Heating and hot water for the professionals

ISOFAST

IN WARRANTY TECHNICAL HELPLINE
THIS IS A CAT I2E+ APPLIANCE

01773 828400

01773 828100
INSTALLATION AND OPERATING INSTRUCTIONS
ISOFAST F 28 E - ISOFAST F 35 E
Note! The boiler serial number is marked on the label attached to the inside of the drop down door. Refer to the 'Introduction' section page 3 for a description of the basic functions of the boiler. The 'Users' section describes how to safely operate the boiler.

USERS SECTION

Introduction.. Page 3 Commissioning... 3 Controls & lighting.. 4 Clock-Instructions for use.. 5 Draining... 5 Servicing/maintenance.. 5

INSTALLATION SECTION

Introduction.. Page 3 Technical data.. 6 Dimensions... 7 Heating system design... 7 Domestic hot water system design. 8 Boiler schematic.. 8 Fixing jig... 9 Piping system installation.. 9 Boiler location.. 10 Boiler installation.. 11 Flue installation.. 11 - 12 Electrical installation.. 13 Commissioning... 14 - 17 Safety devices... 17 - 18 Settings... 19

SERVICING SECTION

Routine cleaning and inspection.. Page 20 - 21 Replacement of parts.. 21 - 25 Boiler schematic... 26 Technical data... 27 Schematic wiring diagram... 28 Fault finding... 29 - 31 Spare parts... 31
Mandatory warning 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 your assistance.

INTRODUCTION

The ISOFAST F boiler is a wall mounted modulating combination boiler with electronic ignition providing central heating and instantaneous hot water. The boiler is equipped with a 4 litre domestic hot water storage vessel that ensures maximum hot water temperature stability during domestic demand. The boiler is of the I2E+ category for use with Natural Gas (G20) as distributed in the United Kingdom, or Butane (G30), Propane (G31) or Towns Gas (G130) with the appropriate conversion kit. The boiler has a fan assisted balanced flue which both discharges the products of combustion to and draws the combustion air from the outside of the room. The boiler is suitable for top outlet flue connection only but, can be fitted with horizontal flue, vertical flue or twin-pipe flue. Refer to flue catalogue for further details. 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 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. These instructions should be carefully followed for the safe and economical use of your boiler. Ancillary equipment A range of flue accessories are available including vertical flues, twin-pipe flues, bends etc. For further information contact your supplier. Substances Hazardous to Health The adhesives and sealants used in this appliance are cured and give no known hazard in this state. INSULATION PADS/CERAMIC FIBRE, GLASSYARN, MINERAL WOOL These can cause irritation to skin, eyes and the respiratory tract. If you have a history skin complaint you may be susceptible to irritation. High dust levels are usual only if the material is broken. Normal handing should not cause discomfort, but follow normal good hygiene and wash your hands before eating, drinking or going to the toilet. If you do suffer irritation to the eyes or severe irritation to the skin, seek medical attention.

COMMISSIONING

Gas safety (Installation and use) Regulations In your interests and that of gas safety, it is the law that ALL gas appliances are installed and serviced by a competent person in accordance with the above regulations. Gas leak or fault If a gas leak or fault exists or is suspected, turn the boiler off and consult the local gas supply company or your installation/service company. Air in the heating system Persistent air in the heating system may indicate leaks in the system or corrosion taking place. Call your Installation/Servicing company. Overheating safety In the event of a problem, the overheating safety devices cause safety shutdown of the boiler. If this happens, call your Installation/Servicing company. Boiler controls The control panel, located at the lower front of the boiler casing, see diagram 1, allows the boiler to be started, shut down, controlled and monitored during use. Flue Do not obstruct the outside terminal of the boiler.

On/Off button Summer/Winter mode selector Hot water temperature adjuster Hot water set point display Graphic display Heating temperature adjuster Heating set point display Display backlight

1.5 bar

Diagram 1

Hab 263

CONTROLS AND LIGHTING

Lighting the boiler :

Make sure that: q The boiler is connected to the electrical supply. q The gas service cock is open. Then follow the instructions below :
Press the On/Off button (1)
The pressure must be between 1 and 2 bar. If not, the system must be filled by a competent person.
To stop the boiler : Press button (1) Setting to the SUMMER position (Hot water only)
Appuyer mode button slectionner la position t Press the sur mode pourto select the summer symbol
Setting to the WINTER position (Heating + hot water)
Press the mode button slectionner la position hiver Appuyer sur mode pourto select the winter symbol
The actual temperature Temprature actuelle of thele circuit chauffage dans heating system
The flamelorsque leappears Apparat symbol brleur when the boiler is running est en fonctionnement
Illuminates when Apparat lorsque le the boiler lights brleur fonctionne
Adjusting the hot water temperature
Press + or - to ou - pour maximum temperature Appuyer sur + adjust theajuster la temprature of the hot water (38C to 60C) maximale de l'eau chaude sanitaire (38C 60C) Visual indication temprature demande Visualisation de laof set temperature
Adjusting the heating temperature
Press + or - to ou - pour maximum temperature Appuyer sur + adjust the ajuster la temprature of the heating (38C to 87C) maximale souhaite du circuit chauffage Visual indication temprature demande Visualisation de laof set temperature
To obtain domestic hot water, open a hot water tap. Hot water always has priority over central heating.

Hab 261

Hab 264
CLOCK - INSTRUCTIONS FOR USE
The boiler must be conected to the electrical supply and switched on. Setting the time Rotate the clock actuater mechanism clockwise, by hand, until the current time is indicated by the arrow, see diagram 2. Note: The time is set in 24 hour format, for example, 1300 for 1pm. Setting the programme "On" and "Off" times q Select the "On" times by pushing the white tappets to the outside, see diagram 2. q Select the 'Off' times by pushing the white tappets to the inside, see diagram 2. The clock shown in diagram 2 is set as follows: ON 07.00am to 09.00am (7-9) OFF 09.00am to 4.00pm (9-16) ON 4.00pm to 10.00pm (16-22) OFF 10.00pm to 07.00am (22-7)

To override or advance the clock The clock has a manual On/ Off switch, see diagram 3, which operates as follows : Upper position Heating On/Off as set by the tappets. Middle position Heating Off continuously

Reg 049 Reg 050

Lower position Heating On continuously

Diagram 2

Diagram 3

DRAINING

Protection against freezing If the boiler is to be out of use for any long periods during severe weather conditions, it is recommended that the whole system, including the boiler, be drained to avoid the risk of freezing. If in doubt, consult your servicing company. The ISOFAST 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. 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 will protect the complete heating system. Draining and filling Caution: The boiler is installed as part of a sealed system which must only be drained and filled by a competent person. Heating safety valve CAUTION: A heating safety valve with a discharge pipe is fitted to this boiler. The valve MUST NOT BE TOUCHED except by a competent person. If the valve discharges at any time, switch the boiler off and isolate it from the electrical supply. Contact your installation/service company. Pressure relief valve CAUTION: A domestic hot water pressure relief valve, with a discharge pipe is fitted to this boiler. The valve MUST NOT BE TOUCHED except by a competent person. If the valve discharges at any time, switch the boiler off and isolate it from the electrical supply. Contact your installation/service company.

SERVICING/MAINTENANCE

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 installation conditions and usage but, in general, once a year should be enough. Cleaning The boiler casing can be cleaned with a damp cloth followed by a dry cloth to polish. Do not use abrasive or solvent cleaners. Boiler casing CAUTION. Do not remove or adjust the casing in any way, as incorrect fitting may result in faulty operation. If in doubt, consult your installation/service company.

q q 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 0,5 bar (corresponding to a static head of 5 m w.g.) and allows a maximum system volume of 160 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 8. q Provision shall be made for a drain valve at the lowest point of the system. q 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. q In the case of an existing installation, it is ESSENTIAL that the system is thoroughly flushed prior to installing the new boiler.
Filling the system The ISOFAST is supplied with a built-in filliing device, see diagram 7.
DOMESTIC HOT WATER SYSTEM DESIGN
q Copper tubing or plastic Hep 20 may be used for the domestic hot water system. Unnecessary pressure losses should be avoided. q A flow restrictor limiting the flow through the boiler to a maximum of 16 l/min is fitted to the boiler. q The boiler will operate with a minimum supply pressure of 0,7 bar, but under reduced flow rate. Best operating comfort will be obtained from a supply pressure of 1 bar.
'Hard Water Areas' In areas where the water is 'hard', more than 200mg/litre, it is recommended that a proprietary scale reducer is fitted in the cold water supply to the boiler.

BOILER SCHEMATIC

25 A B C D E
- Domestic thermistor - Three way valve - Gas valve - Gas valve ignition module - Heating element - Micro accumulation vessel - Burner - Ignition electrode - Combustion chamber - Micro accumulation vessel thermistor - Main heat exchanger - Air pressure switch - Heating safety valve (3 bar) - Electronic control (PCB) - Domestic water flow sensor - Bypass - Domestic heat exchanger - Pump - Expansion vessel - Heating thermistor - Overheat safety thermostat - Flame sense electrode - Fan - Domestic safety valve - Loss of water sensor - Heating return - Cold water inlet - Heating flow - Domestic hot water outlet - Gas

Shy 120

Diagram 6

FIXING JIG

The fixing jig is made up, from left to right, as follows: A - Heating return fitting with isolating valve(v) and drain knob (u). B - Cold water inlet fitting with isolating valve (m)and factory fitted flow regulator and filter (not shown). C - Heating flow fitting with isolating valve (q), drain knob (r) and safety valve (s1). D - Domestic hot water outlet fitting with safety valve (s2). F - Gas fitting. G - Filling device.

u B G C r D F

Diagram 7
PIPING SYSTEM INSTALLATION
Heating system connections - Pipe diam. 22mm Hot water system connections - Pipe diam. 15mm q Gas connection - Pipe diam. 22mm q Domestic safety valve connection - Pipe diam.15mm q Heating safety valve connection - Pipe diam. 15mm
Water connection Connect the copper connections supplied, to the fixing jig fittings, see diagram 7. Connect the system pipework to the boiler observing the correct flow and return format as shown in diagram 8. Safety valve discharge Tee the domestic safety valve outlet pipe to the heating safety valve outlet pipe and extend horizontally to the outside wall. WARNING. It must not discharge above an entrance or window or any type of public access area. Connect the safety valve discharge pipe to the outlets of both the heating safety valve and the hot water safety valve, the discharge must be extended using not less than 15 m o.d. pipe, to discharge in a visible position outside the building, facing downward preferably over a drain. The pipe must have a continuous fall and be routed to a position so that any discharge of water, possibly boiling or steam, cannot create any danger to persons, damage to property or external electrical components and wiring. Tighten all pipe connection joints.
Gas connection The supply from the governed gas meter must be of adequate size to provide a constant inlet working pressure of 20 mbar (8 in w.g.). To avoid low gas pressure problems, it is recommended that the gas supply is connected using 22 mm pipe. q On completion, the gas installation must be tested using the pressure drop method and purged in accordance with the current issue of BS6891.
Gas Safety (Installation and use) Regulations In your interests and that of gas safety, it is the law that ALL gas appliances are installed and serviced by a competent person in accordance with the above regulations.
Additional expansion vessel (if required)

Boiler

Domestic water

Return Heating circuit Flow control valve
Bypass valve Filling device

Diagram 8

Sch 173a

Drain point

Cold supply

Pla 213

BOILER LOCATION
Clearances The position of the boiler must be such that there is adequate space for servicing. The recommended clearances are: 20 mm either side of the boiler. 600 mm at the front of the boiler. 300 mm below the boiler.
q Place template on wall in required position, making allowances for the necessary clearances etc. Note: It is permissible to install the boiler with smaller clearances than those quoted above PROVIDING that adequate consideration is given for Servicing/ Repairs at a later date. If any doubt exists, contact the Saunier Duval Technical Helpline 01773 828400.
Mark the position of the holes for the hanging bracket. q Drill, plug and fix the hanging bracket to the wall using suitable screws. q Check that the hanging bracket is level. q For horizontal flue system, mark the position for the flue hole as follows:

Diagram 9

nal. There must NEVER be a downward incline towards the boiler. Terminal position The minimum acceptable spacings from the terminal to obstructions and ventilation openings are shown in diagram 10. The boiler must be installed so that the terminal is exposed to the external air. Should any doubt exist as to the permissible position of the terminal, contact the Saunier Duval Technical Helpline 01773 828400. Terminal guard If a terminal guard is required, a suitable guard can be obtained from your supplier, Saunier Duval part number 85373. Cupboard or compartment ventilation The boiler can be fitted in a cupboard or compartment without the need for permanent ventilation.
Flue to rear of boiler q Mark correct position of hole from template. Flue to side of boiler q Mark the horizontal centre line for the hole on the rear wall. Extend the horizontal centre line to the side wall and mark the vertical centre line of flue hole as shown in diagram 9. 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 mm diameter core drill. For installations with internal access only use a 125 mm diameter core drill.
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 towards the termi-

Minimum dimensions (in mm) for the positioning of flue terminals

A B C D E F G H I L M N

Under a window.. 300 Under an air vent.. 300 Under a gutter.. 75 Under a balcony... 300 From an adjacent window.. 300 From an adjacent air vent.. 300 From vertical or horizontal air pipes.. 300 From an external corner of the building. 300 From an internal corner of the building. 300 From the ground or from another floor. 300 Between two terminals vertically.. 1500 Between two terminals horizontally.. 600

G C E F M

A B D I H L

Diagram 10

Ven 060b

Ins 050b

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 using a propriety cleanser such as Sentinel X300 to eliminate any foreign matter and contamination e.g. metal filings, solder particles, oil, grease etc. Note. Solvent products could cause damage to the system. Engage boiler upper part onto the hanging bracket. q Fit the washers between the boiler pipes and the inlet and outlet fittings on the fixing jig and connect the various couplings between the boiler and jig.

FLUE INSTALLATION

Top outlet flue - kit 85090 The boiler is only suitable for top outlet flue connection. Calculation of flue cutting lengths q Measure wall thickness e (mm), see diagram 11. q For side flues, measure distance from inside face of side wall to centre line of boiler and subtract 235 to get dimension a (mm). q Refer to table 2 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 12. When the dimension X measured on site is greater than that given in table 2, a flue extension kit will be required, refer to table 3 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 q Using the correct number of extension kits as table 3, measure dimensions a and e, see diagram 12. Cut both the inner and outer pipes to the dimensions given in table 4 Important: All cutting lengths should be measured from the push fit joint end of the extension pipe. Do not leave any burrs or sharp edges on the cut ends of the pipes.

Table 2 Flue cutting lengths
Cutting length (mm) Flue option outer pipe e + 160 inner pipe e + 244 Comments maximum wall thickness 'e' without extension 756 mm maximum distance 'x' without extension 990 mm

Hab 210/30a

Diagram 11 Diagram 12

Outer pipe

Cutting length

Inner pipe

Ven 089
Table 3 Number of extension kits required
Flue option Side flue (left or right) Dimension 'X' 991 to 1991 mm 1991 to 2991 mm No. of extension kits 1 2

Rear flue

side flue (left or right)

e + a + 145

e + a + 229
Note: Maximum flue length for 35kW model is 2 metres
Table 4 Flue extension cutting lengths
The standard flue kit 85090, see diag. 13, comprises : - External rubber sealing collar. A - Outer pipe... B - Plastic flange... C - Inner pipe... D - 2 O rings... E - Elbow.. F - Clamp and seal.. G - Gasket... H - Four screws... I
Flue option Side flue (left or right) outer pipe e + a -755 inner pipe e + a - 755 Comments maximum dimension 'X' without extension 990 mm
Installation of flue assembly q Fit rubber sealing collar (A), see diagram 13, into groove at the outer end of pipe (B). q Fit outer pipe (B) into wall with groove to the outside. q Pull pipe inwards to bring rubber sealing collar hard up against external wall, see diagram 14. q Fit internal plastic flange (C) onto outer pipe. Push along the pipe until engaged against internal wall. q From inside, insert inner pipe (D) into outer pipe. q Fit both O rings (E) into the flue elbow (F), 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. q Slacken the two screws and fit the clamp and seal (G) onto the elbow. q Take hold of the inner flue and push gently onto the elbow outlet taking care not to tear the O ring. Important: If the flue has been cut, ensure that there are no burrs that could damage the O ring. q Push the elbow clamp and seal over the outer flue. q For flue systems less than 1,5 m long, leave the restrictor (a) fitted in the fan outlet, see diagram 15.

Diagram 13

Diagram 14
q Remove the backing from the self adhesive gasket (H) and carefully fit gasket to base of flue elbow. q Fit elbow onto boiler and secure with the four screws (I).
Concentric flue system The maximum permissible length (L) for the concentric flue system is 3,5 m (F 28 E) or 2 m (F 35 E). For flue systems up to 1,5 m length, the restrictor (a) supplied fitted to the boiler, inside the fan outlet, must be left in place. For longer flue systems, the restrictor must be removed. For each 90 flue elbow used, (or two 45 elbows) the maximum permissible length (L) must be reduced by 1 metre.

Gasket

Diagram 15

Hab 249a

Pho 087

Pho 088

ELECTRICAL CONNECTION
Warning. This boiler must be earthed All system components must be of an approved type. Connection of the whole electrical system and any heating system controls to the electrical supply must be through a common isolator. Isolation should preferably be by a double pole switched fused spur box having a minimum contact separation of 3 mm on each pole. The fused spur box should be readily accessible and preferably adjacent to the boiler. It should be identified as to its use. A fused three pin plug and shuttered socket outlet may be used instead of a fused spur box provided that: a) They are not used in a room containing a fixed bath or shower. b) Both the plug and socket comply with the current issue of BS1363. The mains electrical supply must be maintained at all times in order to provide domestic hot water. Do not interrupt the mains supply with a time switch or programmer. WARNING: ON NO ACCOUNT MUST ANY EXTERNAL VOLTAGE BE APPLIED TO ANY OF THE TERMINALS ON THE HEATING CONTROLS CONNECTION PLUG. Warning: This appliance must be wired in accordance with these instructions. Any fault arising from incorrect wiring cannot be put right under the terms of the Saunier Duval guarantee. External controls The ISOFAST boiler is designed to operate at maximum efficiency at all times, but will be most efficient and economical when connected to a room thermostat. A suitable room thermostat is available as an acIns 060
cessory, Saunier Duval part number 40011. Please contact your supplier. The boiler will work for heating without a room thermostat being connected provided that the wire link fitted between the two terminals of the connector (E) is left in place, see diagram 17. Alternatively, a 230V room thermostat can be used but do not make any connection to the compensating resistor, see diagram 17. ON NO ACCOUNT must any electrical voltage be applied to any of the terminals of the external controls plug. Note: For further information, see the building regulations 1991 - Conservation of Fuel and Power - 1995 edition - appendix G, Table 4b.
The boiler is supplied with a mains lead attached. Connect this to the electrical supply.

Diagram 16

Leave link in place for no external controls.

Diagram 17

With voltage free room thermostat

Do not use

Without room thermostat

Sch 172

Sch 171
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 gas valve, see diagram 18.

Reg 018

Diagram 18

Filling the system

Press the mains 'On/Off' button
The display will indicate 0 bar pressure in the system
The warning light will illuminate

0.0 bar

Undo cap on automatic air vent on top of pump and leave undone.
Open the boiler isolating valves (v and q), the slot of the screw corresponds to flow direction. Fully open valve m by unscrewing anti-clockwise.

Reg 008

Open the tap (t) on the filling device and fill the system until the pressure indicated on the display is between 1 and 2 bar. The pressure must be between 1 and 2 bar

Hab 265

Bleed each radiator to remove the air, re-tighten bleed screws.
Leave the cap on the pump auto air vent open.
Open various hot water taps to bleed system.

Ins 061

Make sure the display indicates a system pressure of between 1 and 2 bar. Re-fill system as necessary.
The pressure must be between 1 and 2 bar

Ins 062

To stop the boiler : Press button (1) Setting to the WINTER position (Heating + hot water)
Press the mode pour slectionner la winter symbol Appuyer sur mode button to select the position hiver
The actual temperature Temprature actuelle of the le circuit system dans heating chauffage
Press + or - to ou - pour maximum temperature Appuyer sur + adjust the ajuster la temprature of the heating (38C to circuit maximale souhaite du 87C) chauffage Visual indication temprature demande Visualisation de laof set temperature
Adjust heating temperature to maximum. Check that any external controls, if fitted, are calling for heat (set room thermostat to maximum). q 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 the central heating system. q Gases driven towards the boiler will be automatically released through the automatic air vent. q The gases trapped at the highest point of the system must be released by bleeding the radiators. On reaching maximum temperature, the boiler should be turned off and the system drained as rapidly as possible whilst still hot. q Refill system to a pressure of between 1 and 2 bar and vent as before. q 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 when system is COLD.
Setting the heating output The heating output can be set without the use of a pressure gauge; proceed as follows: q Press the display light button and keep pressed for 5 seconds, see diagram 20. Note:The boiler has now been put into 'Service Mode', allowing certain adjustments to be made and diagnostic fault codes to be displayed. Refer to the 'Servicing Instructions' for further details. The heating output, in kW, is shown on the left hand side of the display, see diagram 21. q Remove the blanking plug from the front of the control panel to gain access to the heating adjusting screw. q Adjust the heating output by turning the screw clockwise to increase, anti-clockwise to decrease. q Refit blanking plug. Note: Adjustment of the heating output does not affect the domestic hot water output. For kW to Btu/hr conversion refer to table 5.

Table 5 kW to Btu/hr conversion
Setting the heating output

Diagram 20

Adjustment screw

kW 18 kW 34 35

Btu/hr 34,120 40,940 47,770 54,590 61,420 Btu/hr 102,360 109,180 116,000 119,420
Btu/hr 68,240 75,060 81,890 88,710 95,540
The heating output, in kW, is shown on the display.

Diagram 21

Setting the maximum heating temperature The maximum heating temperature can be preset at commissioning stage to suit the type of heating system. For example, for use with underfloor heating, the maximum heating temperature can be set to 53C. To adjust the maximum temperature, proceed as follows: q Remove the blanking plug (b) from the rear of the control panel to gain acess to selector switch SW1 (see diagram 22). Adjust toggles 1 and 2 to give the desired maximum heating temperature, see diagram Note: To adjust the maximum heating temperature it is only necessary to change toggles 1 and 2. Do NOT touch any other toggles. q Refit blanking plug.

Reg 053

Diagram 22
1=ON, 2=ON 53C. Maximum. 1=OFF, 2=OFF 73C. Maximum. 1=OFF, 2=ON 87C. Maximum. Factory setting 73C.

SAFETY DEVICES

The ISOFAST incorporates a visual display that indicates fault conditions, should they occur. In the event of a fault, the diplay will indicate, by means of pictograms and/or letters and numbers, exactly in which area the fault lies. Should the boiler fail to operate during Commissioning, the most likely fault is that the gas supply to the boiler has not been turned on or purged sufficiently or that there is no pressure in the heating system. These are indicated as follows :

Reg 052

Reg 051/UK
No gas supply This will be indicated on the display as a pictogram of a spark. To rectify this, proceed as follows: Switch off the boiler at the On/ Off push button. q Rectify the gas supply problem. q Restart the boiler by pressing the On/Off button.
General 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. Overheat safety In case of boiler overheating, the overheat thermostat will turn the boiler off. The thermostat, located on the heat exchanger flow pipe, will need to be manually reset. In case of power supply failure The boiler no longer operates. As soon as power supply is restored, the boiler will be automatically restarted. Frost protection The ISOFAST 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. 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 will protect the complete heating system.

-------------------------Insufficient system pressure This will be indicated on the display as a flashing warning indicating the system bar pressure is low. To rectify this the system must be re-filled, refer to 'Commissioning'.
-------------------------Other faults These are indicated on the display by a fault code and a telephone symbol. Further information on the fault codes can be found in the 'Servicing Instructions'.

SETTINGS

Gas valve setting All boilers are tested and factory set during manufacture. Should it be necessary to reset a gas valve, for example, after replacement, proceed as follows: q Shut down boiler. Minimum setting q Remove one electrical connector from the modulating gas valve coil, see diagram 23. q Connect a suitable pressure gauge. q Turn the OFF/Summer/Winter switch to the Summer position. q Turn the domestic hot water temperature adjuster to maximum setting. q Remove the protective cover from the gas valve adjuster. q Turn nut A, see diagram 23: CLOCKWISE: To increase the pressure. ANTICLOCKWISE: To decrease the pressure. Maximum setting q Reconnect the electrical connector removed from the modulating gas valve coil. q Remove the protective cover from the gas valve adjuster. q Turn nut B, see diagram 23: CLOCKWISE: To increase the pressure. ANTICLOCKWISE: To decrease the pressure. After adjustment, refit the cover to the gas valve adjuster. Bypass The ISOFAST has a built-in bypass. This must be adjusted according to the requirements of the system, refer to the flow rate pressure curve (diagram 4). The boiler is supplied with the built-in bypass open a half a turn. It is adjusted by turning the bypass screw (a), see diagram 24. Turn the screw clockwise to close the bypass.When using thermostatic radiator valves (TRVs) on all of the radiators, it is essential that a separate, adjustable bypass of 15 mm minimum diameter is fitted between the flow and return of the heating circuit, see diagram 8. Any bypass must be fitted before system controls.

Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. Reconnect all electrical connections and restore electrical supply. Open gas cock, operate boiler and re-check all joints for soundness. To replace fan Remove fan as described in Routine Cleaning and Inspection. Fit replacement fan in reverse order to removal. Reconnect electrical leads. To replace air pressure switch Locate air pressure switch situated inside sealed chamber on top right hand side. Remove air pressure switch tube from sensing probe on flue hood. Disconnect air pressure switch electrical connections. Undo screws on top of boiler securing air pressure switch to boiler and remove switch. Pull sensing tube off switch. Fit replacement switch to boiler in reverse order to removal, noting that pressure sensing tube fits to left hand connection on switch. To replace domestic water flow sensor Drain down hot water circuit of boiler only as described previously. Undo connecting nut from cold water inlet connection. Locate flow sensor on cold water inlet pipe to boiler inside controls area, see diagram 4. Carefuly pull off electrical connector from flow sensor. Pull out slotted metal clip securing cold water inlet pipe to flow sensor and carefully remove from sensor. Pull out slotted metal clip securing flow sensor to pump mounting and carefully remove sensor from boiler. Fit replacement sensor to boiler in reverse order to removal. To replace printed circuit board (PCB) Gain access to rear of control panel. Unclip and remove external controls/mains connection access cover. Unclip side clips and hinge up control panel cover to gain access to PCB, see diagram 5. Carefully pull off electrical connections to PCB. Unclip and lift out PCB. Fit replacement PCB in reverse order to removal. Note: 1) Make sure that PCB connections are fully pushed onto replacement PCB. 2) Set the heating temperature option to the same value as the old PCB, refer to 'Installation and User' instructions.

Diagram 4

Acc 010/Acc011

Ins 064

To replace pump Drain down heating circuit of the boiler only, as described previously. Note: It is not necessary to drain down entire heating system to carry out this work. Undo two fixing screws and remove pump retaining bracket from front of pump. Undo clips securing pump outlet hose connection to pump. Slide hose along pipe to clear pump outlet. Disconnect pump electrical connection from PCB. Transfer automatic air vent to replacement pump using new washers supplied. Re-connect electrical connection to PCB. Fit replacement pump in reverse order to removal. Open isolating valves on flow and return connections, refill, vent and pressurise boiler. Check for leaks. To replace domestic hot water heat exchanger Drain down heating and hot water circuits of boiler only as described previously. Note: It is not necessary to drain down entire heating system to carry out this work. Unscrew and remove cold water inlet pipe from fixing jig to water flow sensor. Supporting domestic heat exchanger, unscrew and remove two screws securing it onto pump mounting and 3-way valve/bypass housing. Remove heat exchanger from boiler. Fit replacement heat exchanger in reverse order to removal using new seals, supplied. Note: Heat exchanger mounting screws are offset to ensure correct fitting of replacement. To replace 3-way valve head Locate 3- way valve in centre of lower controls area. Remove electrical plug from valve head. Pull out slotted metal clip from valve body and remove valve head from body. Fit replacement valve head in reverse order to removal. Note : 1) When refiting clip, ensure that letters OK are as shown in diagram 6. 2)It is not necessary to drain boiler to carry out this work.