Baxi Neta-tec Combi GA Range Quick start guide

© Baxi Heating UK Ltd 2012
Neta-tecCombiGARange
Duo-tec2CombiGARange
Megaflo2SystemGARange
Gas Fired Wall Mounted Condensing
Combination & System Boilers
Appliance Technical Guide
Service Engineer Edition

2© Baxi Heating UK Ltd 2012
1.0 Gas Adaptive System 3
2.0 Combi C.H. Sequence of Operation 4
3.0 Combi D.H.W Sequence of Operation 5
4.0 System C.H. Sequence of Operation 6
5.0 Commissioning Function 7
6.0 Service Due Function 9
7.0 Checking the Combustion 10
8.0 Combustion Re-calibration 11
9.0 Gas Type Selection 15
10.0 Information Menu 16
11.0 Error History 17
12.0 Errors & Sub-codes 19
13.0 P.C.B. & R.D.S. 21
14.0 Electronic Gas Valve 22
15.0 Hydraulics 23
16.0 Internal Wiring 26
17.0 Electrical Measurements 29
18.0 Parts Matrix 30
19.0 E133 Flow Chart 31
20.0 Commissiong Procedure & Errors 32
21.0 Additional Information 33
22.0 Pages for Notes 34
Page
Contents
Appliance Technical Guide
This Appliance Technical Guide contains information to enable
diagnosis of faults, interpretation of error codes, identification
of key componets and the performing of commissioining,
calibration and combustion checking.
Models covered:-
• Baxi Neta-tec Combi
• Baxi Duo-tec 2 Combi
• Baxi Megaflo 2 System
Note:These buttons
inactive on System
models:-
If only the symbol is
displayed on System
models the boiler will
not operate. Press the
button until the
symbol appears.

3
© Baxi Heating UK Ltd 2012
The Gas Adaptive System
The Baxi GA range of boilers are fully ‘Gas Adaptive’.This means the system automatically monitors the flame and adjusts
the gas valve to achieve the correct combustion at all times.
Explanation of Set Flames on GA
The Set Flame is a value that is used to achieve the desired combustion and is set at either during manufacture or by an
engineer on site. The value of this is different for each model because of fan speeds, mixers, nozzles, heat exchangers etc.
hence each model has different Set Flames.
This value relates to the ionization signal (e.g. 35 = 350 kOhms), and it simply tells the boiler what ionization it should
achieve at that fan speed.
If it is set incorrectly the boiler will always try to achieve that signal. It must be set correctly at manufacture, and by an
engineer if any gas carrying parts or R.D.S. are changed, to achieve 9.0% +-0.2 CO2 on N.G. (10.5% +-0.2 CO2 on N.G. )
The adjustable Set Flames are at three fixed fan speeds:-
00 (min)
IGN (ignition) Displayed as 33, 41 etc. It is a % of maximum fan speed or ‘power’.
100 (max)
From these three points, a curve is drawn and the values for the entire RPM range are calculated.
When the Set Flame is changed at one of the fan speeds above, the RPM will always stay the same, but the PCB will send a
signal to the valve to open or close the solenoid to alter the gas flow so that the ionization signal matches the Set Flame
value just inputted.
As the ionization signal changes, so does the combustion.
Boiler Cycle: From Factory to Installation
Installed
Commissioning
Function
Service Due - 1
Service Due - 2
Boiler set
automatically to
achieve 9.0% CO2
Boiler fitted by installer
Before use boiler must
complete C.F.
After 11 months ‘Sd’
shown on boiler
display
After 11 months ‘Sd’
shown on boiler
display
‘SD’ function reset at annual service
1.0 Gas Adaptive System
Manufactured & Set
on N.G.

C.H. Demand
4© Baxi Heating UK Ltd 2012
Pump On
Diverter Valve C.H.
Position
Fan On RPM Check - OK E160
Gas Valve Start
Sequence
Gas Valve Opens
Spark
Ignition
Flame On
Flame Stabilization
Full C.H. Rate
No Ignition E133
Reset
5 Attempts -
Ignition
Achieved
Loss of
Flame
E128
Reset
5 Seconds
Stabilization
Boiler Operating
2.0 Combi C.H. Sequence of Operation
Pump Check by
Water Pressure - OK E430
Ye s
No
Ye s
No
Ye s
No
12 Attempts -
Ignition
Achieved
No
Ye s
Combi Models

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© Baxi Heating UK Ltd 2012
D.H.W. Demand
Diverter Valve
D.H.W. Position
Gas Valve Start
Sequence
Gas Valve Opens
Spark
Flame On
3.0 Combi D.H.W. Sequence of Operation
Pump On Pump Check by
Water Pressure - OK E430
Ye s
No
Fan On RPM Check - OK E160
Ye s
No
Ignition No Ignition E133
Reset
5 Attempts -
Ignition
Achieved
Ye s
No
Flame Stabilization
Full D.H.W Rate
Loss of
Flame
E128
Reset
5 Seconds
Stabilization
Boiler Operating
12 Attempts -
Ignition
Achieved
No
Ye s
Combi Models

6© Baxi Heating UK Ltd 2012
C.H. Demand
Pump On Pump Check by
Water Pressure - OK
Gas Valve Start
Sequence
Gas Valve Opens
Spark
Ignition
Flame On
Flame Stabilization
Full Rate
Loss of
Flame
5 Seconds
Stabilization
Boiler Operating
4.0 System C.H. Sequence of Operation
E430
Ye s
No
No Ignition E133
Reset
5 Attempts -
Ignition
Achieved
Ye s
No
Fan On RPM Check - OK E160
Ye s
No
E128
Reset
12 Attempts -
Ignition
Achieved
No
Ye s
System Models

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© Baxi Heating UK Ltd 2012
The Commissioning Function (CF) - Description
The CF is a one off forced function that is activated on the first power up of the boiler after it has left the factory.The boiler
cannot be operated unless the CF has been completed and the CF can be activated only once.
There are two stages to the CF - De-aeration of the system followed by a Gas Type Check.
De-aeration
This function operates the pump and the diverter valve moves from DHW to CH periodically to purge the system of air.
It ensures maximum evacuation of air and prevents damage to the heat exchanger coils at initial fire up.This takes
approximately 7 minutes to complete.
Gas Type Check
This automatically follows the de-aeration function and checks the flame signal to determine if the gas supply is NG or LPG.
It is done by first running at IGN rate, then at full power for the final stage. From these two speeds two values are measured
which are used to recognize the gas type being supplied.
IMPORTANT:When checking at full power, the combustion can go higher than normal for a few seconds, therfore it is not
advisable to insert the analyser probe into the flue sampling point to measure combustion, as saturation may occur and
affect subsequent readings.This stage takes approximately 4 minutes to complete.
The total time for the CF is between 10 and 12 minutes.
Activation of Commissioning Function (CF) from initial Power On
See page 32 for the flow diagram.
Once power is supplied to the boiler the display will show ‘000’ which indicates that the CF needs to be activated.
• Press and hold the ‘CH +ve’ and the ‘ip’ button, together for 6 seconds
• ‘312’ should be displayed and the boiler is now performing the de-aeration cycle
• After approx 7 minutes, the boiler will fire and the Gas Type check cycle will start
• The boiler will remain at a reduced rate for approx 3 minutes, in the final minute it will ramp to ‘100’, during this
time the boiler temp will be displayed. It is advised to open a DHW tap to dump the heat.
• Once the Gas Type check has finished, the display will show what type of gas the boiler is connected to:
• If it is natural gas, it will flash ‘NG’ for a few seconds and then be ready to operate
• If it is LPG, it will flash ‘LPG’ and this will need to be confirmed by pressing the ip button for 6 seconds. All
software values are automatically modified and the boiler is ready to use
If the boiler display shows ‘LPG’ when NG is being supplied, it can be cancelled by pressing the ‘ip’ and reset ‘R’ button
together for 4 seconds.
When there is an error present (e.g. Low Water Pressure – E118) it must be rectified before the CF can be started or
completed.
If there is an interruption to CF it will start again. If de-aeration has been completed, it will start from gas type check.
5.0 Commissioning Function

8© Baxi Heating UK Ltd 2012
Commissioning Function (CF) Mini-Calibration if E133 in Commissioning Mode
If during Commissioning Function the boiler fails to light and goes to E133 then a “mini-calibration” can be performed
within the CF Function (assuming the gas supply has been checked).
• With the display showing ‘000’ and before the Gas Type check, press and hold the reset ‘R’ and ‘CH -ve’ buttons for 6
seconds, followed by the ‘ip’ button.
• The display should now show the ignition speed and calibrate. It will go to ‘100’ briefly then back to ‘000’
Commissioning.
• To activate the Gas Type Check, press and hold the ‘ip’ and ‘CH +ve’, as normal and the boiler will now complete
the Gas Type Check.
IMPORTANT NOTE:
IT IS NOT POSSIBLE TO CALIBRATE A NEW GAS VALVE WHILST IN COMMISSIONING MODE !
Manual De-aeration Function (312)
This function can be activated manually, for example in instances when a radiator or heat exchanger has been changed and
thus the system needs to be purged of air.
• Press and hold the ‘ip’ and ‘CH -ve’ buttons for 6 seconds.
• The display will show ‘312’ and the De-aeration function activated.
• It will be active for 10 minutes.
• To disable, either press and hold the ‘ip’ and ‘CH -ve’ for 6 seconds or isolate the power to the boiler.
5.0 Commissioning Function (cont.)

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© Baxi Heating UK Ltd 2012
Service Due Function (SD) - Description
When this function is activated ‘Sd’ is displayed after a pre-determined time (Factory Set at 11 months) informing the user
that the 12 month service is due shortly. It is only active whilst there is power to the boiler. If power is interrupted the
counter continues from where it stopped previously.
The boiler continues to work as normal and the display flashes 'Sd' for 3 seconds, every 10 seconds.
It can be reset, disabled and Service Time changed by alteration of parameters.
IMPORTANT NOTE: DO NOT ADJUST ANY OTHER VALUES OR PARAMETERS AS IT WILL AFFECT THE
OPERATION OF THE BOILER
To reset the SD Function
• Once the annual service is complete the SD Function must be reset so the next service can be indicated.
• Press and hold the ‘CH -ve’ and ‘CH +ve’ buttons together for 6 seconds to enter the ‘TSP Menu’. P01 will be
displayed.
• Use ‘CH +ve’ to scroll to ‘P22’.
• Press the ‘ip’ button to toggle into the ‘P’ value.
• Change ‘00’ to ‘15’ (15 is the SD counter reset code).
• Press the ‘ip’ button to toggle back to to lower parameter menu.
• Press the reset button ‘R’ to exit the ‘TSP’ menu.
The next SD message will be displayed in 11 months.
To disable or change the SD Function Time Period
• Press and hold the ‘CH –ve’ and ‘CH +ve’ buttons together for 6 seconds to enter the ‘TSP Menu’. P01 will be
displayed.
• Use ‘CH +ve’ to scroll to ‘P22’.
• Press the ‘ip’ button to toggle into the ‘P’ value.
• Change ‘00’ to ‘22’ (22 is the code to access the higher parameters - P41 and above).
• Press the ‘ip’ button to toggle back to lower parameter menu.
• Use ‘CH +ve’ to scroll to ‘P50’.
• Press the ‘ip’ button to toggle into the value for ‘P50’.
• The value range is 6….25:-
6….24 = months elapsed before ‘Sd’ is displayed.
25 = function disabled.
• Choose the desired value and press the ‘ip’ button to confirm.
• Press the reset button ‘R’ to exit the ‘TSP’ menu.
6.0 Service Due Function
!

10 © Baxi Heating UK Ltd 2012
Checking the Combustion - F304
At each service the combustion must be checked at three fan speeds:- ‘00’,‘IGN’ and ‘100’.
00 = Minimum
IGN = Ignition Speed (different for each model)
100 = Maximum Speed (D.H.W. power for Combi)
To check the combustion at these 3 speeds Function 304 must be activated.
To activate, press and hold the ‘ip’ and ‘CH +ve’ buttons together for 6 seconds.
‘304’ should be displayed and then the boiler will run at maximum when ‘100’ will be displayed. Allow a few moments for
the boiler to stabilize then measure the combustion.
To choose the next fan speed, press the ‘CH –ve’ button - the Ignition Speed will be displayed.To set at minimum press the
‘CH –ve’ again.‘00’ will be displayed.
To de-activate this function, press and hold ‘ip’ and ‘CH +ve’ for 6 seconds or isolate power to the boiler for several seconds.
Note: If at ‘100’ the boiler temperature reaches 85°C, the burner will be extinguish and it will start again.To prevent this
from happening, open one or two D.H.W. taps whilst in F304 and the boiler will automatically dump the heat through the
D.H.W. circuit. In the case of System models it is recommended that any stored hot water is depleted prior to
commencement.
Limited Combustion Adjustment - F304
• A limited adjustment of the combustion can be performed whilst Function 304 is activated.
• By pressing the ‘ip’ button at any of the three fan speeds above an adjustment value is accessed.This adjustment is
limited in that a deviation of only -3 or +3 from the original value of 0 is permitted.The combustion can be
altered by approximately +/- 0.6% in this mode.
• Changing the value by 3 increases or decreases the CO2 value by approximately 0.6%.
• Positive adjustment equates to richer combustion and negative adjustment results in weaker combustion.
• Once the combustion has been changed, press the ‘ip’ button to toggle back to the fan speed and now, by
pressing the ‘CH +ve’ or ‘CH -ve’, the fan speed can be changed.
• Once completed press and hold the ‘ip’ and ‘CH +ve’ buttons for 6 seconds to de-activate Function 304.
7.0 Checking the Combustion

11
© Baxi Heating UK Ltd 2012
8.0 Combustion Re-calibration
Combustion Re-calibration
Each boiler is calibrated during manufacture and set during F.F.T. (Final Function Testing).This sets the Fan and E.G.V.
(Electronic Gas Valve) to the rest of the system. Combustion at F.F.T. is set at 9.0% +/- 0.2% on N.G.
The system must be re-calibrated by the engineer to the procedure below if any of the following are changed:-
• Gas Valve
• R.D.S. (Removable Data Stick)
• Burner
• Fan
IT IS ESSENTIAL THAT THE
CALIBRATION PROCESS IS
STARTED WHEN THERE IS NO
DEMAND !
Press the ‘CH -ve’ and reset ‘R’
buttons together for 6 seconds.
‘On’ will be displayed and within 2
seconds of this showing press the ‘ip’
button.
If ‘303’ is displayed, the time window
to press the ‘ip’ button has been
missed. Power down at the fused spur
and start again.
DO NOT TURN ON THE
ANALYSER PUMP WHILST THE
BOILER IS CALIBRATING AS THE
INTERNAL CELL MAY BECOME
SATURATED !
Remove the boiler front door and
connect the manometer to the Inlet
Test point on the Gas Valve.
After the ‘ip’ button is pressed the
Ignition Fan Speed (as % of maximum)
will be displayed. Each model is
different (e.g. 33GA is ‘41’).
The boiler software will now search
for the appropriate ignition curve to
light with, usually curve 3 or 4.
To G.V. Inlet
Test Point
To G.V. Inlet
Test Point
After several seconds ‘100’ will be
displayed, indicating that the fan is a
maximum speed. It may be necessary
to put a D.H.W. demand on the
system if the temperature exceeds
85°. Check the gas inlet pressure has
not dropped below 16mb.
The boiler will remain at ‘100’ until
stabilization is achieved - up to 3
minutes.
To G.V. Inlet
Test Point
>16mb
Combined Analyser/Manometer

12 © Baxi Heating UK Ltd 2012
After stabilization at maximum (‘100’)
the boiler will revert to ignition fan
speed to stabilize at this rate as well,
taking up to 3 minutes.
To G.V. Inlet
Test Point
After stabilization at ignition fan speed
minimum power will be automatically
selected, ‘00’ being displayed.
Stabilization at this speed will take up
to 2 minutes.
To G.V. Inlet
Test Point
Once calibration is complete the
flame, tap & radiator icons will flash
and the display alternate between ‘00’
and a value. This value is the ‘Set
Flame Value’.
The Set Flame controls the ionization
signal and thus the combustion level.
Each fan speed has an adjustment. The
Set Flame determines what the boiler
can achieve so it is essential to have
correct combustion.
INSERT THE ANALYSER PROBE
INTO THE FLUE SAMPLING POINT
To Flue
Sampling Point
Pressing the ‘CH -ve’ or ‘CH +ve’
buttons changes the Set Flame value.
Increasing the value weakens
combustion, decreasing it makes the
combustion richer.
To Flue
Sampling Point

13
© Baxi Heating UK Ltd 2012
Once combustion is set to 9.0% press
the ‘ip’ button.
The display will alternate between the
fan speed (‘00’ or minimum in this
case) and the boiler temperature.
°C
To Flue
Sampling Point
To select the next fan speed press the
‘CH +ve’ button.
‘33’ will be displayed, indicating
ignition speed.
°C
To Flue
Sampling Point
To view the Set Flame value at that fan
speed press the ‘ip’ button.
The display will alternate between the
ignition fan speed (‘33’) and the Set
Flame value (‘38’ in this example).
Change the Set Flame value to achieve
9.0% CO2 by pressing ‘CH -ve’ or
‘CH +ve’.
Press the ‘ip’ button followed by
‘CH +ve’ to change to maximum fan
speed (‘100’). Press the ‘ip’ button to
display the Set Flame value. The value
can be changed by pressing ‘CH -ve’
or ‘CH +ve’ buttons to achieve
9.0% CO2.
To Flue
Sampling Point
Once combustion has been checked,
adjusted where necessary, and the
readings recorded at each fan speed
press reset ‘R’ button to escape the
calibration function - ‘ESC’ will be
displayed.
To Flue
Sampling Point

14 © Baxi Heating UK Ltd 2012
Remove the pressure tube from the
Gas Valve Inlet Test Point. Tighten the
screw.
Replace the front door, ensuring it is
secured by the screws previously
removed.
Insert the analyser probe in the Air
Sampling Test Point. Replace the plug
in the Flue Sampling Test Point.
To Flue
Sampling Point
Press the ‘ip’ button and ‘CH +ve’ for
6 seconds. ‘304’ will be displayed and
the boiler will operate at maximum fan
speed. ‘100’ will be displayed,
alternating with the boiler temperature.
Pressing ‘CH -ve’ button will change
the fan speed to Ignition, a further
press selecting minimum speed.
Check for recirculation at each fan
speed:- ‘100’, ‘33’* & ‘00’.
* ‘33’ is typical a value
Once the recirculation check is
complete, either press the ‘ip’ and
‘CH +ve’ buttons for 6 seconds or
isolate the power at the used spur and
then re-instate it.
To Flue
Sampling Point
°C

15
© Baxi Heating UK Ltd 2012
Gas Type - L.P.G. & N.G.
By gaining access to the ‘TSP’ (Transparent Slave Parameters) Menu the Gas Type can be adjusted, for example from L.P.G. to
N.G. in rural areas when mains N.G. is provided subsequent to installation.
Note: If the boiler is to be installed on an L.P.G. supply from new consult the information on page 7.
• Press and hold the ‘CH +ve’ and ‘CH -ve’ buttons together for 6 seconds
• ‘P01’ will be displayed alternating with its value (‘0’).
• Pressing the ‘CH +ve’ and ‘CH -ve’ buttons scrolls through the parameter list.
• Press ‘CH +ve’ until ‘P02’ is displayed.
• Press the ‘ip’ button to view the selected parameter.
• Pressing the ‘CH +ve’ and ‘CH -ve’ buttons modifies the parameter.
• P02 = 0 Boiler set for N.G.
• P02 = 1 Boiler set for L.P.G.
• Press the ‘ip’ button to safe the parameter value.
• Press the reset ‘R’ button to leave the TSP menu.The boiler temperature will be displayed - the boiler is ready
for use.
Once parameter P02 is set to the gas type required no calibration is necessary.The boiler will operate normally with the
new settings automatically adjusted.
Combustion Level & Setting Tolerance
N.G. = 9.0% CO2 +/-0.2%
L.P.G. = 10.5% CO2 +/-0.2%
Note:The tolerance of +/-0.2% is for setting puposes - a tolerance of +/-0.8% can be applied when checking.
The combustion is the same at each fan speed.
9.0 Gas Type Selection

16 © Baxi Heating UK Ltd 2012
Information Menu
By gaining access to the Information Menu a number of values can be viewed.The information can be used to diagnose
faults, e.g. the value of a sensor to check if it is open circuit or closed circuit
Press ‘ip’ for 1 second.
The display will alternate between the ‘0’i code (e.g. i 02) and its value.
To scroll down the list press the ‘ip’ button.
i 00: Error Subcode See table on page 18
i 01: C.H.Temperature °C
i 02: External Temperature (if present) °C
i 03: D.H.W. Temperature °C i 03 & i 04 are the same sensor
i 04: D.H.W. Temperature °C
i 05: Water Pressure bar
i 06: Return Temperature °C
i 07: Flue Temperature °C
i 08: Heat Exchanger Temperature °C
i 09: Not used
i 10: Not used
i 11: Not used
i 12: Not used
i 13: Not used
i 14: Not used
i 15: Not used
i 16: Not used
i 17: Fan Speed RPM RPM
i 18: num ic
This function operates for 3 minutes, or can be cancelled by pressing the reset ‘R’ button.
10.0 Information Menu

17
© Baxi Heating UK Ltd 2012
Reading Errors via the TSP Menu
The boiler records the most recent error codes, up to a maximum of 10.These can be viewed via the display.
Whilst the parameter lines are P32 through to P41, the display only shows the ‘C’ codes.
To gain access to the TSP menu:-
• Press and hold the ‘CH +ve’ and ‘CH -ve’ buttons together for 6 seconds
• ‘P01’ will be displayed.
• Pressing the ‘CH +ve’ to scroll through the parameter list.
• Error codes P32....P38.These errors do not require resetting, for example low system pressure.When the fault is rectified
the code automatically resets.
• Error codes P39....P41. Errors that must be manually reset, for example safety thermostat activated.
Once a parameter has been selected a series of numbers will be displayed. It is advisable to note them down as they
alternate between each other.The order is:-
• Error Number
• Error Code
• Counter for the same Error
• Days elapsed since Event
• System Status
• Phase Status
• C.H. Flow during Event
‘Counter for the same Error’
Number of times the same error has occurred.
‘Days Elapsed’
Number of days.‘45’ = 45 days since error.
‘System Status’
Operating Mode before the error.
0 Standby
1 D.H.W. Request
2 Controller Stop Function Active (F304)
3 C.H. Request
4 Preheat active
5 C.H. Frost Protection active
6 D.H.W. Frost Protection active
7 Pump Post circulation active
8 Overheating pump active
‘Phase Status’
Special Operating Mode before the error.
0 Standby
1 Pre-Purging Function active
03 Ignition Load purging between 1st and 2nd attempt
04 Ignition load 1st attempt
05 Operation Active
06 Lock Out
08 2nd Ignition Attempt
11 Ignition Load purging between 2nd and 3rd attempt
14 3rd Ignition attempt
15 Post Purging Function
16 Overheating Post Purging function
11.0 Error History

18 © Baxi Heating UK Ltd 2012
Reading Errors via the TSP Menu (cont.)
The display format is such that, for example, P32 will flash then the code, P32 again then the next code and so on.
For example:- P32...C01...P32...E06...P32...02...P32...000...P32...03...P32...05...P32...75°C.
The ‘C’ value is always the start of the sequence.
Error Table for Engineers
Table for recording errors:-
11.0 Error History (cont.)
P32 C01 E06 02 000 03 05 75°C
P33
P34
P35
P36
P37
P38
P39
P40
P41 C09
Error
Number
Error
Code Counter Days Elapsed
System
Status
Phase
Status
C.H.
Flow
Non-reset
Errors
Reset
Errors

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© Baxi Heating UK Ltd 2012
List of Errors & Sub-codes 12.0 Errors & Sub-codes
Gas valve connection fault
External probe fault
Differential water flow switch fault (still open)
Differential water flow switch fault (still closed)
Gas valve comand fault
Water refill activated
Maximum time of water refill
Central heating NTC sensor fault (s.c.)
Central heating NTC sensor fault (o.c.)
Return central heating NTC sensor fault (s.c.)
Return central heating NTC sensor fault (o.c.)
Flue NTC sensor fault (s.c.)
Flue NTC sensor fault (o.c.)
DHW NTC sensor fault (tank boiler) (s.c.)
DHW NTC sensor fault (tank boiler) (o.c.)
Incorrect calibration or obstruction in flue pipe
PCB to be set by the “Calibration Function”
Fan parameter out of range in autocalibration
Combustion test out of range in
autocalibration
Current out of range
Minimum gas valve current
Maximum gas valve current
No communication
Combustion test alarm during auto-setting
Precirculation alarm
Check the cable P.C.B./gas valve and gas valve plug
Check the sensor
Check the water flow switch
Check the water flow switch
Check the cable P.C.B./gas valve. Replace P.C.B. if necessary
Auto-Refill activated – motor energized
Auto-Refill open too long to fill – check system
Check the sensor
Check the sensor
Check the sensor
Check the sensor
Check the sensor
Check the sensor
Check the sensor
Check the sensor
Enable the Calibration Function and check flue for
obstruction
Enable the Calibration Function
Check the fan speed
Check the correct position and integrity of the sensing
electrode and cable
Check the correct position and integrity of the sensing
electrode and for flue recirculation. Enable the automatic
calibration function before replacing components.
Check the correct position and integrity of the sensing
electrode and for flue recirculation. Enable the automatic
calibration function before replacing components.
Check the correct position and integrity of the sensing
electrode and for flue recirculation. Enable the automatic
calibration function before replacing components.
Check cable between room unit and P.C.B. or R.F. link.
Failed the self check test during Calibration Function. Check
for re-circulation before changing Gas Valve
Check for correct circulation of water and pump
1
2
1
2
539
540
1
2
E09
E10
E12
E13
E15
E18
E19
E20
E20
E40
E40
E28
E28
E50
E50
E53
E55
E71
E72
E77
E78
E79
E83/84/85/86/87
E92
E109
Anomaly
Code
Internal
Code Anomaly Action
Note: (s.c.) = Short Circuit
(o.c.) = Open Circuit

12.0 Errors & Sub-codes (cont.)
20 © Baxi Heating UK Ltd 2012
Boiler max temperature exceeded for gradient
(possible sticking pump or air in the circuit).
Boiler max temperature exceeded for
overtemperature (possible sticking pump or air
in the circuit).
Safety thermostat sensor tripped.
Water pressure HIGH (> 2.9 bar).
Water pressure LOW (< 0.5 bar).
Water circulation falut (overtemperature).
Water circulation fault – Temp not increased
on the flow.
Water circulation fault.
Safety error for frequent loss of flame (12
times).
Safety error for frequent loss of flame with
max correction during the ignition during
Calibration Function.
Flue thermostat sensor tripped (lockout).
Gas supply fault.
Elapsed time gas valve open without gas (short
request in a short period).
Internal error.
Plausibility test (flow/return).
Fan fault.
Dry fire.
Wrong power supply electrical frequency (Hz)
Domestic Hot Water NTC sensor fault (s.c.)
Domestic Hot Water NTC sensor fault (o.c.)
Fault flame (parasitic flame).
Under voltage.
Water pressure temporary test.
Water pressure test failed.
Aluminium sensor fault (s.c.).
Aluminium sensor fault (o.c.).
Temperature rise too fast. Check correct circulation of the
water and pump.
Temperature overshoots Set Point by 20C. Check correct
circulation of the water and pump.
Check the sensor.
Check the water pressure.
Check the water pressure.
Check correct circulation of the water and pump.
Check correct circulation of the water and pump.
Check correct circulation of the water and pump
Check the sensing electrode and cable and for flue
recirculation. Enable the automatic calibration function
before replacing components.
Check the sensing electrode and cable and for flue
recirculation. Enable the automatic calibration function
before replacing components.
Check the thermostat, correct circulation of water and
pump.
Check the power supply, sensing electrode, spark electrode
and cable. Check flue recirculation. Enable the automatic
calibration function before replacing components.
Check the gas pressure, sensing electrode, spark electrode
and cable. Replace the P.C.B. if necessary.
Replace P.C.B.
Check correct circulation of the water and pump. Check
the correct position of the sensors.
Check the fan and the cable.
Check the sensor and the correct circulation of the water
and the pump.
Check the frequency (Hz) and the power supply.
Check the sensor.
Check the sensor.
Check the correct operation of the gas valve.
Check the power supply (V~).
Check the correct circulation of the water and the pump.
Check the correct circulation of the water and the pump.
Check the sensor.
Check the sensor.
437
438
566
500
501
502
528
1
2
557
505
1
2
E110
E110
E110
E117
E118
E125
E125
E125
E128
E129
E130
E133
E134
E135
E154
E160
E270
E317
E321
E321
E384
E385
E430
E430 & flame
E431
E431
Note: (s.c.) = Short Circuit
(o.c.) = Open Circuit