Brivis Service Manual BX3 Buffalo Gas Ducted Heater

Brivis Service Manual BX3 Buffalo Gas Ducted Heater Service shall be carried out only by Authorised Personnel. This Service Manual must NOT be left with the Owner, or distributed to other persons not permitted to obtain this information by Brivis Climate Systems. 281 Issue 1 - Service Manual - BX3

Issue Date Description 1 March 2015 Release of the BX3 model SCOPE This Service Manual contains information relevant to servicing a Brivis CC3 Gas Ducted heaters. It is intended for Service personnel who have received adequate training on Brivis Gas Fired Ducted Central Heaters, in particular Brivis series heaters. Brivis Classic BX3 Buffalo Model Gas Ducted Heater The New Brivis Buffalo BX3 series ducted central heater is an updated Model to the Classic Buffalo range heater. The Brivis BX3 Ducted central heater has a new electronic control system and combustion now fan forced. The model range as follows: Model KiloWatt Star Rating BX315 15 3.9 BX320 20 3.8 BX326 26 3.5 The New Brivis Buffalo BX3 Gas ducted heater consists of the following features: The Tytronics HCDSI24-1DT Gas Fired ducted Heater control board with LED diagnostic display. A direct main burner ignition system. Single speed fan forced combustion process. Supply air and flame roll out over temperature safety shutdown switches. An external pressure switch so once the combustion fan pressure is sufficient it ensures the correct burner operation. Fixed Speed main circulating fan, with three speed options. All model heaters operate on a conventional 24Volt manual or programmable thermostat. 281 Issue 1 - Service Manual - BX3 ii

The main sections covered include: Heater operation Technical Specifications Thermostat Installation Component Operation Installation and Commissioning Troubleshooting Main Components Servicing Dismantling Procedures Further information on installation and operation of Brivis Buffalo BX3 heaters can be obtained from the Heating Installer s Manual and Heating Owner s manual Note: Safety Warning DO NOT PLACE ARTICLES ON OR AGAINST THIS APPLIANCE. DO NOT USE OR STORE FLAMMABLE MATERIALS NEAR THIS APPLIANCE. DO NOT SPRAY AEROSOLS IN THE VICINITY OF THIS APPLIANCE WHILE IT IS IN OPERATION. DO NOT MODIFY THIS APPLIANCE. 281 Issue 1 - Service Manual - BX3 iii

Table of Contents 1.0 HEATER OPERATION... 1 1.1 Operation Overview... 1 1.2 Circuit Diagram... 2 1.3 Wiring Colour Code... 3 1.4 BX315 Technical Information... 4 1.5 BX320 Technical Information... 5 1.6 BX326 Technical Information... 6 1.7 Motor Wiring Diagrams... 7 2.0 Thermostat Installation and Wiring... 8 3.0 COMPONENT OPERATION... 10 3.1 BX3 Gas Ducted Unit Components... 10 3.2 Gas Valve Operation... 10 3.3 Spark Igniter... 11 3.4 Flame Sensor... 11 3.5 Combustion Fan Operation... 11 3.6 Burner... 12 3.7 HCDSI24-1 Control Board... 12 3.8 Pressure Switch... 13 3.9 Main Fan Assembly Operation... 13 3.10 Operation Flow Charts... 14 3.11 Heater Shut down Flow Chart... 15 4.0 INSTALLATION & COMMISSIONING... 16 5.0 TROUBLESHOOTING... 16 5.1 LED Flash Codes... 16 5.2 One Flash - Over Heat Condition... 18 5.3 Two Flashes - Pressure Switch Inactive... 19 5.4 Three Flashes Purge / Interwait... 20 5.5 Four Flashes - Pressure Switch Lockout... 20 5.6 Five Flashes Ignition Lockout... 20 5.7 Six Flashes Valve Fault Lockout... 20 5.8 Seven Flashes Over Temp Lockout... 21 281 Issue 1 - Service Manual - BX3 iv

5.9 Eight Flashes Frequency Lockout... 21 5.10 Nine Flashes - Flame Lockout Invalid Flame... 22 5.11 Ten Flashes False Flame... 22 5.12 Eleven Flashes - SafeStart Lockout... 22 5.13 Twelve Flashes Secondary Fafeguard Timing Fault... 22 5.14 Three Slow Flashes Ground Fault Lockout... 23 5.15 Three Slow Flashes - Ground Fault Lockout... 23 5.16 Three Slow Flashes - Ground Fault Lockout... 24 6.0 MAIN COMPONENTS SERVICING... 25 6.1 Gas Valve Servicing... 25 6.2 Combustion Fan Servicing... 27 6.3 Spark Igniter Servicing... 28 6.4 Flame Sensor Servicing... 28 6.5 Pressure Switch Servicing... 29 6.6 Main Fan Assembly Servicing... 29 6.7 Unit Operation... 30 7.0 DISMANTLING PROCEDURES... 31 7.1 Burner Assembly Removal... 31 7.2 Gas Manifold Assembly Removal... 31 7.3 Gas Valve Removal... 32 7.4 Pressure Switch Assembly Removal... 32 7.5 Combustion Fan Removal... 32 7.6 Main Fan Assembly Removal... 34 7.7 HCDSI24-1 Electronic Control Board Removal... 35 7.8 240 to 24 Volt Transformer Removal... 35 7.9 Heat Exchanger Removal... 36 8.0 Flue Instructions... 38 281 Issue 1 - Service Manual - BX3 v

1.0 HEATER OPERATION This section provides an overview of the operation of the BX3 series heaters. It is vital that an understanding of how BX3 series heaters, and their components, operate in order to service the BX3 Series heater effectively and efficiently. 1.1 Operation Overview The Brivis BX3 series is a 3 Star range suited for internal installations on Natural Gas only. The BX3 series heater has a combustion system consisting of a fixed speed combustion fan and direct spark ignition module. The gas valve is on/off only i.e. not modulating and the rate is set for each model. Once the combustion fan pressure switch validates the system pressure is correct the normal start up sequence will begin, refer below. Upon power up the HCDSI24-1 control board shall perform a system check and allow all of its inputs and outputs to settle. The HCDSI24-1 initiates an ignition cycle upon receiving a call for heat from an external thermostat. The following will occur: The micro-controller shall check that the external flame safety guard is operational. As the flame circuit is earth referenced, additional checks are made to detect an earth disconnect. The control board will do a safety check and make sure the pressure switch circuit is open. The unit then energises the combustion fan motor, and verifies that the pressure switch closes. The unit will operate for the pre-purge time before continuing to the safety time. The unit shall simultaneously energise the spark igniter and gas valve with the intention to light the main gas burner. The igniter shall be energised for at most the duration of the safety time or until a valid flame signal is detected which ever occurs first. Safety time shall cause the gas valve and combustion fan to remain energised for the duration of the call for heat. 20 seconds after the warm up period the control board will then power the main supply air fan to its set speed. 281 Issue 1 - Service Manual - BX3 1

1.2 Circuit Diagram Brivis Buffalo BX3 281 Issue 1 - Service Manual - BX3 2

1.3 Wiring Colour Code Low Voltage (From left to right refer to diagram in section 1.1) Pin Function Colour 1 Gas Valve Violet 2 Gas Valve Grey 3 Pressure Switch Yellow 4 W White 5 Hi-Limit Black 6 24Vac (Hi-Limit) Orange 7 24Vac Red 8 Ground Green High Voltage (From left to right refer to diagram in section 1.1) Pin Function Colour 1 Flame Sense White 2 Neutral Blue 3 Combustion Fan Brown 4 Circulation Fan Red 5 Active Brown Wiring Colour 281 Issue 1 - Service Manual - BX3 3

1.4 BX315 Technical Information AGA Approval No.: 8159 Energy Label Star Rating: 3.9 stars 152 MJ/m 3 /Year Dimensions Width Height Depth Weight Cabinet 420 850 775 57Kg Duct Connection 300mm Gas Type Natural Gas Input (max) Output (max) Burner Pressure (max) Gas Injector Orifice Main Burner Fan Motor Model Model No. Watts Amps Capacitor Fan Impellor Size 68MJ/h 15kW 0.85KPa 2.25mm Fasco 808555MVA-A22 250 Watts 1.80Amps 6uF 255mm x 180mm (9 X7 ) Combustion Fan: Model. Fime GRO4100 Model No. FL120042Y - 13 Watts. 60 Watts Amps 0.55 Amps Resistance 40.6 Ω Pressure switch 115pa Return Air Grille Size With Filter 0.35m 2 No Filter 0.24m 2 Airflow @ Total Static Pressure 50 Pa 75 Pa 100 Pa 125 Pa Standard 620l/s 590l/s 560l/s 530l/s Gas Valves: VR8215S,T Honeywell Main Burner:. In shot Burner Ignition System Tytronics HCDSI24-1DT control box Intermittent Sparking Pilot. Heat Exchanger: Aluminised Steel Tubes Control Fuse: 2 Amp type 3AG. Slow blow Transformer: Model B024702 240 24/12V, 50HZ, 1.75Amps. Over Temperature Switch: Supply Air Compartment: Texas Inst Klixon Oil 1747 L110 (opens at 110 o C). Flame Roll-Out Sensor (AFRO): Texas Inst Klixon Oil 1747 L90 (opens at 90 o C).. Electronic Heater Controller: Tytronics HCDSI24-1DT FEATURES: Tytronics HCDSI24-1DT control box with LED diagnostic display, flame roll-out Klixon, direct main in-shot burners, induced combustion airflow, circulation air fan has an optional 3 speeds for heating. Wiring terminal connection for thermostat / system with heat. 281 Issue 1 - Service Manual - BX3 4

1.5 BX320 Technical Information AGA Approval No.: 8159 Energy Label Star Rating: 3.8 stars 154 MJ/m 3 /Year Dimensions Width Height Depth Weight Cabinet 420 850 775 57KG Duct Connection Gas Type: Input (max) Output (max) Burner Pressure (max) Gas Injector Orifice Main Burner Fan Motor Model Model No. Watts Amps Capacitor Fan Impellor Size Standard 300mm or 350mm Natural Gas 92MJ/h 20kW 0.82KPa 2.25mm Fasco 808555NVA-A13 315 Watts 2.5 Amps 10 uf 255mm x 180mm (9 X7 ) Combustion Fan: Model. Fime GRO4100 Model No. FL120042Y - 13 Watts. 60 Watts Amps 0.55 Amps Resistance 40.6 Ω Pressure switch 115pa Return Air Grille Size Standard XA With Filter 0.36 m 2 0.38 No Filter 0.25 m2 0.26 Airflow @ Total Static Pressure 50 Pa 75 Pa 100 Pa 125 Pa Standard 640l/s 615l/s 585l/s 560l/s XAir 685 655 630 600 Gas Valves: VR8215S,T Honeywell Main Burner:. In shot Burner Ignition System Tytronics HCDSI24-1DT control box Intermittent Sparking Pilot. Heat Exchanger: Aluminised Steel Tubes Control Fuse: 2 Amp type 3AG. Slow Blow Transformer: Model T- B024702 240 24/12V, 50HZ, 1.75Amps. Over Temperature Switch: Supply Air Compartment: Texas Inst Klixon Oil 1747 L110 (opens at 110oC). Flame Roll-Out Sensor (AFRO): Supply Air Compartment: Texas Inst Klixon Oil 1747 L90 (opens at 90oC). Electronic Heater Controller: Tytronics HCDSI24-1DT FEATURES: Tytronics HCDSI24-1DT control box with LED diagnostic display, flame roll-out Klixon, direct main in-shot burners, induced combustion airflow, circulation air fan has an optional 3 speeds for heating. Wiring terminal connection for thermostat / system with heat. 281 Issue 1 - Service Manual - BX3 5

1.6 BX326 Technical Information AGA Approval No.: 8159 Energy Label Star Rating: 3.5 stars 159 MJ/m 3 /Year Dimensions Width Height Depth Weight Cabinet 579 894 1030 67kg Duct Connection 350mm or 400mm Gas Type Input (max) Output (max) Burner Pressure (max) Gas Injector Orifice Main Burner Natural Gas 120MJ/h 26kW 0.75KPa 2.25mm Fan Motor Standard Model Fasco Model No. 806155082-17 Watts 600 Watt Amps 4.4 Amps Capacitor 25uF Fan Impellor Size 284mm x 265mm (10 X10 ) Combustion Fan: Model. Model No. Watts. Amps Resistance Pressure switch Fime GRO4100 60 Watts 0.55 Amps 24.3 Ω 50pa Return Air Grille Size Standard XA With Filter 0.41 m 2 0.42 No Filter 0.28 m 2 0.29 Airflow @ Total Static Pressure 50 Pa 75 Pa 100 Pa 125 Pa Standard 805l/s 780l/s 760l/s 740l/s XA 825 805 785 765 Gas Valves: VR8215S,T Honeywell Main Burner:. Inshot Burner Ignition System Tytronics HCDSI24-1DT control box Intermittent Sparking Pilot. Heat Exchanger: Aluminised Steel Tubes Control Fuse: 2 Amp type 3AG. Slow blow Transformer: Model T- B024702 240 24/12V, 50HZ, 1.75Amps. Over Temperature Switch: Supply Air Compartment: Texas Inst Klixon Oil 1747 L90 (opens at 90oC). Flame Roll-Out Sensor (AFRO): Texas Inst Klixon Oil 1747 L90 (opens at 90oC).. Electronic Heater Controller: Tytronics HCDSI24-1DT FEATURES: Tytronics HCDSI24-1DT control box with LED diagnostic display, flame roll-out Klixon, direct main in-shot burners, induced combustion airflow, circulation air fan has an optional 3 speeds for heating. Wiring terminal connection for thermostat / system with heat. 281 Issue 1 - Service Manual - BX3 6

1.7 Motor Wiring Diagrams Model Fasco 250W 808555MVA-A22 Fasco 315W 80855NVA-A13 Fasco 600W 806155082-17 Power 240Volts 240Volts 240Volts Maximum Current 1.8 Amp 2.5 Amp 4.4 Amp Main Fan Motor Capacitor 6 µf 10 µf 25 µf High Winding Resistance @ 20 C Medium Winding Resistance @ 20 C Low Winding Resistance @ 20 C 20.6 Ohms 11 Ohms 6.9 Ohms 26.1 Ohms 14.6 Ohms 8 Ohms 31.6 Ohms 18 Ohms 9.3 Ohms Impellor Size diam. x width 255mm x 180 mm 255mm x 180 mm 284mm x 265 mm 281 Issue 1 - Service Manual - BX3 7

2.0 Thermostat Installation and Wiring Wiring the Thermostat (Heating only) Brivis Manual and Brivis Programmable Thermostats can be wired directly to a Classic heater for heating only applications. Wiring the Manual and Programmable Thermostats. Run twin core cable no less than 0.75mm² in cross section from the heater Terminal Block to the thermostat location. Remove thermostat backing plate from the front cover and mount on the wall. Draw wires from the wall cavity, connect R & W terminals on the heater Terminal Block to the R & W terminals on the thermostat, refer Diagram 4. Insert batteries and mount thermostat front cover onto the backing plate. For more information refer to the Installation Guide and Operating Manual supplied with the Brivis Manual or Programmable Thermostats. Note: On the terminal block C, Y, G, TW1 & TW2 are not active. Diagram 4. BX3 Thermostat Connection Terminal block Field Supplied Twin-core, figure 8 0.75mm² cable W R T/STAT Grommet 281 Issue 1 - Service Manual - BX3 8

Wiring the Brivis Programmable Thermostat (Add-On & Fan Only) The BX3 does control board does not have provision for Add-On cooling. For Add-On cooling operation the unit can be configured. Refer to Diagram 5 for interconnection to the unit and wall control for Add-On cooling. For heating only systems Fan Only operation can be configured as shown in Diagram 5, the only connection not required is Y. Diagram 5. A N 1 2 5 3 4 3 Notes: 1. All electrical works to comply with relevant regulations. 2. Requires Brivis programmable Thermostat. 3. For field supplied parts refer to Table 2. 8 W R 6 Blue Gray Green White Red Orange Black 9 7 1 To Y terminal on wall control To Brivis Programmable Controller Only Note: On the heater terminal block C (Blue), Y (Gray), TW2 (Orange) & TW1 (Black) are all inactive for the above configuration. Table 2: Supplied & Field supplied components for Add-On connection Item Description Field Supplied No: Y/N 1 ¼ spade (female) + cover + sheathed conductor 0.75mm² (min) Y 2 Fan Motor N 3 Red conductor N 4 Relay NC - 24Vac coil switching 240Vac Y 5 Heater Control Board N 6 CDU Compressor Relay Y 7 Sheathed conductor wire, minimum 0.75mm² cross-sectional area Y 8 Sheathed conductor wire, minimum 0.75mm² cross-sectional area Y 9 Terminal block on Heater N 10 Brivis Programmable Controller Purchase from Brivis 281 Issue 1 - Service Manual - BX3 9

3.0 COMPONENT OPERATION 3.1 BX3 Gas Ducted Unit Components Main Circulation fan compartment Thermostat connection Transformer Pressure switch Control Board Combustion Fan Gas Valve Flame roll out plate Burner Assembly Flame roll out switch 3.2 Gas Valve Operation The gas valves function is to provide gas for combustion. The gas valve is a Honeywell VR8215S,T gas valve. For natural gas it has been optimised for direct ignition application and includes a on and off switch and a pressure regulator. The gas valve is controlled by the HCDSI 24-1 PCB control. Please see the technical data sheet for the optimum gas pressures. 281 Issue 1 - Service Manual - BX3 10

3.3 Spark Igniter The Spark Igniter consists of a spark probe and earth probe used to create a fixed spark gap. HCDSI 24-1 generates a spark from the sparker canister across the gap of the sparker probe. This spark gap is located beneath the burner port at one end of the burner rack. Once ignition has occurred and the flame is sensed, the spark igniter stops sparking. 3.4 Flame Sensor The Flame Sensor consists of a single metal probe and is located beneath the burner at the opposite end of the burner rack from the Spark Igniter. When flame is present at this burner, a small electric current passes from the flame sensor through the flame to the closest ground or earth point (either the Burner or Heat Exchanger). HCDSI 24-1 control monitors the Flame Sensor current level. If it is within an allowable range, the controls then allow for normal operation. 3.5 Combustion Fan Operation The combustion fans primary function is to draw air and flame through the heat exchanger. If this combustion airflow is reduced, the combustion quality will be reduced and sooting may occur. If the airflow is reduced considerably, the flames will not be drawn into the heat exchanger. (Fortunately, there are measuring devices to prevent these occurrences from causing an unsafe condition). The combustion fan operates at a fixed fan speed, and is switched on and off by the HCDSI 24-1 control. When the fan is in operation, the suction effect of the fan creates a (vacuum)+ inside the heat exchanger from the heat exchanger inlet ports all the way through to the combustion fan box on which the combustion fan is mounted. During start-up, the combustion fan performs a pre-purge for approximately 15 seconds. This ensures there is no un-burnt fuel in the heat exchanger. During this phase, the required quantity of air for adequate combustion is confirmed by a vacuum pressure switch. If the airflow is not sufficient, the vacuum pressure will be too low, and the pressure switch will not close circuit. A pressure switch error will be logged and no ignition will occur. During normal operation the vacuum pressure generated by the combustion fan is continually monitored by the pressure switch. If this vacuum pressure drops too low, the pressure switch will go open circuit, the burners will the shut down and an error will be logged. During a normal shut down sequence, the burners will shut down, and the combustion fan will switch off after 5 seconds. Combustion Fan Motor Fime Winding Resistance @20 o C Resistance Reading 24.3 Ohms 281 Issue 1 - Service Manual - BX3 11

3.6 Burner The burners are known as In-shot burners. They consist of a venturi, which helps to draw air into the top of the burner, near the injectors. This is known as primary air and is used for gas mixing before combustion occurs. Once the gas and primary air leave the burner port, at the exit of the burner, combustion begins, and secondary air is added to the flame from the suction force developed from the combustion fan. There is a cross lighting gallery near the burner exit, which allows for cross ignition between each adjacent burner. 3.7 HCDSI24-1 Control Board The HCDSI24-1 control is a single printed circuit board (PCB) assembly, mounted within a plastic enclosure. The controller provides status and diagnostic information directly through the use of a Green LED indicator. An additional Red LED provides direct indication of the pressure switch status. HCDSI 24-1 Control Board Ignition Plug LED s 240Vac connection. 24 Volt AC Connections Ignition coil 2 amp fuse 281 Issue 1 - Service Manual - BX3 12

3.8 Pressure Switch PRESSURE SWITCH: The pressure switch is a Cleveland NS2 series diaphragm pressure differential activated switch. The BX3 models have one pressure switch. Please refer to the technical data sheets for the operating range. The pressure switch for proving sufficient combustion airflow is located in the vicinity of the combustion fan and measures the vacuum pressure in the heat exchanger outlet box. If there is insufficient vacuum pressure to ensure safe and reliable ignition, or combustion quality, the switch will go open circuit and the 24 volt supply to the gas valve cut. 3.9 Main Fan Assembly Operation ROOM AIR FAN A centrifugal fan and Permanent Split Capacitor (PSC) motor, housed in a metal scroll are used for room air circulation, and this is contained within the fan cabinet. The room fan has 3 speed settings and can be adjusted to obtain the required air flow. The three settings are low, medium and high and can be changed by shifting the position of the fan spade terminal. Note: Refer to data sheets for fan and capacitor specifications. 281 Issue 1 - Service Manual - BX3 13

3.10 Operation Flow Charts Heater Start up Flow Chart Call from heat from the thermostat System checks: Flame sensors earth Pressure switch open Combustion fan hold off (2 sec) Pressure Switch Closes Combustion Fan Prepurge (20 sec) Ignition retry phase activated (5 Max number of Ignition attempts) Ignition Flame detect time Has flame been detected within 5 seconds? No Yes Flame validate time Has flame been present for 5.5 seconds? No Initiate main fan hold-off time of 20 seconds. Fan speed ramps up to required speed Normal operation continues Steady state operation 281 Issue 1 - Service Manual - BX3 14

3.11 Heater Shut down Flow Chart Heater thermostat switched off Gas valve closes Combustion fan post-purge (5 sec) Circulation Fan Off Delay 80 Seconds Main fan turns off 281 Issue 1 - Service Manual - BX3 15

4.0 INSTALLATION & COMMISSIONING REFER TO HEATING INSTALLER S MANUAL FOR INSTALLATION AND COMMISSIONING INSTRUCTIONS. 5.0 TROUBLESHOOTING Most failure modes will result in a fault being logged in the HCDSI 24-1 control board. These faults can be viewed at the control Board. A brief description of each fault code is shown below, followed by detailed troubleshooting for each fault code. 5.1 LED Flash Codes One green LED is used to display the status of the HCDSI24-1DT. The LED flashes up to 12 times on a 4.8-second repeat to indicate fault status. LED NORMAL OPERATION Slow single flash (200mS flashcode: 111111110000000000000000) Slow double flash CONDITION HCDS123 is functioning normally, and is in an idle state HCDS123 is functioning normally, with the thermostat closed (200mS flashcode: 111100001111000000000000) FAULT One flash repeated every 4.8 Overheat condition seconds (200mS flashcode: Overheat in progress 100000000000000000000000) Overheat switch is disconnected or O/C Pressure Switch inactive. Fan running but pressure Two flash (200mS flashcode: switch 101000000000000000000000) is still open. Fan stopped but pressure switch is still closed Three flash ( 200mS flashcode: Purge / Interwait 101010000000000000000000) Timer operating eg: Stat off during flame Establishment time Flame establishment time elapsed without flame Pressure Switch Lockout. Pressure Switch not Four flash (200mS flashcode: functional. 101010100000000000000000) Fail to close timeout / fail to open timeout Five flash (200mS flashcode: Ignition Lockout - failure to ignite flame. Max number of 101010101000000000000000) re-ignition / spark restoration attempts has been reached. Six flash (200mS flashcode Valve Fault Lockout - Valve Detection Failure. 101010101010000000000000) Valve is disconnected. Gas valve drive relay contacts fail to close. Gas valve drive Triac fault: Open or half-wave. Seven flash (200mS flashcode: Over-temp Lockout. Too many Hi-Limit activations in 101010101010100000000000) latest heat cycles. Hi-Limit activation continues longer than Hi-Limit fan + cool down times. Eight flash (200mS flashcode: Frequency Lockout - Timing fault. 101010101010101000000000) Supply frequency outside operating limits. Microprocessor clock outside operating limits. 281 Issue 1 - Service Manual - BX3 16

Nine flash (200mS flashcode: Flame Lockout - Invalid Flame A/D valve. 101010101010101010000000) Flame sense hardware fault. Ten flash (200mS flashcode: False Flame 101010101010101010100000) Invalid flame sensed during safe start check or IDLE - hardware fault. Eleven Flash SafeStart Lockout - Secondary safeguard timing fault. (200mS flashcode: Main valve safeguard too slow or failed to activate- 101010101010101010101000) hardware fault. Twelve flash SafeStart Lockout - Secondary safeguard timing fault. (200mS flashcode: Safestart checks did not complete in time, no hardware 101010101010101010101010) fault recorded. 3 Slow flashes Ground Fault Lockout - Flame sense fault. (200mS flashcode: Flame variation detected due to poor earth connection to 1111100111100111100000000) chassis ground. A lockout is a result of a detected fault condition, caused by an operational or a safeguard fault. In the case of a lockout, the unit shall both de-energise the triac drive and stop the control signal to the relay drive circuit. Consequently the gas valve is completely isolated and will close. The unit shall remain in lockout until manually reset. The lockout failure mode shall be distinguished by the status LED flash-code. Each individual flash shall have a 200milli-second sub-period. The sequence shall repeat with an approx five second period. Lockout shall be cleared by any of the following: Power isolation for more than 2 seconds Cycle of the Thermostat input 6 times within a 60 seconds, each cycle must be at least 2- seconds in duration. 281 Issue 1 - Service Manual - BX3 17

5.2 One Flash - Over Heat Condition Reason Overheat condition This errors will appear whilst an over temperature is current. The overheat switch or flame rollout circuit is open and measuring a temperature greater than the temperature of the switch (See chart below). The heater s fan will be forced to operate at its predetermined speed for a specific time period. Supply air over heat and Flame Roll - out All Brivis BX3 models have a supply air over heat switch located near the supply air discharge and is activated when the supply air reaches 90 C on the BX326 but on the BX315 and BX320 are activated at 110 C. Also if the flame roll out occurs the switch will interrupt the 24 Volt power to the gas valve if flame rollout and over heat occurs. The following will occur. The power supply to the gas valve will be terminated. The fan will operate immediately, if not already operating. Once the over temperature condition of the switches has cleared and the switch resets (i.e. switch closes within a specific time), a cool down period will operate for a duration of 120sec. Then the normal heating cycle can commence again, provided the wall control is still calling for heat. Service Check List: Check the temperature rise value of the supply air thermistor and nearest outlet temperature, over the room temperature (Return air intake temperature). A 47 0 C. Temperature rise will indicate a true overheat condition. Check there are sufficient outlets open on the duct system. Check the return air filter (if fitted) is sized correctly and is clean. Check that the fan speed is sufficient for the system so that overheating will not result. Check the fan motor is functioning correctly, and is not blocked or obstructed. Check the ducting has not been crushed, damaged or incorrectly sized. Check the return air intake is not subjected to a high temperature from an external source. Check the wire loom and plug connections to the switch are not open circuit, i.e. wire fallen off switch. Supply air and Flame roll our switch ratings Unit S/Air over heat switch Flame Roll out switch BX315 110 C 90 C BX320 110 C 90 C BX326 90 C 90 C 281 Issue 1 - Service Manual - BX3 18

5.3 Two Flashes - Pressure Switch Inactive Reason: Pressure switch inactive A pressure switch within the appliance provides proof of combustion airflow. During the ON phase of the heating cycle the pressure switch has opened, indicating a loss in vacuum pressure. The heating cycle will be forced to its OFF state and a restart initiated. If this occurs continuously the unit will lockout and manual reset will be required. During a heating cycle, the unit responds to the state of this switch in the following ways. Pressure switch fails to open. Once the unit is calling for heating the control board will first ensure the combustion air pressure switch is open (no air flowing) before energising the combustion fan. However If the pressure switch is closed then the unit shall wait for the switch to open for as long as the call for heat is present. If the pressure switch remains closed longer than 30 seconds the corresponding two flash warning flash code is displayed. If the pressure switch remains closed longer than 4 minutes, the unit shall lockout and the four flash fault code is flashed on the status LED. Once lockout occurs, the combustion fan turns off. Pressure switch fails to close. If the combustion fan pressure switch does not close shortly after the combustion fan has been energised the unit shall keep the combustion fan energised for 4 minutes, until either the pressure switch closes or the call for heat is removed. If the pressure switch remains open longer than 30 seconds, the 2 flash fault code is displayed. If the pressure switch remains open longer than 4 minutes, the unit shall lockout and the four flash fault code is flashed on the status LED, once lockout occurs the combustion fan turns off. Service Check List Vacuum Pressure Checking Procedure Measure vacuum pressure at the pressure switch during pre-purge (or force an overheat condition, by breaking the overheat switch circuit, to operate the combustion fan). Perform these pressure checks without the pressure switch connected to the pressure hose. If vacuum pressure is above specification If the flue has no blockage and you find the vacuum pressure is above the pressure switch s specified value and pressure switch error still occurs, then the pressure switch may be faulty and should be replaced. If vacuum pressure is below specification 1. Vacuum pressure hoses are not fitted correctly check hose connections 2. Vacuum pressure hoses have perished and cracked causing vacuum pressure loss check for deterioration. 3. Water trapped in the vacuum pressure hose check for water traps or presence of moisture in hoses. Make sure there is no water in the hose when servicing the system. 4. Excessive heat exchanger leakage resulting in vacuum pressure loss check heat exchanger for leakage. 5. Combustion fan may be faulty check according to procedure in section (Combustion Fan) 6. Flue piping is too restrictive check against allowable flue pipe configuration specification including the flue cowl. 7. Flue pipe has collected excessive condensate check for potential collection points (there must be a continual fall back to the heater 20mm rise per Metre). 8. Check pressure switch pressures on 2 flashes pressure switch lockout. 281 Issue 1 - Service Manual - BX3 19

5.4 Three Flashes Purge / Interwait Purge / Interwait Timer operating Eg: Stat off during flame establishment time Flame establishment time elapsed without flame This failure can be caused by the unit failing to ignite at the start of its on time cycle without a flame being detected. Service Check List: 1. Check gas pressure or supply pressure 2. Check ignitor is in its right position 3. Check ignitor lead 4. Check gas valve loom and connections 5. Check flame sensors 6. 5.5 Four Flashes - Pressure Switch Lockout Reason Pressure switch lockout If the combustion fan pressure switch does not close shortly after the combustion fan has been energised, the unit shall keep the combustion fan energised for 4 min, until either the pressure switch closes or the call for heat is removed. If the pressure switch remains open longer than 4 minutes, the unit shall lockout. Once lockout occurs, the combustion fan turns off. Service Check List: 1. Refer to Check List for 2 flash Pressure switch inactive 5.6 Five Flashes Ignition Lockout Reason: Ignition lockout failure to Ignite flame within the maximum allowable Ignition retry phase. There is a maximum of 5 re-ignition attempts before the control board will lockout. If a valid flame is undetected for the duration of the flame establishment or first safety time, the unit shall enter lockout and flash 5 time fault code on the status LED. The safety time represents the maximum time gas can flow without combustion occurring. Service Check List: 1. Check the igniter high tension lead and terminal connections. 2. Check the igniter rod is clean 3. Check the igniter ceramic insulation is not cracked or damaged. 4. Check igniter is in its right location 5. Check gas pressure or supply pressure 6. Check gas valve loom and connections 7. Check if the control board is sparking 5.7 Six Flashes Valve Fault Lockout Reason: 281 Issue 1 - Service Manual - BX3 20

The gas valve has failed to open and has Detected as failure Gas valve drive relay contacts fail to close Short open or half wave Gas valve drive triac fault Service Check List: 1. Check the gas valve wiring has not been disconnected. 2. Check that there is no break in the wiring loom. 3. Check that the gas valve has not shorted or is in open circuit. 4. Check voltage to the wiring loom to gas valve. 5. Check the control board if board failure. 5.8 Seven Flashes Over Temp Lockout Reason Too many overheats activations in latest heat cycle Overheat activation continues longer than overheat fan and cool down Service Check List: Please refer to overheat conditions in this manual. 5.9 Eight Flashes Frequency Lockout Reason Supply frequency outside operating limits Microprocessor clock outside operating limits The frequency check determines that the operating frequency of the micro-controller internal clock is correct. Comparison against the known mains frequency signal, being 24v AC 50Hz, shall be used to make this determination. The duration of this test shall be approximately 0.5 seconds A failure in the clock circuit shall enter the unit into lockout and flash the eight flash on the LED status light. Service Checklist 1. Check power supply. 2. Check polarity at power point. 3. Check transformer voltage. 4. Control board failure. 281 Issue 1 - Service Manual - BX3 21

5.10 Nine Flashes - Flame Lockout Invalid Flame Reason Flame sense hardware fault. Control board start up safety check failure. Service Checklist 1. Check power supply. 2. Check polarity at power point. 3. Check transformer voltage. 4. Check flame sensor. 5. Hardware fault during start up operation. 5.11 Ten Flashes False Flame Reason Invalid flame sensed during safe start check or IDLE hardware fault. Detection of flame signal at power-up, while IDLE, or prior to ignition shall cause the unit to enter a volatile lockout and flash ten times on the status LED. Detection of the flame signal variation indicative of a grounding fault shall cause the unit to enter a volatile lockout. Service Checklist 1. Check power supply. 2. Check polarity at power point. 3. Check transformer voltage. 4. Check over heat switch is faulty. 5. Gas valve passing gas. 5.12 Eleven Flashes - SafeStart Lockout Reason Main valve safeguard too slow or failed to activate hardware fault. Confirmation that the secondary safeguard hardware timing circuit is within tolerance. Measurements are made by the micro-controller concerning the ability of the flame circuit to operate the secondary safeguard circuit, and that the timing is within allowable tolerance. The upper limit is the specified flame establishment time. If the safeguard circuit fails verification, the unit shall enter lockout and shall flash eleven flashes on the status LED. Service Checklist 1. Check power supply. 2. Check polarity at power point. 3. Check transformer voltage. 4. Control board failure. 5.13 Twelve Flashes Secondary Fafeguard Timing Fault 281 Issue 1 - Service Manual - BX3 22

Reason SafeStart checks did not complete in time, no hardware fault recorded. Service Checklist 1. Check power supply. 2. Check polarity at power point. 3. Check transformer voltage. 4. Control board failure. 5.14 Three Slow Flashes Ground Fault Lockout Reason Flame variation detected due to poor earth connection to chassis ground. There has been a false flame that is detected during a power reset turning on and off. There has been a false flame has gone away after an over heat condition has been cleared. Service Checklist 1. Check the earthing system. 2. Check the control board. 3. Check the flame sensor. 4. Check the gas valve. 5. Check the flame roll out switch. 6. Check the flame roll out switch loom. 5.15 Three Slow Flashes - Ground Fault Lockout Reason Flame variation detected due to poor earth connection to chassis ground. There has been a false flame that is detected during a power reset turning on and off. There has been a false flame has gone away after an over heat condition has been cleared. Service Checklist 1. Check the earthing system. 2. Check the control board. 3. Check the flame sensor. 4. Check the gas valve. 5. Check the flame roll out switch. 6. Check the flame roll out switch loom. 281 Issue 1 - Service Manual - BX3 23

5.16 Three Slow Flashes - Ground Fault Lockout Reason Flame variation detected due to poor earth connection to chassis ground. There has been a false flame that is detected during a power reset turning on and off. There has been a false flame has gone away after an over heat condition has been cleared. Service Checklist 1. Check the earthing system. 2. Check the control board. 3. Check the flame sensor. 4. Check the gas valve. 5. Check the flame roll out switch. 6. Check the flame roll out switch loom. 281 Issue 1 - Service Manual - BX3 24

6.0 MAIN COMPONENTS SERVICING This section contains the procedures for checking and adjusting (if necessary) main components of the heater. This may be required due to a failure or a routine service. 6.1 Gas Valve Servicing The diagram below indicates the measurement and adjustment locations. If adjustment to the gas valve is required, remove the cap screw and adjust via the pressure regulator adjustment screw. VR8215S Direct ignition combination gas controls Gas valve checking and adjustment (only if required). To check for correct gas valve settings and operation the following should be performed, and adjustments made when necessary. Inlet Pressure Measurement Remove the gas inlet tap and replace with a pressure test point. Connect a suitable manometer to the test point. Turn on the heater and wait for the flame proving period to finish. Check that the inlet gas pressure is between 1.1 kpa to 3.5 kpa. Pressures below this level can result in insufficient gas pressure for combustion. If this is the case then this situation should be rectified. Remove the manometer and remove the test point. Replace the gas inlet tap and test for gas leakage. Note: Please use an approved sealant. 281 Issue 1 - Service Manual - BX3 25

Low Inlet pressures Gas Valve Servicing (cont) It is possible that low inlet pressure can cause: Unreliable ignition if the inlet pressure is below 0.80 kpa at the time of ignition. Underrated heat output Burner Pressure Measurement 1. Loosen the burner pressure test point screw, on the gas valve in the location shown in the diagram, and connect a suitable manometer immediately. 2. Turn on the heater and wait for the flame proving period to finish. 3. Check the burner gas pressure and if it requires adjusting please follow the below steps. 4. Unscrew the pressure regulator adjustment cap. 5. There is a adjustment screw under the cap which will adjust the burner pressure. 6. Clockwise will increase the gas pressure. 7. Anticlockwise will decrease the gas pressure. 8. The table below shows the gas pressure for each unit. 9. Turn the unit off and remove the manometer and unscrew the test point and rescrew the cap back into its place. 10. Please ensure there is no leaks on each of the pressure tap screw. Note: Please use an approved sealant. For gas pressure please refer to technical information sheet. 281 Issue 1 - Service Manual - BX3 26

6.2 Combustion Fan Servicing General Service 1. Check that the motor s shaft spins freely. 2. While in operation during a prepurge, check for any unusual noise, such as bearing or scraping noise. If there is any suspicion of an underperforming combustion fan or that the entire system is resulting in low vacuum pressure, the following should be performed: 1. Isolate the heater s power supply. 2. Check the motor s winding resistance with the wire looms removed. 3. Re-insert the motor s wiring loom. 4. Connect a manometer into the combustion fan vacuum pressure hose to measure the vacuum pressure just prior to the combustion fan. 5. Re-apply power to the heater and force it into an overheat mode to power up the combustion fan. (Warning: Remember the motor operates with 240 Vac.) 6. Measure the combustion fan vacuum pressure, and ensure that it reaches the value as specified in the table below. Combustion Fan Motor Fime Winding Resistance @20 o C Resistance Reading 24.3 Ohms If the vacuum pressure is below the specified values: 1. Check that the flueing is within the allowable specifications. 2. Look for any physical causes of underperformance such as the buildup of soot or silicon in the combustion fan housing or flue pipe. Clean if necessary. Servicing while removed It may be required to remove the combustion fan to inspect it totally.(refer to section 7.2 C for removal procedure of the combustion fan). For air pressure signals please refer to technical information sheet. 281 Issue 1 - Service Manual - BX3 27

6.3 Spark Igniter Servicing Isolate the heater power and gas supply from the unit. Checking the spark igniter 1. Unscrew the spark igniter away from the burner 2. Check spark igniter electrode, lead and plug connection 3. Clean igniter probe and make sure there is a spark gap of approx ±2mm. 4. Then reassemble. Checking spark igniter location relative to burner face 1. Remove the burner assembly as described in removal procedure 5. 2. Measure the distances as shown in the diagram below. 3. Installation is a reversal of the removal procedure. 11±1.5 mm 8.5±1.5 mm Sparker probe end is in alignment with burner centreline ±2 mm. 6.4 Flame Sensor Servicing Isolate the heater power and gas supply from the unit. Checking the flame sensor 1. Check that the flame sensor rod is clean, located correctly and the lead and plug connection is in good condition. 2. Reassemble. Checking flame sensor location relative to burner face 1. Remove the burner assembly as described in removal procedure 5 2. Measure the distances as shown in the diagram below. 3. Installation is a reversal of the removal procedure. 12±2 mm 11±2 mm 281 Issue 1 - Service Manual - BX3 28

6.5 Pressure Switch Servicing 1. Isolate the heater power and gas supply from the unit. 2. Tap into the pressure switch line with a PVC T-Piece with a suitable manometer. 3. Check that the pressure switch is opening within the limits specified below as follows: 4. Measure the vacuum pressure and make sure the vent hole and bleed hole are clear of any foreign material. 5. Make sure the hoses are free of condensation. 6. Check the hoses leading to the pressure switch are clear of foreign material 7. Reassemble. Vent Hole (2.3 mm) Bleed Hole (0.4 mm) Unit BX315 BX320 BX326 Pressure switch (Opens) 115pa 80pa 50pa 6.6 Main Fan Assembly Servicing Internal Models 1. Turn the unit OFF and isolate the power supply. 2. Remove the panel on the fan compartment gas entry side of the heating unit so there is access to the fan motor assembly. 3. Remove fan housing from cabinet. 4. Remove fan assembly from housing. 5. Clean impellor and motor. 6. Clean housing. 7. Reassemble. 8. Check all wiring cables and plug connections. Installation is a reversal of the removal procedure. 281 Issue 1 - Service Manual - BX3 29

6.7 Unit Operation 1. Check power supply lead is in good condition. 2. Check all gas connections are good and do not leak. 3. Check the wall control wiring connection at the unit is in good condition. 4. Check the maximum burner pressure at the test point provided on the gas valve. 5. Check the duct system airflow distribution, balance and adjust as required. 6. Check the unit s selected 3 speed fan is appropriate for optimum heat output for the application. 281 Issue 1 - Service Manual - BX3 30

7.0 DISMANTLING PROCEDURES Before any of the following assemblies or components can be removed, it is important to isolate the heater s power supply. The lid of the heater will also have to be removed by removing 2 screws at each end of the lid. 7.1 Burner Assembly Removal 1. Turn the gas isolation valve off and isolate the heater s power supply 2. Unscrew the hose clamp off the combustion fan flue pipe. Remove the flue cowl off the front of the unit and slide the flue pipe out of the unit. 3. Remove the gas valve loom; spark igniter lead, flame sensor lead and flame rollout switch loom and plate. 4. Remove the gas inlet pipe off the gas valve and move the piping enough to enable the burner assembly to be removed when ready. 5. Remove the 2 screws that hold the flame rollout switch plate then remove the plate away from the gas manifold. 6. Remove the other 2 screws holding the burner manifold to the burner assembly and remove the assembly. 7. Remove the 4 screws holding the burner assembly to the heat exchanger main plate. 8. The burner assembly can now be removed. Installation is a reversal of the removal procedure with attention to the following points: 1 Ensure that the gas inlet feed-tube is retightened and checked for leaks. 2 Ensure that all looms, wires and leads are not damaged along their length and at the connectors. 7.2 Gas Manifold Assembly Removal 1. Turn the gas isolation valve off and isolate the heater s power supply. 2. Unscrew the hose clamp off the combustion fan flue pipe. Remove the flue cowl off the front of the unit and slide the flue pipe out of the unit. 3. Remove the gas valve loom from the gas valve. 4. Remove the gas inlet feed-tube off the gas valve. 5. Remove the 2 screws that hold the flame rollout switch plate then remove the plate away from the gas manifold. 6. Remove the 2 screws holding the gas manifold to the burner assembly. 7. The gas manifold assembly can now be removed. Installation is a reversal of the removal procedure with attention to the following points: 1. When re-inserting the assembly, ensure that the injectors are inserted into the ring on the top of the burners correctly. Ensure that the gas inlet feed-tube is retightened and checked for leaks. 2. Ensure that the gas valve loom is not damaged along its length and at the connector. 281 Issue 1 - Service Manual - BX3 31

7.3 Gas Valve Removal 1. Turn the gas isolation valve off and isolate heater s power supply 2. Disconnect the gas valve loom. 3. Remove the gas inlet feed-tube off the gas valve. 4. Remove the gas valve from the burner manifold by unwinding it in an anti-clockwise direction. 4. Remove the brass adaptor on the gas valve inlet side of the gas valve if the valve is to be replaced. Installation is a reversal of the removal procedure with attention to the following points: Clean any threads of excessive gas thread sealant, which are to be re-assembled If a new gas valve is to be fitted, apply gas thread sealant to the brass adaptor and fingertighten onto the gas valve. Apply gas thread sealant to the burner manifold feed tube nipple and screw on the gas valve, and then tighten. Check for leaks on both sides of the gas valve while in operation. If a new gas valve is fitted, ensure that it is reset, including the gas pressure, as outlined in the technical information sheet regarding the unit pressures. 7.4 Pressure Switch Assembly Removal 1. Isolate the heater s power supply. 2. Remove the hose from the pressure switch. 3. Remove the electrical wires from the pressure switch. 4. Remove the pressure switch fastening screw if the pressure switch is to be replaced. Installation is a reversal of the removal procedure with attention to the following points: Ensure all wiring connections are positively located and that no looms have been damaged. Ensure the pressure hose is connected as far as possible to the body of the pressure switch nipple. 7.5 Combustion Fan Removal Method 1 Partial fan removal 1. Isolate the heater s power supply. 2. Remove the electrical leads off the combustion fan. 3. Remove the flue cowl off the flue pipe that is on the external wall of the heater 4. Unscrew the hose clamp that holds the flue pipe onto the combustion fan outlet. 5. Remove the flue pipe and rubber silicone connector. 6. Remove 3 screws which fasten the combustion fan down to the combustion fan box. 7. Pry the combustion fan off the box, which will still be fastened by the sealing heat proof silicon. Installation is a reversal of the removal procedure with attention to the following points: 1. Clean both surfaces to be re-mated together. Apply sufficient (but not excessive) silicon to the combustion fan s mating surface 281 Issue 1 - Service Manual - BX3 32

Method 1 Partial fan removal 1. Isolate the heater s power supply. 2. Remove the electrical leads off the combustion fan. 3. Remove the flue cowl off the flue pipe that is on the external wall of the heater 4. Unscrew the hose clamp that holds the flue pipe onto the combustion fan outlet. 5. Remove the flue pipe and rubber silicone connector. 6. Remove 3 screws which fasten the combustion fan down to the combustion fan box. 7. Pry the combustion fan off the box, which will still be fastened by the sealing heat proof silicon. Installation is a reversal of the removal procedure with attention to the following points: 1. Clean both surfaces to be re-mated together. 2. Apply sufficient (but not excessive) silicon to the combustion fan s mating surface. 281 Issue 1 - Service Manual - BX3 33

7.6 Main Fan Assembly Removal 15,20 & 26Kw units 1. Turn the unit OFF and isolate the power supply. 2. Remove the 7 screws holding the top plate on the fan compartment 3. Remove the screw that holds the wiring loom onto the top of the fan compartment. 4. Remove the wiring loom from the fan speed connector block. 5. Remove the fan top plate away from the fan compartment and ensure that the wiring looms are not restricting the removal of the plate until you expose the fan motor assembly. 6. Slide the fan motor upwards and away from the fan compartment. 7. Remove fan motor plate from the fan scroll. (See below for Motor and play removal). Installation is a reversal of the removal procedure. Removal of the fan assembly. Unscrew the screws holding the top plate down and then remove carry handle. Remove the screw that holds the wiring loom onto the top of the fan compartment and the wiring loom from the fan speed connector block. Once the fan motor is exposed then slide the fan motor upwards and away from the fan compartment 281 Issue 1 - Service Manual - BX3 34

Main Fan Assembly Removal (Cont) Motor and plate removal Remove the 7 screws that attach motor plate to the fan scroll then remove the motor plate, motor and fan wheel assembly from the fan scroll. Remove the fan from the motor by loosening the grub screw from the motor shaft. If the fan wheel is ceased onto the motor shaft then use WD-40 and a puller may be required. The motor may be removed from the motor plate if required by removing the bolts and nuts that secure the motor to the motor stator brackets. 7.7 HCDSI24-1 Electronic Control Board Removal 1 Isolate the heater s power supply. 2 Remove the spark igniter lead from the PCB assembly. 3 Remove all other electrical connections from the PCB assembly. 4 Remove the 4 screws that secure the HCDSI 24-1 to the top plate of the fan compartment. WARNING: Care should be taken to prevent any damage to the wiring and PCB. Installation is a reversal of the removal procedure with attention to the following points: Ensure all wiring connections are positively located and that no looms have been damaged. 7.8 240 to 24 Volt Transformer Removal 1. Isolate the heaters power supply. 2. Remove all inter-connecting conductors. 3. Remove the 2 screws that secure the transformer to the top plate of the fan compartment Installation is a reversal of the removal procedure with attention to the following points: Nominal Voltage/ Maximum Current 230 VAC / 1.75 A 1.75A Transformer Secondary Voltage (No Load) (Blue Yellow) @ 230 VAC Secondary Voltage (With Load) (Blue -Yellow) @ 230 VAC 24 28.5 VAC 24± 3% VAC Resistance reading on primary wiring @ 20 0 C Resistance reading on Secondary @ 20 0 C 63.6 Ω 1.45 Ω 281 Issue 1 - Service Manual - BX3 35

7.9 Heat Exchanger Removal 1. Remove from the top. 2. Isolate the heater s power supply. 3. Remove the main wiring looms in the heater combustion chamber. 4. Unscrew the hose clamp off the combustion fan flue pipe. Remove the flue cowl off the front of the unit and slide the flue pipe out of the unit. 5. Remove the burner manifold. 6. Remove the pressure switch hose. 7. Remove the burner assembly. 8. Remove the 8 screws that hold the heat exchanger to the frame of the unit. 9. Remove the 2 screws that hold the side panel flue end on the external part of the unit and pull away from the unit. This will expose the entire gas feed pipe. 10. Unscrew the gas feed tube off the gas cock and then remove away from the unit. 11. Then raise the heat exchanger making sure the heat exchanger has been fully removed. 281 Issue 1 - Service Manual - BX3 36

Installation is a reversal of the removal procedure with attention to the following points: Clean both surfaces to be re-mated together. Ensure all wiring connections are positively located and that no looms have been damaged. When re-inserting the burner assembly, ensure that the injectors are inserted into the ring on the top of the burners correctly. Ensure that the gas inlet feed-tube is retightened and checked for leaks. Ensure that the gas valve loom is not damaged along its length and at the connector. Heat exchanger removal (Photos) Screw locations (7 off) securing heat exchanger. 281 Issue 1 - Service Manual - BX3 37