply heating (the appliance may then be left with the central heating turned off on the programmer). Connection must be made at X2 terminals RI and CL. For advice on external frost thermostats contact Worcester Heat Systems Technical Helpline 10.11 SAFETY CHECK.
CH control POT DHW temp. sensor CH temp. sensor X6 Pins 3 & 4 Flow signal Outputs X6 Pins 19 & 20 Air pressure switch X6 Pins 1 & 2 X6 Pins 15 & 16 X6 Pins 5,6 & 7 Modulating valve X6 Pins 8 & 9 Overheat stat Fig. 9. Functional flow diagram. Inputs FAN X4 Pin 3 X4 Pin 1 LOW VOLTAGE ELECTRONICS (Microcontroller) RL1 PUMP X3 Pin 1 Mains indicator X3 Pin 2 RL3 X5 Pin 3 GAS VALVE F2 1.
Technical Helpline. 11. Installing The Appliance Mark the centre-lines of the pipe connections to aid the preplumbing of the system pipework. Check the position of the fixing points and the flue opening before drilling the fixing holes 60mm deep for the No.12 size plugs and cutting the flue duct hole at 110mm diameter (150mm diameter for internally fitted flues. 11.5 Wall Mounting Plate and Manifold Fit the plugs and fix the top support to the wall. Refer to Fig. 10.
The standard telescopic flue assembly is suitable for flues from425mm (without cutting) up to 725mm measured from the centre-line of the boiler flue outlet to the outer face of the wall. Refer to Fig. 14. Fig. 12. Appliance casing and control equipment fixings. If L is greater than 725mm then flue extension kits will be required - each kit extends the flue by 750mm up to a maximum of 2500mm. See table below.
Fig. 15. Extension Duct. L Turret assembly Terminal assembly Fixing screws Fixing screw Ducts of equal length Appliance casing Shorten first extension fitted to the turret assembly if more than one extension is fitted Fig. 17 . Rear flue. Fig. 16. Flue duct length (side flue).
Fig. 18. Flue Turret Fixing . Fig. 19. Terminal assembly for internal fitting of the flue. 1 5 1 2 3 1. 2. 3. 4. 4 3 4 2 Flue turret Clamp Appliance Fixing Screw 1. Flue centering ring 2. Air duct 3. Flue duct 4. Rubber sealing gasket 5. Flue Terminal Rubber sealing gasket 11.12 Flue Bends 90° and 45° bends are available. A maximum of two bends may be used in addition to the first bend on the flue turret. A 90° bend is equivalent to 750mm of straight duct.
Fig. 21 - Elbow to Flue Turret Assembly. Fig. 23 - Facia Connections Cover. 120mm 1 2 100mm Flue Turret Bend 3 1. Control Panel Fixing Screws 2. Facia 3. Control Panel Pivot Point 4. Connection Cover 5. Connection Cover Fixing Screws Fig. 22 Vertical Adapter. Flue Duct Air Duct 5 4 11.14 Completion of the Installation Check that all the connections on the appliance have been tightened. Remove the facia bottom panel. Refer to Fig. 23.
12. Commissioning The Appliance Fig. 27. Appliance components and fixings (upper assembly). Flue hood Benchmark Water Treatment: For optimum performance after installation, this boiler and its associated central heating system should be flushed in accordance with the guidelines given in BS7593:1992 - Treatment of water in domestic hot water systems. Full instructions are supplied with proprietary cleansers sold for this purpose.
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 100 litres. Refer to BS 7074 Part 1. If the system volume is in excess of that accommodated by the expansion rises. Fully close the tap and check that the burner goes off.
13. Instructions To The User 14. Inspection And Service 13.1 Tell the user how to operate the appliance and hand over the Users Instructions leaflet. 13.2 Tell the user what to do if the heating system is not to be used in frosty weather. 13.3 Tell the user the sealed system set pressure. 13.4 Tell the user of the importance of regular servicing. Worcester Heat Systems Ltd. offer a comprehensive maintenance contract. 13.5 Set the system controls to the user’s requirements. 13.
14.3 DISMANTLE THE APPLIANCE To carry out a full and comprehensive service of the appliance remove the following parts to gain access to the components which need to be checked or serviced. (d) Bottom panel. Unclip and remove the appliance bottom panel. (e) Fan. Remove the inner casing cover. Carefully unplug the electrical connections and pull off the sensing tubes. Unscrew the four fixing screws and remove the fan assembly. See Fig. 32. (f) Combustion Chamber Front. Remove the inner casing cover.
2. Air Pressure Switch. See Fig. 36. Check that the electricity supply to the appliance is turned off. Remove the cabinet front panel as described in Section 14.3 (a) and lower the facia. Section 14.3(c). Carefully pull off the sensing tubes and the electrical connections from the switch. Remember to note their positions. Unscrew the two screws behind the Air Pressure Switch and remove the switch from the appliance.
Restart the appliance in central heating mode and adjust the minimum adjustment screw on the gas valve to give a pressure of 1.0 mbar on natural gas or 3.5 mbar on propane. See Fig. 35. After completing the adjustments, check the minimum and maximum pressures and re-adjust as necessary. Once this has been done the clear cap should be re-fitted to the adjuster and the retaining screw tightened. Coat the screw with paint or nail varnish to prevent user adjustment. 6. Combustion Chamber Insulation.
sink compound between the faces. Refit the leads. 13. Domestic Hot Water Sensor. Check that the electricity supply to the appliance is turned off. Hinge the facia assembly in the servicing position as described in Section 14.3(c and d). Carefully pull off the two leads from the sensor. Undo and remove the clamping screw. Pull off the sensor and spring retaining clip from the pipe. Fit the replacement sensor in the reverse order ensuring a layer of heat sink compound is between the faces. Refit the leads.
20. Control Board. Check that the electricity supply to the appliance is turned off. Undo the 3 screws and remove the facia bottom panel. Remove the two upper screws and hinge down the facia assembly. Carefully pull off all the connectors. Disconnect the mains supply lead at terminal X1 and the earth connection at the back. Remove the four corner screws on the back of the facia and separate the metal back panel from the plastic facia. Remove and retain the brass nut and washer.
Pump on Water flow temperature monitored by central heating sensor Escape pause by resetting the mains electricity supply OFF-ON Is fan in overrun mode? YES NO Wait (pump on in central heating mode) FAIL Air pressure switch test PASS AUTOMATIC START-UP SEQUENCE Internal "Autofrostat" demand CENTRAL HEATING DEMAND Operating Switch (or programmer) and room thermostat on End of a domestic hot water overrun 1.
Inhibit operations for approximately 1 second. 6 second delay before reignition from any other demand. Run pump Burner pressure at 1.
CH control POT DHW temp. sensor CH temp. sensor X6 Pins 3 & 4 Flow signal Outputs X6 Pins 19 & 20 Air pressure switch X6 Pins 1 & 2 X6 Pins 5,6 & 7 Modulating valve X6 Pins 15 & 16 X6 Pins 8 & 9 Overheat stat 18. Fault Finding Inputs FAN X4 Pin 3 X4 Pin 1 LOW VOLTAGE ELECTRONICS (Microcontroller) RL1 PUMP X3 Pin 1 Mains indicator X3 Pin 2 RL3 X5 Pin 3 GAS VALVE F2 1.
Fault in Domestic Hot Water Fault in Central Heating Is mains LED flashing? YES GO TO CHECK D YES NO NO Is mains LED illuminated? NO GO TO CHECK C NO Is mains LED iluminated? YES YES Is control knob set for demand? Is mains LED flashing? NO Turn control knob fully clockwise NO Ensure link is fitted at X2 pins 5 & 6 NO Set room stat to call for heat NO Ensure link is fitted at X2 pins 2 & 3 YES Is a room thermostat fitted? YES Is room thermostat calling for heating? YES Is programmer
No mains LED Is mains present at X1 pins 1 & 3? NO Connect mains supply YES Is F1 (2ATHRC) OK? NO Replace fuse YES Is F2 (1.
Overheat Thermostat Check The overheat thermostat can be reset by pressing the reset button, but if it trips immediately or on a regular basis a serious problem has occurred therefore contact your installer Reset thermostat Does button hold in? NO Is capillary broken? YES YES Is capillary firmly ATTACHED to exchanger? NO Replace overheat thermostat ATTACH to heat exchanger YES GO TO CHECK I Pump Check Is pump connector secure on the PCB (X3)? NO Secure Connector YES Is mains present at the pump
Thermistor Check Remove connectors from thermistor YES Is resistance between terminals of thermistor between 690ohms & 33k? NO Faulty thermistor YES Thermistor OK Harness Continuity Check Remove appropriate connectors YES Is continuity observed between each end of wire in question? NO Faulty harness or connector YES Harness OK Harness Short Check Remove appropriate connectors YES Is short circuit observed between pair of wires in question? NO Faulty harness YES Harness OK 30
Ignition Check Is fan running? NO GO TO CHECK G NO GO TO CHECK E NO Is sparking present at the electrodes? YES Does sparking occur? GO TO CHECK L Faulty PCB Replace YES Does ignition occur? NO YES YES Are ignition leads connected both ends securely? Are leads breaking down? YES Replace leads NO YES Is flame sense electrode in flame? NO Ensure flame sense electrode in flame at minimum burner pressure YES Is lead secure both ends? NO YES GO TO CHECK I HARNESS OK Faulty PCB Replace Do
L Air Pressure Switch Check Remove BROWN and WHITE terminals from air pressure switch With no demand, is a short-circuit observed at exposed APS terminals? NO Air pressure switch faulty YES Reconnect the WHITE & BROWN wire and remove the GREEN wire. Initiate a demand. Does the fan run? NO YES Fan or fan cable faulty YES With fan running disconnect BROWN wire. (DO NOT touch chassis with it).
N Modulating Valve Check Is minimum pressure observed at burner at all times? YES Remove X6, measure resistance between pins 15 & 16 NO GO TO CHECK I NO Is resistance nominally 125ohms? YES Is pressure at burner always the same? YES NO With pressure above minimum, remove Modureg Lead. Does pressure drop to minimum? NO Faulty modulating valve . Replace gas valve Reconnect X6 and measure voltage across modulating valve during operation YES Gas valve OK YES Does voltage go above 6.
19. Component Parts List Key No. 1 G.C. No.
9 8 14 3 21 1 15 22 4 13 12 7 11 10 20 23 23 25 24 2 35 6 19 18 16
This manual is to be used in conjunction with the variant part number of the bar code below: Worcester Heat Systems Limited (Bosch Group), Cotswold Way, Warndon, Worcester WR4 9SW. Telephone: (01905) 754624. Fax: (01905) 754619. Technical Helpline 08705 266241. www.worcester-bosch.co.uk 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.
