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.

Diagram. 10

Diagram. 9
REAR OUTLET FLUE INSTALLATION
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. For top outlet flue connection, refer to 'Top outlet flue installation' Rear outlet flue - kit 86151 The rear outlet flue system consists of two parts, a white painted outer pipe and an aluminium inner, they are positively locked together when assembled. The flue kit 86151, see diagram 11, is 1000 mm long and comprises: - Outer pipe... A - Inner pipe... B - External rubber sealing collar.. C - Flue elbow.. D - Internal flange.. E - 'O' rings... F - Screws.. G - Rubber collar.. H - Clamp and seal..I - Gasket.. J

Ins 020

A - Direct rear outlet flue Mark correct position of hole from template using hole between hook and connecting plate.

Pho 422

Diagram 11

Ins 021

B - Rear outlet side flue Mark the horizontal centre line on the rear wall. Extend the horizontal centre line to the side wall and mark the vertical centre line of the flue hole as shown in diagram 12. Important: When cutting the flue hole and when extending the flue centre line to a side wall, remember that the flue system must have a fall of about 35 mm per metre of flue DOWNWARD AWAY FROM the boiler. There must NEVER be a downward incline towards the boiler. Cutting the flue hole Making allowance for the slope of the flue, cut hole in external wall, preferably using a core drill. For installations with internal and external access Use a 105 mm diameter core drill. For installations with internal access only - Use a 125 mm diameter core drill. Important: Before cutting the hole for flues to the rear of boiler, always cover fixing jig to make sure it is not damaged. Calculation of flue cutting lengths Measure wall thickness e (mm). For side flues, measure distance from inside face of side wall to centre line of flue and subtract 176 mm for right hand flue or subtract 234 for left hand flue to get dimension a (mm), see diagram 13 or 14. Refer to table 1 for cutting lengths of both inner and outer flue pipes for each of the various flue options available. Important: All flue cutting lengths must be measured from the terminal end of the flue pipes, see diagram 15. When the dimension X measured on site is greater than that given in table 1, a flue extension kit will be required, refer to table 2 for details. Refer to table 1 for the cutting lengths of both the inner and outer pipes for each of the flue options available.

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.

Table 1 :

Flue Cutting length (mm) Flue option outer pipe inner pipe e + a + 202 Comments maximum distance 'X' without extension 1080 mm Flue option outer pipe inner pipe e + a + 800 Comments maximum distance 'X' without extension 1080 mm Top outlet e + a + 877 Side flue to (left or right)

Diagram 17

Diagram 18
Table 2 : Number of extension kits required Flue option Dimension 'X'
Side flue (left or right) 1081 to 1811 mm 1812 to 2542 mm No. of extension kits 1 2

Table 3 :

Extended Flue Cutting length (mm)
Top outlet e + a + 125 Side flue to (left or right)
Calculation of flue cutting lengths Measure wall thickness e (mm), see diagram 17. For side flues, measure distance from inside face of side wall to centre line of flue and subtract 205 mm for both right and left hand flues to get dimension a (mm). Refer to table 1 for cutting lengths of both inner and outer flue pipes for each of the various flue options available. Important: All flue cutting lengths must be measured from the terminal end of the flue pipes, see diag. 15. When the dimension X measured on site is greater than that given in table 1, a flue extension kit will be required, refer to table 2 for details. 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 3, measure dimensions a and e, see diagram 17. 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 Fit rubber sealing collar (C) into groove at the outer end of pipe (A), see diagram 18. Fit outer pipe (A) into wall with the groove to the outside. Pull pipe inwards to bring rubber sealing collar hard up against external wall, see diagram16. Fit internal plastic flange (E) onto outer pipe. Push along the pipe until engaged against internal wall. From inside, insert inner pipe (B) into outer pipe. Fit both 'O' rings (F) into the 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. Fit clamp and seal (I) onto outer pipe ensuring a good seal.

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

Diagram. 27

Reg 055 Mec 121

Diagram. 26

ON DIP

CHANGING GAS TYPE

Should it become necessary to change the gas type, a modification kit will be required. This modification must only be carried out by a suitably qualified engineer. Conversion: Natural Gas (G20) to G30/G31 Part No. 86161

Reg 013

ROUTINE CLEANING AND INSPECTION
To ensure the continued efficient and safe operation of the boiler it is recommended that it is checked and serviced at regular intervals. The frequency of servicing will depend upon the particular installation conditions and usage, but in general once a year should be enough. It is the law that any servicing is carried out by a competent person. Service Check and Preparation. Operate boiler and check for any faults that need to be put right. Isolate boiler from the gas and electrical supplies. On completion check all gas carrying parts for soundness with leak detection fluid. The maximum domestic hot water flow rate is 12 litres/minute. Remove boiler casing as follows: Upper front panel Hinge down control cover to gain access to control panel. Disengage the two 'quarter turn' fasteners by turning the heads of the screws a quarter of a turn towards the centre of the boiler. Carefully lower the panel down on its hinge until it is horizontal. Turn both plastic catches to release upper front panel. Remove upper front panel by pulling forward at the bottom and lifting off. Note: The upper front panel is retained by a plastic safety strap, disengage this before removal. Side panels From below boiler, unscrew and remove black plastic screws securing side panels to the boiler. Prise out black plastic inserts and lift panel off boiler. Combustion chamber Loosen two wing nuts on combustion chamber cover. Disengage retaining lugs from holes in either side of combustion chamber and move rods away to clear combustion chamber sides, see diagram 28. Unclip two toggle clips holding upper part of combustion chamber in place. Holding both sides, pull chamber forward to release it from underside of heat exchanger and out of boiler. Take care not to damage insulation material on inside faces of combustion chamber. Cleaning the burner Pull off leads to ignition electrode. Pull off lead to flame sense electrode. Unscrew and remove screw holding earth lead to flame sense electrode. Undo main gas supply nut from main burner. Unscrew and remove locking nut from both main gas connection and burner pressure tapping point. Lift front edge of burner until tapping point and gas supply connection are free. Remove burner

Diagram 28

from boiler taking care to retain both fibre washers and seal on gas supply for use on reassembly. Unscrew and remove two injector bar retaining screws and separate injector bar from burner. Examine and clean injectors as necessary. Note: Do not use a wire or sharp instrument on the holes. Replace burner in reverse order to removal. Heat exchanger After removal of burner, examine heat exchanger for any blockages or build up of deposits. Clean using soft brush or vacuum cleaner. Important: Take care not to scratch or otherwise damage painted surface of heat exchanger. Reassembly of parts removed for servicing Replace all parts in reverse order to removal. Flue system Check externally to make sure flue is not blocked. Inspect flue system to make sure all fittings are secure. Operation of fan Switch on electrical supply and turn on gas. Switch boiler On/Off switch to 1 (On). Light burner by opening a hot tap. Without upper front panel in place, burner should be prevented from lighting by air flow detection system. Refit upper front panel. Check that fan runs when burner is lit and stops when it goes out. Cold water inlet filter (exept SB models) Drain down hot water circuit of boiler as follows: Close isolating valve on cold water inlet connection on fixing jig, see diagram 5. Open one or more hot water taps to drain boiler. Undo connecting nut from cold water inlet connection to gain access to filter. Remove white filter from inlet connection.

Des 047

Note: Connecting pipework is telescopic, it may be necessary to slide sleeve back for easier access to filter. Clean and inspect filter, replace if necessary. With both flow restrictor and filter in place, reconnect pipe to inlet connection and tighten. Fully open isolating cock on cold water inlet connection and check for leaks. Operation of water valve (exept SB models) With the Summer/Winter control in the 'Summer' position, slowly open a convenient tap until boiler lights. Measure water flow, it should not be greater than 3,5 litres/minute. If necessary, replace diaphragm. Replace all outer panels.

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.

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 33

Diagram 34
To replace loss of water switch Drain down heating circuit of boiler only as described in 'To replace pump'. Note: It is not necessary to drain entire heating circuit to carry out this work. Pinch plastic cover to release retaing clips and remove cover from switch. Pull plug lead from switch terminals. Remove clip holding switch into left side of reversing valve assembly. Pull switch out of reversing valve assembly, see diagram 33. Fit replacement switch in reverse order to removal, using new 'O' ring provided and applying silicone grease to 'O' ring before fitting. Reconnect plug to switch terminals. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace water valve or diaphragm (except SB models) Drain down hot water circuit of boiler only as described in 'Routine Cleaning and Inspection'. Remove microswitch assembly as described previously. Unscrew connecting nut from cold water inlet connection, second from left on fixing jig. Keep filter and flow regulator. Remove clip holding connecting pipe in rear of water valve. From below boiler, grip clip with long nosed pliers and pull down. Note: This connecting pipe is telescopic, it may be necessary to slide back brass sleeve to facilitate removal.

Sec 059

Remove clip holding pipe to heat exchanger in rear of water valve. From front of boiler, grip clip with long nosed pliers and pull upwards. Unscrew and remove large screw holding water valve to back plate of reversing valve assembly, see diagram 32. Disengage water valve from reversing valve and remove from boiler. Note: When disengaging water valve from heat exchanger pipe, check that non-return valve is not held on end of pipe. If so, carefully separate pipe from valve to ensure that small spring and plunger do not fly out and are lost. To replace diaphragm, undo five screws and separate main components of water valve. If white diaphragm cover is to be replaced, separate original from water valve end casting and fit replacement cover. Fit replacement diaphragm , making sure that metal disc FACES diaphragm cover and beaded edge of diaphragm is correctly fitted in corresponding groove in both cover and plastic housing, see diagram 35. Reassemble water valve, evenly tightening five screws. Fit water valve actuating pin into hole in diaphragm cover, through nose end of valve and and push in until flush, or slightly below, nose end of valve. Note: Apply silicone grease to pin before fitting. Refit water valve to boiler, locating nose end into rear of reversing valve assembly, 'springing' heat exchanger pipe to gain clearance as necessary. Fit large water valve retaining screw but do not tighten fully at this stage. Apply silicone grease to 'O' ring and fit onto end of heat exchanger pipe. Fit pipe into water valve by pulling it forward. Make sure that 'O' ring is correctly located. Whilst holding pipe in rear of water valve, fit retaining clip. This should easily clip over pipe and should NOT have to be forced. If resistance is experienced, either pipe is not correctly fitted in rear of water valve or clip is not being fitted properly through slot between back plate and plastic housing of water valve. When clip is fitted, check connection by pushing pipe back away from water valve. Refit telescopic connecting pipe to inlet of water valve after applying silicone grease to 'O' ring. Fit retaining clip into groove on connecting pipe, through slot between back plate and water valve plastic housing. Check connection by pulling pipe. Make sure that clip is not loose and likely to fall out at a later date. If in doubt, fit a new clip. With both flow regulator and and plastic filter washer in place, refit connecting nut to inlet connection and tighten. Open isolating valve on cold water inlet connection and check for leaks. Replace microswitch assembly. To replace gas valve Ensure gas supply is off. Disconnect two black electrical leads from gas valve modulating coil.

Diagram 35

Diagram 36
Disconnect two white and one red lead from gas valve main solenoid. Pull off clear plastic tube from gas valve to sealed chamber tapping point. Unscrew main gas supply pipe nut on top of gas valve, releasing spark ignition unit bracket, see diagram 36. From below boiler, unscrew gas valve connection between gas valve and fixing jig isolating cock. Unscrew and remove two screws securing gas valve to bottom plate of boiler. Remove gas valve from boiler. Refit replacement gas valve in reverse order to removal. Note: Use new 'O' ring provided between gas valve and burner supply pipe. Refit electrical connections to replacement gas valve as follows: - BLACK leads to modulating coil. - WHITE leads to EV1 and EV2 terminals of main solenoid - RED lead to COM terminal of main solenoid. To replace modulating coil Ensure gas supply is off. Disconnect two black electrical leads from gas valve modulating coil. Unscrew and remove two screws holding modulating coil to gas valve and remove coil from gas valve. Fit replacement modulating coil in recerse order to removal. Reconnect electrical leads to replacement coil. Note: All boilers are tested and factory set during manufacture. Should it be necessary to reset a gas valve, for example after replacement, refer to 'Settings'.

Mec 117

Des 058
To replace safety valve Drain down entire heating system. From below boiler, disconnect heating flow pipe from rear of fixing jig. Undo heating flow connection on front of fixing jig. Remove clip from heating flow pipe connection on right of front section of reversing valve. Pull pipe towards right and out of reversing valve. Remove pipe from boiler and keep. From below boiler, disconnect safety valve discharge pipe. Working through boiler from the front using a long screwdriver, undo and remove screw holding safety valve assembly to fixing jig. Remove complete safety valve assembly from fixing jig and remove from boiler. Fit replacement safety valve in reverse order to removal. Note: Apply silicone grease to 'O' ring before fixing pipe into right hand side of reversing valve. Refill heating system and boiler, vent and pressurise as described previously. To replace heat exchanger Drain down both heating and hot water circuits of boiler only as described previously. Note: It is not necessary to drain entire heating system to carry out this work. Remove combustion chamber cover as described in 'Routine Cleaning and Inspection'. Remove two clips from heating connections to left side of heat exchanger. Remove clip holding pump outlet connection into pump and slide connection up pump outlet pipe. Pull complete pipe down to disengage from heat exchanger. Remove retaining clip from LHS pipe connection on front section of valve and disengage pipe. Disengage pipe downwards from heat exchanger. Unscrew and disconnect two hot water connections to right side of heat exchanger. Grasp both sides of heat exchanger and slide forwards and out of boiler. Fit replacement heat exchanger in reverse order to removal. Note: Use new sealing washers and 'O' rings provided. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace expansion vessel 1 Boiler in place Note: The expansion vessel can be replaced with the boiler in place provided that there is a minimum clearance of 400mm on one side of the boiler and that no vertical pipework passes between boiler and wall on that side. Drain down the heating circuit of the boiler only as described in 'To replace pump'. Note: It is not necessary to drain entire heating system to carry out this work. Remove pump from boiler as described previously. Unscrew pipe connection nut from expansion vessel and disengage pipe from connection. Keep sealing washer. Whilst supporting weight of vessel, push bottom of vessel away from boiler, disengaging threaded connection from hole in rear of boiler. Allow vessel to drop out of its two upper retaining brackets. Remove vessel to side of boiler. Fit replacement expansion vessel in reverse order to removal ensuring that sealing washer is fitted to vessel pipe connection. Check that vessel charge pressure is 1bar. Correct if necessary. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. 2 Boiler removed from wall Drain down the heating circuit of the boiler only as described in 'To replace pump'. Note: It is not necessary to drain entire heating system to carry out this work. Ensure that gas and electrical supplies to boiler are turned off. Disconnect flue from either rear or top of boiler as applicable. Disconnect external controls connections, if applicable. Unscrew and disconnect five connections between fixing jig and boiler. Disengage pipe connections. Lift boiler off hanging bracket and place on a convenient working surface. Remove expansion vessel from boiler as described in previous section. Fit replacement vessel in reverse order to removal and check charge pressure. Replace boiler on wall, tighten all connections, gas connection first, ensuring that all sealing washers, filters and the cold water flow regulator are fitted before tightening. Reconnect flue system. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. Reconnect external controls connections, if applicable. Reconnect gas and electrical supplies to boiler. Check for gas soundness. To replace boiler thermistor Locate boiler thermistor on heating flow pipe on left hand side of boiler, see diagram 37.

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 ?