Heating and hot water for the professionals
Installation and Servicing Instructions

THEMA F

THIS IS A CAT II2H3+ APPLIANCE
IN WARRANTY TECHNICAL HELPLINE

01773 828400

01773 828100
INSTALLATION AND SERVICING INSTRUCTIONS
THEMA F 23 E - THEMA F SB 18 E - THEMA F SB 23 E
Note! The boiler serial number is marked on the label attached to the inside of the boiler. Refer to the 'Introduction' section page 3 for a description of the basic functions of the boiler. To safely operate the boiler, refer to the Users Instructions.

INSTALLATION SECTION

Introduction.. Page 3 Dimensions... 3 Technical data.. 4 - 5 Boiler schematic.. 6 Fixing jig... 7 Domestic hot water system design. 7 Heating system design... 8 Piping system installation.. 8 Boiler location... 9 Boiler installation.. 10 Rear outlet flue installation.. 11 - 12 Top outlet flue installation.. 13 Electrical connection... 14 Commissioning.. 15 - 16 Safety devices... 16 Settings... 17 Changing gas type.. 17

SERVICING SECTION

Routine cleaning and inspection. Page 18 - 19 Replacement of parts.. 19 - 24 Microswitch assembly... 19 Fan... 19 Air pressure switch.. 19 Spark generator... 19 Main printed circuit board.. 19 Ignition printed circuit board.. 20 Pump... 20 Temperature/Pressure gauge.. 20 Reversing valve assembly.. 20 Reversing valve front section.. 21 Loss of water switch.. 21 Water valve or diaphragm.. 21 Gas valve... 22 Modulating coil... 22 Central heating safety valve.. 23 Heat exchanger.. 23 Expansion vessel.. 23 Boiler thermistor... 23 Overheat thermostat.. 24 Combustion chamber insulation.. 24 Ignition electrode.. 24 Flame sense electrode.. 24 Burner... 24 Burner injectors.. 24 Timeclock... 24 Schematic wiring diagram.. 25 Fault finding... 26 - 27 Spare parts... 27
Mandatory warning notice for CEE countries WARNING, this appliance is designed, approved and inspected to meet the requirements of the English market. The identification plate located on the inside of the appliance certifies the origin where the product was manufactured and the country for which it is intended. If you see any exception to this rule, please contact your nearest Saunier Duval dealer. Thank you in advance for you assistance.

INTRODUCTION

The THEMA F 23 E boiler is a wall mounted modulating combination boiler with electronic ignition providing central heating and instantaneous domestic hot water. Both the central heating and domestic hot water temperature are user adjustable from the boiler control panel. Domestic hot water demand always has priority over heating demand. The THEMA F SB 18 E and SB 23 E boilers are wall mounted modulating boilers with electronic ignition providing central heating only. The central heating temperature is user adjustable from the boiler control panel. The boilers are of the II2H3+ category for use with Natural Gas (G20) as distributed in the United Kingdom, or with Butane or Propane gas (G30/G31) with the appropriate conversion kit. Conversion kits: Conversion Part No. Natural Gas (G20) to G30/GBoilers burning LPG or similar gases MUST NOT be fitted in basements or below ground level. The boiler has a fan assisted balanced flue which both discharges the products of combustion to and draws the combustion air from the outside air.

Diagram 1

The boiler is supplied for rear outlet flue connection. Alternatively, the boiler is designed to allow the flue system to be connected to the top of the boiler, top outlet flue connection. Refer to the flue fitting instructions. Electrical components have been tested to meet the equivalent requirements of BEAB. The boiler is designed for use as part of a sealed water central heating system with fully pumped circulation. The pump, expansion vessel and associated safety devices are all fitted within the boiler. The boiler can be installed against either an external wall or on an adjacent inside wall, that is, the flue system will pass directly to the rear or to either side to the terminal fitted on the outside wall face. The installation must be carried out by a competent person in accordance with the relevant requirements of The Building Regulations, The Water Byelaws, The Building Standards (Scotland) Regulations and any applicable local regulations. Ancillary equipment A range of flue accessories are available including vertical flues, twin-pipe flues, bends etc. For further information contact your supplier.

THEMA F 23 E

THEMA SB 18 E and SB 23 E

DIMENSIONS

Diagram 2
Net weight: 41 kg Gross weight : 43 kg
The boiler is delivered in three separate packages: - The boiler - The fixing jig - The flue system

Hab 271a

TECHNICAL DATA
THEMA F SB 18 E THEMA F SB 23 E 1,2,70 1,13 0,4,8 2,01 1,13 0,4,8 1,98 0,97 2,3,88 1,63 1,63 THEMA F 23 E Heating output Efficiency Heating adjustment Expansion vessel effective capacity Expansion vessel charge pressure Maximum system capacity at 75C Safety valve, maximum service pressure Products outlet diameter Fresh air inlet diameter Hot water output automatically variable from (kW) (BTU/H) to (kW) (BTU/H) (%) (l) (bar) (l) (bar) ( mm) (mm) automatically variable from (kW) (BTU/H) to (kW) (BTU/H) (C) ( l/min) (l/min) (l/min) (bar) (bar) (V) (W 8,9 30,000 23,3 80,9,0,150
8,9 8,9 8,9 30,000 30,000 30,000 23,3 18,5 23,3 80,000 63,000 80,000 91,5 90,5 91,5 38C to 90C 6,5 6,5 6,5 0,5 0,5 0,100 230 150
Maximum hot water temperature Specific flow rate (for 30C temp rise) Threshold flow rate Nominal water flow rate Maximum supply pressure Minimum operating pressure Electrical supply Maximum absorbed power

Natural Gas (G20)

Burner injector Inlet pressure Diaphragme Gas rate (maximum) Gas rate (minimum) Burner injector Inlet pressure Diaphragme Gas rate (maximum) Gas rate (minimum) Burner injector Inlet pressure Diaphragme Gas rate (maximum) Gas rate (minimum) Burner injector Inlet pressure Diaphragme Gas rate (maximum) Gas rate (minimum)
mm mbar mm m3/h m3/h mm mbar mm kg/h kg/h mm mbar mm kg/h kg/h mm mbar mm m3/h m3/h
1,2,70 1,13 0,4,8 2,01 1,13 0,4,8 1,98 0,97 2,3,88 1,63
1,2,17 1,13 0,3,2 1,62 1,13 0,3,2 1,60 0,97 2,

Town gas (G130)

Propane (G31)

Butane (G30)

Pressure table :
(kW) (Btu/h) (kW) (Btu/h)
Heat output 8,23,Heat input 11,9 13,2 14,4 15,7 16,9 18,1 19,2 20,4 21,5 22,7 23,8 24,9 26,0 26,9 28,91713 96602
2,1 5,3 6,3 2,6 6,3 7,5 3,0 7,4 8,8 3,5 8,6 10,2 4,0 9,8 11,7 4,5 11,1 13,3 5,1 12,5 14,9 5,7 13,9 17,2 6,3 15,5 20,1 6,9 17,0 20,3 7,6 18,6 22,2 8,3 20,4 24,4 8,8 21,7 26,0 9,8 24,1 28,8
G 20 G 30 G 31 (mbar) 1,3 (mbar) 3,7 (mbar) 4,0

Pump :

The performance of the pump varies according to the pump bypass setting, see diagram 3.
Available pressure (kPa) between heating flow and return

(10 kPa = 1 m WG)

Pom 052
1 Bypass fully shut 2 Open 1/4 turn 3 Open 1/2 turn 4 Open 1 turn 5 Open 2 turns
Flow rate through heating system (I/h)

Diagram 3

BOILER SCHEMATIC
24 Ignition module Heating temperature adjuster Hot water temperature adjuster Temperature/ressure gauge Expansion vessel Pump Automatic air vent Burner Heat exchanger bleed pipe Heatexchanger Gas valve Heating and hot water thermistor Ignition electrode Overheat thermostat Flame sense electrode Loss of water pressure switch Fan Air pressure switch Gas cock

A B C D E

Heating return Cold water inlet Heating flow Domestic hot water flow Gas supply
THEMA F SB 18 E - THEMA F SB 23 E
Ignition module Heating temperature adjuster Temperature/pressure gauge Expansion vessel Pump Automatic air vent Burner Heat exchanger bleed pipe Heatexchanger Gas valve Heating and hot water thermistor Ignition electrode Overheat thermostat Flame sense electrode Loss of water pressure switch Fan Air pressure switch Gas cock

Shy 131

Diagram 4

FIXING JIG

From left to right, the fixing jig comprises: A - Heating return with isolating valve (m). B - Cold water inlet with isolating valve (p). C - Heating flow with isolating valve (q), drain screw (r) and safety valve (s). D - Domestic hot water out. E - Gas service cock.

3 A B C

Filters and washers : 1 - Washer 2 - Metal filter 3 - Flow regulator 4 - Plastic filter 5, 6 & 7 - Washers

p r q s

Pla 105c
THEMA F SB 18 THEMA F SB 23 E
From left to right, the fixing jig comprises: A - Heating return with isolating valve (m). C - Heating flow with isolating valve (q), drain screw (r) and safety valve (s). 3 E - Gas service cock. 11

m p r q s 7 E

Pla 116b

Diagram 5

DOMESTIC HOT WATER SYSTEM DESIGN
Copper tubing or plastic Hep2 O may be used for the domestic hot water system. Unnecessary pressure losses should be avoided. The boiler may operate with a minimum supply pressure of 0,3 bar but under a reduced flow rate. Optimum performance will be obtained from a supply pressure of 1 bar. The flow restrictor must be fitted in the cold water inlet during installation. This limits the flow through the boiler to a maximum of 12 l/min.

HEATING SYSTEM DESIGN

The THEMA F boiler is compatible with any type of installation. Heating surfaces may consist of radiators, convectors or fan assisted convectors. Pipe sectional areas shall be determined in accordance with normal practices, using the output/pressure curve (diagram 3). The distribution system shall be calculated in accordance with the output requirements of the actual system, not the maximum output of the boiler. However, provision shall be made to ensure sufficient flow so that the temperature difference between the flow and return pipes be less than or equal to 20C. The minimum flow is 500 l/h. The piping system shall be routed so as to avoid any air pockets and facilitate permanent venting of the installation. Bleed fittings shall be provided at every high point of the system and on all radiators. The total volume of water permitted for the heating system depends, amongst other things, on the static head in the cold condition. The expansion vessel on the boiler is pressurised at 1 bar (corresponding to a static head of 5 m w.g.) and allows a maximum system volume of 140 litres for an average temperature of 75C and a maximum service pressure of 3 bar. This pressure setting can be modified at commissioning stage if the static head differs. An additional expansion vessel can be fitted to the system if required, see diagram 6. Provision shall be made for a drain valve at the lowest point of the system. Where thermostatic radiator valves are fitted, not all radiators must be fitted with this type of valve, and in particular, where the room thermostat is installed. In the case of an existing installation, it is ESSENTIAL that the system is thoroughly flushed prior to installing the new boiler using a proprietary product such as Fernox or Sentinel. Contact the product manufacturers for specific details. Filling the system Provision must be made for filling the system at low level. The use of a WRC approved filling loop is strongly recommended, connected as shown in diagram 6.

255 mini

50 mini

Diagram 7

The boiler must be installed so that the terminal is exposed to the external air. Note: Under certain weather conditions the flue may produce a plume of condensation, this is quite normal. If the terminal is fitted within 850mm of a plastic or painted gutter or 450m of painted eaves, an aluminium shield of a minimum length of 750mm should be fitted to the underside of the gutter or painted surface. Should any doubt exist as to the permissible position of the terminal, contact the Saunier Duval Technical Helpline 01773 828400. Cupboard or compartment ventilation The boiler can be fitted in a cupboard or compartment without need for permanent ventilation.
Minimum dimensions (in mm) for the positioning of flue terminals
A - Under a window.. 300 B - Under an air vent.. 300 C - Under a gutter.. 75 D - Under a balcony.. 300 E - From an adjacent window.. 300 F - From an adjacent air vent.. 300 G - From vertical drain pipes or soil pipes. 75 H - From an external corner of the building.. 300 I - From an internal corner of the building. 300 L - From the ground or from another floor. 300 M - Between two terminals vertically.. 1500 N - Between two terminals horizontally. 300

G C E F M

A B D I H L

Diagram. 8

Ven 060b

Ins 012a

BOILER INSTALLATION
Statutory requirements The installation of this boiler must be carried out by a competent person in accordance with the relevant requirements of the current issue of: The Gas Safety (Installation and Use) Regulations The Building Regulations The local water company Byelaws The Building Standards Regulations (Scotland) The Health and Safety at Work Act Sheet metal parts WARNING. When installing or servicing this boiler, care should be taken when handling the edges of sheet metal parts to avoid the possibility of personal injury. Installing the boiler Prior to starting work, the system must be thoroughly flushed so as to eliminate any foreign bodies and contaminants such as filings, solder particles, oil, grease etc. Note. Solvent products could cause damage to the system. Note. If using a rear outlet flue system, follow the instructions in 'Rear outlet flue installation' section prior to hanging the boiler. Engage boiler upper part onto the hook, see diagram 9. Allow the boiler to seat down onto support plate, see diagram 10. Fit filter and washers, strictly adhering to the sequential order and directions shown on diagram 5. Connect the various couplings between the boiler and the connection plate.

Diagram 12

Diagram 13
Table 1 Flue cutting lengths
Cutting length (mm) Flue option Rear outlet Side flue to left (Diagram 13) Rear outlet Side flue to right (Diagram 14) outer pipe e + a + 96 inner pipe e + a + 173 Comments maximum distance 'X' without extension 1080 mm maximum distance 'x' without extension 1080 mm

e + a + 154

e + a +231

Hab 209

Diagram 14

Hab 208

Extended flue The horizontal flue is extended by using one or more of the 1000 mm extension pipes, Saunier Duval part number 85091. These are connected together by push fit type joints, clamps and seals. Calculation of flue cutting lengths for extended flue Using the correct number of extension kits as table 2, measure dimensions a and e, see diagram 13 or 14. Cut both the inner and outer pipe to the dimensions given in table 3. Important: All cutting lengths should be measured from the push fit end of the extension pipe. Do not leave any burrs or sharp edges on the cut ends of the pipes. Installation of flue assembly-direct rear flue Fit rubber sealing collar (C) into groove at the outer end of pipe (A), see diagram 16. Fit outer pipe (A) into wall with groove to the outside. Pull pipe inwards to bring rubber sealing collar hard up against external wall, see diagram16. Fit internal plastic flange (F) onto outer pipe. Push along the pipe until engaged against internal wall. From inside, insert inner pipe (B) into outer pipe turning anti-clockwise to allow inner to fully enter outer pipe. Fit rubber sleeve (H) onto outer pipe. Take hold of inner flue,twist clockwise and push gently onto fan outlet. Pull rubber sleeve onto boiler spigot ensuring a good seal. Installation of flue assembly-side flue Fit rubber sealing collar (C) into groove at the outer end of pipe (A), see diagram 16. Fit outer pipe (A) into wall with groove to the outside. Pull pipe inwards to bring rubber sealing collar hard up against external wall, see diagram16. Fit internal plastic flange (F) onto outer pipe. Push along the pipe until engaged against internal wall. From inside, push inner pipe (B) into outer pipe turning anti-clockwise to allow inner to fully enter outer pipe. Fit rubber sleeve (H) onto outer pipe. Fit both 'O' rings (F) into flue elbow (D), one at the inlet, one at the outlet. By necessity, they are a loose fit, apply a small amount of silicone grease to each 'O' ring when fitting. Important: If the flue has been cut, ensure that there are no burrs that could damage the 'O' ring. Remove the backing from the self adhesive gasket (J) and carefully fit gasket to base of flue elbow. Fit elbow onto boiler and secure with the four screws (G). Take hold of inner flue, twist clockwise and push gently onto the elbow outlet taking care not to tear the 'O' ring. Pull rubber sleeve onto elbow ensuring a good seal.

When fitting room thermostat, remove wire link (E) and connect voltage free thermostat as shown
For no external controls leave wire link (E) in place

sch 228

The mains electrical cable is supplied with the boiler. It is coiled and tucked inside the boiler

Cylinder

THEMA F SB 18 E THEMA F SB 23 E

Diagram 19

sch 227

sch 229

COMMISSIONING
The commissioning and first firing of the boiler must only be done by a competent person. Gas installation It is recommended that any air is purged from the supply at the gas inlet test point on the left hand side of the gas valve, see diagram 20. Filling the system

Diagram 20

Open shut off valves (slot of screw corresponds to flow direction).
Undo, but do not remove, cap on automatic air vent on top of pump. Do not retighten cap.
Open the tap on the system filling loop and fill the system until the pressure indicated on the display is between 1 and 2 bar.

Ins 017a

Reg 007
Important: - If this procedure is not carried out properly, the boiler will go into safety lock-out until all of the air has been purged. - When venting air from boiler, do not touch the schrader valve on the expansion vessel, it is NOT a vent. - Before starting the boiler, turn the pump impellor to make sure it is free to move. Unscrew black cap on front of pump. Using screwdriver, push in pump spindle and turn pump impellor 3 to 4 times. DO NOT HIT SPINDLE. Replace black cap. Starting the boiler Before starting the boiler check that: - The gas meter tap is open. If using Butane or Propane, check that valve on storage cylinder or tank is open. - you have removed the two fan transist clips from fan.
- The boiler gas service cock is open. - The boiler is connected to the electrical supply and switched on. - The front casing is fitted. First starting up Following the instructions given in the 'User Instructions' set boiler to run in central heating mode. Set boiler thermostat for maximum temperature and check that any external controls, if fitted, are calling for heat. Allow the temperature to rise to the maximum value, with all radiator valves open. The temperature rise will cause release of the gases contained in the water of central heating system. - Gases driven towards the boiler will be automatically released through the automatic air vents. - Gases trapped at the highest point of the system must be released by bleeding the radiators.

Sec 055

Ins 061

Ins 062

Bleed air from the heat exchanger by undoing the air bleed cap. Do not remove this cap. When all the air has been removed, tighten cap.
Bleed each radia tor until a continuous jet of water is obtained.
Open various hot water taps to bleed system.
Make sure that pressure gauge reads between 1 and 2 bar. Re-pressurise system as necessary.

Reg 008

mec 117
On reaching maximum temperature, the boiler should be turned off and the system drained as rapidly as possible whilst still hot. Refill system to a pressure of 1 bar and vent as before. Restart boiler and operate until a maximum temperature is reached. Shut down boiler and vent heating system. If necessary, top up heating system and make sure that a pressure of 1 bar is indicated on the pressure gauge when system is COLD. Gas pressures The main burner pressure should be checked during commissioning to make sure the correct input is obtained. Proceed as follows: Shut down boiler. Undo screw on burner pressure test point below sealed combustion chamber, see diagram 23. Connect a suitable pressure gauge. Gain access to the rear of the control panel and locate the range rating adjuster screw, see diagram 24. Start boiler as described in 'User Instructions'. Set boiler thermostat to maximum and check that any external controls are calling for heat. Check that the reading on the gauge matches that given in 'Technical Data' for the type of gas being used. Adjust the range rating adjuster screw as necessary to obtain the desired input. Shut down boiler. Remove pressure gauge, tighten up test point screws and check for gas soundness. Using a ball point pen, clearly indicate on the data label the input the boiler is set to. Note: This adjustment does not affect the domestic hot water output. If measured burner pressure differs greatly from the given figure, check the gas inlet pressure as follows: Shut down boiler.

Diagram 23

Diagram 24
Remove screw from inlet test point on the side of the gas valve, see diagram 23. Connect a suitable pressure gauge. Start boiler as described in 'User Instructions'. Check that the inlet pressure reading matches that given in 'Technical Data' for the type of gas being used. Shut down boiler. Remove pressure gauge, tighten up test point screws and check for gas soundness. If the gas pressure is incorrect, refer to the Fault Finding section in 'Servicing Instructions'. If the inlet pressure is below that given, the gas supply pipework/meter must be checked and any fault corrected. In the case of an LPG installation, check the storage tank or cylinder, regulator and pipework.

SAFETY DEVICES

Air flow rate safety device If an obstruction, even partial, of the flue occurs, for any reason whatsoever, the built in safety system of the boiler will turn the boiler OFF and the fan will continue to run. The boiler will be ready to operate when the fault has been cleared. In case of power supply failure The boiler no longer operates. As soon as power supply is restored, the boiler will be automatically restarted. Overheat safety In the event of a problem, the overheat thermostat causes safety shutdown of the boiler. Should this occur, reset the thermostat by pressing in the red button. The overheat thermostat is located on the RHS of the heat exchanger. Important notice: A central heating system cannot operate satisfactorily unless it is properly filled with water and unless the air initially contained in the piping systems has been properly bled off. If these conditions are not satisfied, air noise will occur within the system. The THEMA F 23 E boiler has a built in frost protection device that protects the boiler from freezing. If the boiler is to be left and there is a risk of frost, ensure that the gas and electrical supplies are left connected and the summer/winter switch is in the position. The frost protection device will light the boiler when the temperature of the boiler water falls below 6C. When the temperature reaches 16C, the boiler stops. Note: This device works irrespective of any room thermostat setting and only protects the boiler.

REPLACEMENT OF PARTS

To replace microswitch assembly exept SB models) Disconnect microswitch by pulling off plug. Unclip external controls connector from mounting bracket. Undo two screws securing microswitch assembly to reversing valve assembly, see diagram 29. Remove microswitch assembly from reversing valve. Fit replacement microswitch assembly in reverse order to removal. Reconnect plug and refit external controls connection to bracket. To replace fan Disconnect power supply and earth leads to fan. Unscrew and remove two fan retaining screws located at front edge of fan mounting plate. Remove fan with mounting plate attached by pulling forwards and out of boiler. Unscrew and remove three screws securing fan to fan mounting plate. Fit replacement fan to mounting plate and secure with screws. Fit replacement fan to boiler in reverse order to removal making sure that mounting plate retaining lugs are properly engaged into flue hood. Reconnect power supply and earth leads. Important: Make sure that fan outlet is correctly fitted into either the flue elbow for top outlet flue, or the rear connector for rear outlet flue. Before commissioning boiler, remove the two plastic transit clips from replacement fan. To replace air pressure switch Locate air pressure switch in upper left hand corner of sealed chamber. Pull off plastic tube from left hand connection. Grasp pressure switch and disengage it from bracket clips by pulling from the top. Remove electrical connections from switch. Fit electrical connections to terminals 1 and 3 of replacement switch. Fit replacement switch in reverse order to removal. Important: Refit plastic tube to LEFT hand connector (marked P1). To replace spark generator Locate spark generator on bracket to right hand side of gas valve. Undo and remove screw securing lower terminal cover to bracket and remove bracket. Disconnect four leads from spark generator.
microswitch on THEMA F 23 E

Diagram 29

Diagram 30
Undo and remove screw securing spark generator to bracket and remove spark generator. Fit replacement spark generator in reverse order to removal. Reconnect two grey power supply leads and two clear ignition leads to spark generator, the polarity is not important. Refit lower terminal cover. To replace main printed circuit board (PCB) With lower front panel down as described previously, undo and remove screw holding pump connection cover to PCB cover, see diagram 30. Open cover and unclip plastic clip securing pump cable to lower front panel. Pull off pump connector and earth lead. Undo and remove four screws securing PCB cover to lower front panel. Lift off PCB cover. Pull off connectors CN6, CN7, CN8 and CN9 on PCB. Undo and remove screw holding PCB to lower front panel. Lifting PCB up slightly on LHS, pull PCB out of electrical connector on ignition PCB. Leave ignition PCB in place.

Hab 286

Sch 228
Fit replacement PCB in reverse order to removal. Important: When fitting replacement PCB, ensure that control knob spindles correctly locate into PCB adjuster slots. Refit connectors and covers in reverse order to removal. To replace ignition PCB Gain access to PCB's as described in previous section. Remove main PCB securing screw as described in previous section. Pull off three electrical connectors on PCB. Lift up ignition PCB, separate from main PCB and remove from boiler. Fit replacement PCB in reverse order to removal. Refit connectors and covers in reverse order to removal. To replace pump Drain down heating circuit of boiler only as follows: Close isolating valves on flow and return connections on fixing jig, see diagram 5. Note: These valves are closed when slots are at right angles to direction of flow. It is not necessary to drain entire heating circuit to carry out this work. Drain boiler by attaching a plastic tube to drain outlet and opening drain valve knob anticlockwise, see diagram 5. Gain access to pump connection as described in 'To replace main PCB'. Pull off pump connector and earth lead. Pull out retaining clip from telescopic pump outlet connection and slide connection upwards to release from pump. Undo and remove two fixing screws and remove pump retaining bracket from front of pump. Grasp pump body, lift upward to disengage from reversing valve and turn pump to right. Remove pump by pulling forward and over reversing valve assembly. Discard old pump inlet 'O' ring. Apply silicone grease to new 'O' ring supplied, and fit onto inlet connection on replacement pump. Fit replacement pump in reverse order to removal. Note: Apply silicone grease to pump outlet connection 'O' ring before assembly. Refit pump electrical connection. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace temperature/pressure gauge Drain down heating circuit of boiler only as described in 'To replace pump'. Undo and remove screw securing pressure gauge capillary to front section, see diagram 31. Carefully pull capillary from front section. Undo and remove two screws securing temperature/pressure gauge to lower front panel and remove gauge. Fit replacement gauge in reverse order to removal.

Diagram 31

Diagram 32

Fit capillary of new gauge to front section using new 'O' ring supplied. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace reversing valve assembly Remove temperature/pressure gauge capillary as described previously. Remove pump as described previously. Remove microswitch assembly as described previously. Remove retaining clip from LHS pipe connection on front section of valve and disengage pipe. Unscrew and disconnect heating flow (centre) connection at fixing jig. Remove retaining clip from heating flow pipe connection on right of front section. Remove flow pipe from boiler. Unscrew and disconnect heating return (left hand) connection at fixing jig. Remove retaining clip from expansion vessel pipe connection at rear of reversing valve assembly and disengage pipe, pushing pipe back and out of reversing valve. Undo and remove large screw holding water valve to back plate of reversing valve assembly, see diagram 32.

Des 054

Cla 007
Push water valve back to disengage it from reversing valve. Unclip and remove loss of water pressure switch from left of reversing valve assembly, see diagram 33. From below boiler, undo and remove three screws holding reversing valve to bottom plate of boiler. Remove complete reversing valve assembly from boiler. Undo and remove heating return connecting pipe and hose from rear of reversing valve assembly. Fit hose to replacement reversing valve assembly. Fit replacement reversing valve into boiler in reverse order to removal. Note: Use new 'O' rings, retaining clip, filter and washer provided. Unscrew and remove microswitch assembly from top of replacement reversing valve assembly to allow refitting of water valve. Note: fit expansion vessel pipe and loss of water switch to reversing valve assembly before pump, to ensure that it is correctly located. Apply silicone grease to all 'O' rings and hoses prior to assembly. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace reversing valve front section Remove pressure gauge capillary as described previously. Remove pipe connections from either side of reversing valve front section, refer to previous section. Move short selector lever on front of valve to left hand position. From below boiler, undo and remove single screw holding reversing valve front plate to bottom plate of boiler. Undo and remove six screws holding front section to rear section of reversing valve, see diagram 34. Remove front plate complete with pump bracket and then front section from reversing valve, along with rubber sealing gasket. Assemble bypass valve provided and fit into hole in underside of replacement front section. Fit 'U' shaped retaining clip. Note: Use bypass valve fitted to original front section for guidance. Fit replacement front section, with gasket, to rear section. Locate front plate and replace six fixing screws. Take care to evenly tighten screws ensuring they are not cross threaded. Refit pipe connections to either side of front section using new 'O' rings provided. Apply silicone grease to 'O' rings before fitting. Refit pressure gauge capillary in reverse order to removal. Ensure short selector lever on front of valve is set to right hand position. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks.

Diagram 37

Unclip thermistor from pipe. Pull off electrical cennections from thermistor. Fit replacement thermistor in reverse order to removal. Note: No heat sink compound is required. The polarity of the connections is not important. To replace overheat thermostat Locate the overheat thermostat on the right hand side of the heat exchanger. Pull off the electrical connections from the thermostat. Unscrew and remove two screws holding thermostat to heat exchanger. Fit replacement thermostat in reverse order to removal, using heat sink compound on the contact surface of thermostat. Refit electrical leads, the polarity is not important. To replace combustion chamber insulation Front section Remove combustion chamber from boiler as described in 'Routine Cleaning and Inspection'. Slide side panels out of combustion chamber sides. Lift front insulation panel free from retaining lugs and away from cover. Fit replacement panels in reverse order to removal. Rear panel Remove burner from boiler as described in 'Routine Cleaning and Inspection'. Remove clip from base of insulation panel. Pull bottom edge of insulation panel forward, downward and out from behind heat exchanger. Fit replacement panel in reverse order to removal. Replace burner into boiler in reverse order to removal. To replace ignition electrode Remove combustion chamber from boiler as described in 'Routine Cleaning and Inspection'. Pull off ignition leads from ignition electrode. Unscrew and remove two screws holding ignition electrode onto burner. Fit replacement ignition electrode in reverse order to removal. Refit ignition leads, the polarity is not important. To replace flame sense electrode Remove combustion chamber from boiler as described in 'Routine Cleaning and Inspection'. Pull off lead from flame sense electrode. Unscrew and remove screw holding earth lead to flame sense electrode. Unscrew and remove screw holding flame sense electrode onto burner. Fit replacement flame sense electrode in reverse order to removal. Refit lead. To replace burner Pull off ignition and flame sense leads from electrodes. Remove burner from boiler as described in 'Routine Cleaning and Inspection'. Remove ignition and flame sense electrodes as described in previous sections. Unscrew and remove two screws holding burner injector bar to burner and remove injector bar. Asemble replacement burner, supplied in parts, as follows: Fit burner injectors to injector bar and tighten. Assemble burner elements (14) into front and rear burner supports with securing pins and rods, using original burner for guidance. Fit burner injector bar to burner. Fit ignition and flame sense electrodes to burner. Fit replacement burner to boiler in reverse order to removal. Reconnect ignition and flame sense leads to electrodes. Reconnect earth lead to flame sense electrode. The polarity of the ignition leads is not important. To replace burner injectors Remove burner as described previously. Remove ignition and flame sense electrodes as described in previous sections. Unscrew and remove two screws holding burner injector bar to burner and remove injector bar. Unscrew and remove burner injectors from burner bar. Fit replacement injectors to injector bar and tighten. Note: make sure that injector size, marked on each injector, is the same as that given in 'Technical Data'. Reassemble burner and replace into boiler in reverse order to removal. To replace timeclock Gain access to rear of lower control panel as described in 'Routine Cleaning and Inspection'. Unscrew and remove two screws holding timeclock to lower control panel. Remove PCB cover. Remove timeclock plug from connection CN7 on main PCB. Fit replacement timeclock in reverse order to removal.

SCHEMATIC WIRING DIAGRAM

IG P SW3 K4 K5 EV1 TA CTN EV AL FA FL TRA Pr EX ON/OFF switch Pump Microswitch Hight limit thermostat Loss of water switch Gas valve modulating coil Room thermostat (if fitted) Boiler thermistor Gas valve Ignition unit Ignition electrode Flame sense electrode Transformer Air pressure switch Fan

THEMA F 23 E PCB

6.13 6.14

6.15 6.11

6.12 6.9

6.8 6.6 6.4 6.2

2.2 14.6 2.1 9.1 9.2 8.4 8.3 8.2 8.1 14.4 14.3 14.7 14.2 14.1 14.5
13.4 13.1 12.2 13.3 12.1 13.2
THEMA F SB 18 E and THEMA F SB 23 E PCB

Ra TH K5

6.12 6.9 6.8 6.6 6.4 6.2
IG P K4 K5 EV1 TA CTN EV AL FA FL TRA Pr EX TH
ON/OFF switch Pump Hight limit thermostat Loss of water switch Gas valve modulating coil Room thermostat (if fitted) Boiler thermistor Gas valve Ignition unit Ignition electrode Flame sense electrode Transformer Air pressure switch Fan Cylinder thermostat

3.3 3.2 3.1

13.4 13.1 12.2 12.1 13.2 13.3

Diagram 39

Sch 240

Sch 242

Diagram 38

FAULT FINDING

Prior to fault finding, check : Inlet gas pressure = 20 mbar Electrical supply = 240 V - 50 Hz Central heating system is pressurised at 1 - 1,5 bar. Overheat thermostat on RHS of heat exchanger has not tripped reset if necessary. Carry out electrical system checks i.e. earth continuity, resistance to earth, short circuit and polarity with a suitable meter. Note : these must be repeated after any servicing or fault finding. Ensure that all external controls are correctly wired and calling for heat. The fault finding charts will enable the majority of faults to be diagnosed. To use the charts effectively, it is necessary to determine exactly which aspects of the boiler are working correctly and which are not. For example: If the domestic hot water works but the heating doesnt, refer to chart No. 1. If heating works correctly but the hot water doesnt, refer to chart No. 2. IMPORTANT: Always adopt a logical, step by step procedure starting at the beginning of the appropriate fault finding chart. WARNING. Always isolate the boiler from the electrical supply before carrying out any electrical replacement work. Always check for gas soundness after any service work.

NO CENTRAL HEATING

Turn ch temp. control to max. does burner fire ?

Does pump run ?

Refer to chart n3

Does fan run ?

Refer to chart n4
Is short selector lever on front of reversing valve in right hand position ?
Does burner fire when a hot tap is opened ?

NO YES

Refer to chart n2
External controls (if fitted)

Internal control (clock)

Short out external controls connection on top of reversing valve. Does burner fire ?
Rectify wiring operation faults on external controls
Is there continuity across terminals 3 and 4 of clock ?
Remove leaos from boiler thermistor. Check its resistance according to thermistor value table. is thermistor ok ?
Is clock calling for heat ? Replace thermistor
Is wiring between clock and pcb connection cn7 ok ?

Replace clock

Replace main pcb

CHART 1

Open hot tap fully. Does burner fire ?

NO HOT WATER

(except SB models)

PUMP NOT RUNNING

Is there 240 v at pump ?

YES YES

With selector switch/thermostat NO in position and turner to maximum. Does burner fire for CH ? Refer to chart n2

Is pump jammed ?

Is there 240 v at terminal cn2 of PCB ?

Replace pump motor

Free pump
Is there at least 3 litres/min water flow at tap ?
Check mains water supply, water filter

Replace main PCB

Check operation of water valve diaphragm. Does reversing valve mechanism move when hot tap is opened ?

Replace diaphragm

CHART 3
Is there continuity across DHW microswitch and PCB connections cn 6.4 and cn 6.9 ?

Replace dhw microswitch

FAN NOT RUNNING
Is there 240 v at fan ? Is fan jammed ?
Remove leads from boiler thermistor. Check its resistance in accordance with thermistor value table. Is thermistor ok ?

Replace thermistor

Replace fan

CHART 4

CHART 2

Termistor Values

Temperature (C) nominal resistance () for NTC Temperature (C) nominal resistance () for NTC 50 3605

SPARE PARTS

When ordering spare parts, quote the part number and description, stating the appliance model number and serial number from the data badge. Short parts list No. Description Fan Pump Spark generator Air pressure switch Main PCB (SB models) Main PCB (THEMA F 23 E) Part No. No. Description Part No. Control PCB (all models) 57277 Water valve diaphragm kit 52519 Microswitch assembly (THEMA F 23 E)51590 Temperature/pressure gauge 57278 Boiler Thermistor 57060 Overheat thermostat 51199