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

5
© 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

7
© 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.)

9
© 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