Viessmann VITOCROSSAL 300 Operating instructions

Service instructions
for contractors
VIESMANN
Vitocrossal 300
Type CT3U, 400 to 630 kW
Gas condensing boiler with MatriX cylinder burner
for natural gas E and LL
For applicability, see the last page
VITOCROSSAL 300
5783 337 GB 8/2017 Please keep safe.

2
Please follow these safety instructions closely to
prevent accidents and material losses.
Safety instructions explained
Danger
This symbol warns against the risk of injury.
!Please note
This symbol warns against the risk of material
losses and environmental pollution.
Note
Details identified by the word "Note" contain additional
information.
Target group
These instructions are exclusively intended for quali-
fied contractors.
■Work on gas installations may only be carried out by
a registered gas fitter.
■Work on electrical equipment may only be carried
out by a qualified electrician.
■The system must be commissioned by the system
installer or a qualified person authorised by the
installer.
Regulations to be observed
■National installation regulations
■Statutory regulations for the prevention of accidents
■Statutory regulations for environmental protection
■Codes of practice of the relevant trade associations
■All current safety regulations as defined by DIN, EN,
DVGW, TRGI, TRF, VDE and all locally applicable
standards
aÖNORM, EN, ÖVGW G K directives,
ÖVGW-TRF and ÖVE
cSEV, SUVA, SVGW, SVTI, SWKI, VKF and
EKAS guideline 1942: LPG, part 2
Safety instructions for working on the system
Working on the system
■Where gas is used as the fuel, close the main gas
shut-off valve and safeguard it against unintentional
reopening.
■Isolate the system from the power supply, e.g. by
removing the separate fuse or by means of a mains
isolator, and check that it is no longer live.
■Safeguard the system against reconnection.
■Wear suitable personal protective equipment when
carrying out any work.
Danger
Hot surfaces can cause burns.
■Before maintenance and service work, switch
OFF the appliance and let it cool down.
■Never touch hot surfaces on the boiler, burner,
flue system or pipework.
!Please note
Electronic assemblies can be damaged by elec-
trostatic discharge.
Prior to commencing work, touch earthed
objects such as heating or water pipes to dis-
charge static loads.
Repair work
!Please note
Repairing components that fulfil a safety func-
tion can compromise the safe operation of the
system.
Replace faulty components only with genuine
Viessmann spare parts.
Safety instructions
Safety instructions
5783 337 GB

3
Auxiliary components, spare and wearing parts
!Please note
Spare and wearing parts that have not been tes-
ted together with the system can compromise its
function. Installing non-authorised components
and making non-approved modifications or con-
versions can compromise safety and may inva-
lidate our warranty.
For replacements, use only original spare parts
supplied or approved by Viessmann.
Safety instructions for operating the system
If you smell gas
Danger
Escaping gas can lead to explosions which may
result in serious injury.
■Do not smoke. Prevent naked flames and
sparks. Never switch lights or electrical appli-
ances on or off.
■Close the gas shut-off valve.
■Open windows and doors.
■Evacuate any people from the danger zone.
■Notify your gas or electricity supply utility from
outside the building.
■Have the power supply to the building shut off
from a safe place (outside the building).
If you smell flue gas
Danger
Flue gas can lead to life threatening poisoning.
■Shut down the heating system.
■Ventilate the installation site.
■Close doors to living spaces to prevent flue
gases from spreading.
What to do if water escapes from the appliance
Danger
If water escapes from the appliance there is a
risk of electrocution.
Switch OFF the heating system at the external
isolator (e.g. fuse box, domestic distribution
board).
Danger
If water escapes from the appliance there is a
risk of scalding.
Never touch hot heating water.
Condensate
Danger
Contact with condensate can be harmful to
health.
Never let condensate touch your skin or eyes
and do not swallow it.
Flue systems and combustion air
Ensure that flue systems are clear and cannot be
sealed, for instance due to accumulation of conden-
sate or other external causes.
Avoid continuous condensate disposal with a wind pro-
tector.
Ensure an adequate supply of combustion air.
Inform system users that subsequent modifications to
the building characteristics are not permissible (e.g.
cable/pipework routing, cladding or partitions).
Danger
Leaking or blocked flue systems, or an inade-
quate supply of combustion air can cause life
threatening poisoning from carbon monoxide in
the flue gas.
Ensure the flue system is in good working order.
Vents for supplying combustion air must be non-
sealable.
Extractors
Operating appliances that exhaust air to the outside
(extractor hoods, extractors, air conditioning units, etc.)
can create negative pressure. If the boiler is operated
at the same time, this can lead to a reverse flow of flue
gas.
Danger
The simultaneous operation of the boiler and
appliances that exhausts air to the outside can
result in life threatening poisoning due to a
reverse flow of flue gas.
Fit an interlock circuit or take suitable steps to
ensure an adequate supply of combustion air.
Safety instructions
Safety instructions (cont.)
5783 337 GB

4
1. Information Symbols ................................................................................................. 5
Intended use .......................................................................................... 5
2. Commissioning, inspec-
tion, maintenance
Steps - commissioning, inspection and maintenance ............................ 6
3. Control unit Setting the codes at the control unit ...................................................... 25
4. Troubleshooting Diagnosis ............................................................................................... 32
■Faults displayed on the display and programming unit (fault codes) .. 32
■Faults without fault display ................................................................. 37
5. Burner control unit flow
chart
................................................................................................................ 38
6. Parts lists Overview of assemblies ......................................................................... 41
Boiler assembly ..................................................................................... 42
Thermal insulation assembly ................................................................. 44
Burner assembly .................................................................................... 46
Parts not shown ..................................................................................... 48
7. Component overview ................................................................................................................ 49
8. Connection and wiring dia-
gram
Burner control unit connection diagram ................................................. 50
■MatriX cylinder burner ........................................................................ 50
Mains filter unit connection diagram ...................................................... 51
9. Water quality requirements ................................................................................................................ 52
10. Reports Water quality .......................................................................................... 54
Settings and test values ......................................................................... 54
11. Specification ................................................................................................................ 56
12. Final decommissioning
and disposal
................................................................................................................ 57
13. Certificates EU Declaration of Conformity ................................................................ 58
Manufacturer's certificate ....................................................................... 59
14. Keyword index ................................................................................................................ 60
Index
Index
5783 337 GB

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Symbol Meaning
Reference to other document containing
further information
1.
Step in a diagram:
The numbers correspond to the order in
which the steps are carried out.
Warning of material losses and environ-
mental pollution
Live electrical area
Pay particular attention.
■Component must audibly click into place.
or
■Acoustic signal
■Fit new component.
or
■In conjunction with a tool: Clean the sur-
face.
Dispose of component correctly.
Dispose of component at a suitable collec-
tion point. Do not dispose of component in
domestic waste.
The steps in connection with commissioning, inspec-
tion and maintenance are found in the "Commission-
ing, inspection and maintenance" section and identified
as follows:
Symbol Meaning
Steps required during commissioning
Not required during commissioning
Steps required during inspection
Not required during inspection
Steps required during maintenance
Not required during maintenance
Intended use
The appliance is only intended to be installed and
operated in sealed unvented heating systems that
comply with EN 12828, with due attention paid to the
associated installation, service and operating instruc-
tions as well as the details in the datasheet.
It is only designed for the heating up of heating water.
Commercial or industrial usage for a purpose other
than the heating up of heating water shall be deemed
inappropriate.
Intended use presupposes that a fixed installation in
conjunction with permissible components designed for
this purpose has been carried out.
Every other use will be deemed to be inappropriate.
Any resulting losses are excluded from the manufac-
turer's liability.
Any usage beyond this must be approved by the man-
ufacturer for the individual case.
Intended use also includes the adherence to mainte-
nance and inspection intervals.
Information
Symbols
5783 337 GB
Information

6
Commissioning steps
Inspection steps
Maintenance steps Page
• • 1. Information on maintenance work.................................................................................... 8
•2. Checking the high limit safety cut-out setting................................................................ 8
•3. Filling the heating system with water and venting......................................................... 8
•4. Filling the trap with water.................................................................................................. 8
••• 5. Commissioning the system............................................................................................... 9
•6. Checking the gas type....................................................................................................... 10
•7. Converting to natural gas LL............................................................................................ 10
••• 8. Checking static pressure and supply pressure.............................................................. 11
••• 9. Checking the CO2 content................................................................................................. 12
••• 10. Checking the CO content
••• 11. Checking the flue gas temperature
• • 12. Checking the ionisation current....................................................................................... 14
• • 13. Shutting down the system................................................................................................. 14
• • 14. Opening the boiler door..................................................................................................... 15
• • 15. Separating the neutralising system from the boiler, connecting the drain hose......... 16
• • 16. Cleaning the combustion chamber and heating surfaces............................................. 17
• • 17. Checking the gaskets and thermal insulation sections................................................. 17
• • 18. Checking all connections on the heating water side for tightness............................... 17
• • 19. Cleaning and reconnecting the condensate drain system............................................. 17
• • 20. Checking the condensate drain and neutralising system (if installed)......................... 18
• • 21. Checking the burner gauze assembly.............................................................................. 18
• • 22. Checking the ignition and ionisation electrodes............................................................ 19
• • 23. Cleaning the burner........................................................................................................... 19
•24. Installing the burner........................................................................................................... 20
• • 25. Closing the boiler door...................................................................................................... 20
• • 26. Automatic tightness test on the two gas train valves.................................................... 20
• • 27. Checking the filter element in the gas line (if installed) and replacing if required
••• 28. Checking all gas connections for tightness.................................................................... 21
••• 29. Checking the rotary damper setting................................................................................. 21
•30. Performing final checks..................................................................................................... 22
• • 31. Checking the water quality................................................................................................ 22
••• 32. Checking the function of the safety valves
••• 33. Checking the temperature controller setting if a building management system is
used (DCC system)............................................................................................................ 22
• • 34. Checking the expansion vessel and system pressure................................................... 22
• • 35. Checking the flue gas collector for tightness................................................................. 23
• • 36. Checking the mixer for ease of operation and leaks...................................................... 23
••• 37. Checking the thermal insulation for firm seating
•38. Checking the flue system for leaks
Commissioning, inspection, maintenance
Steps - commissioning, inspection and maintenance
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Commissioning steps
Inspection steps
Maintenance steps Page
• • 39. Checking the ventilation air apertures in the installation room (only for open flue
operation)
•40. Instructing the system user.............................................................................................. 23
•41. Operating and service documents................................................................................... 24
Commissioning, inspection, maintenance
Steps - commissioning, inspection and… (cont.)
5783 337 GB

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The product contains ceramic fibres. Danger
When working with high temperature insulation
materials that contain zirconium or aluminium
silicate ceramic fibres, fibre dust may
develop. This fibre dust can be harmful to
health.
Only trained personnel may adapt or replace the
insulation. Wear suitable protective clothing,
especially breathing equipment and safety gog-
gles.
Checking the high limit safety cut-out setting
The high limit safety cut-out must not be set higher
than 110 °C. If required, set it to a maximum of 110 °C.
Control unit installation and service instructions
Filling the heating system with water and venting
Record the fill volume, water hardness and pH value in
the table on page 54. !Please note Unsuitable water quality can result in damage to
the boiler shell and the heating system.
Observe the "Water quality requirements" on
page 52 onwards.
Filling the trap with water
AB
Fig. 1
1. Remove lower back panel A by undoing the 4
quarter-turn rotary latches B.
2. Undo the siphon and fill with water, otherwise flue
gas may escape.
Commissioning, inspection, maintenance
Information on maintenance work
5783 337 GB

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3. Check that the condensate can drain freely. 4. Refit the siphon.
Commissioning the system
Control unit operating and service instructions,
and neutralising system operating instructions
01. Check the heating system pressure.
Permissible boiler operating pressure: 5.5 bar
(550 kPa)
02. For open flue operation: Check that the ventilation
facility in the installation room is open.
03. Check the gas supply pressure.
04. Open the gas line shut-off valves.
05. Switch ON the mains isolator (outside the installa-
tion room).
06.
A B
D
C
Fig. 2
Switch ON system ON/OFF switch B at the con-
trol unit. If fault indicator A on the control unit illu-
minates and display C on the burner control unit
flashes, first reset the system. For this, press reset
button D on the burner control unit.
Note
The system can enter a fault state during commis-
sioning due to a lack of gas in the gas line. The
fault indicator on the control unit then illuminates.
Purge the gas line again and reset the burner con-
trol unit.
07. Adjust the codes on the boiler control unit in
accordance with the table on page 25.
Control unit installation and service instruc-
tions
08. Check the function of the neutralising system and
the hydraulic seal in the trap.
Neutralising system operating instructions
09. Check all gaskets and plugs, and retighten if nec-
essary.
Note
We recommend checking all connections on the
heating water side for leaks approx. every 500
hours run. See page 17.
10. Check the boiler door and flue gas collector cover
a few days after commissioning and retighten all
screws.
Danger
For safe operation, a minimum operating pres-
sure of 0.5 bar (50 kPa) is absolutely essential.
A minimum pressure switch can be used to
safeguard this.
Commissioning, inspection, maintenance
Filling the trap with water (cont.)
5783 337 GB

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1. Check with your gas supply utility regarding the
gas type and Wobbe index (Wo).
■With the natural gas E setting, the boiler can be
operated in the Wobbe index range 12.0 to
16.1 kWh/m3 (43.2 to 58.0 MJ/m3).
■With the natural gas LL setting, boilers can be
operated in the Wobbe index range 10.0 to
13.1 kWh/m3 (36.0 to 47.2 MJ/m3) (not in a or
c).
2. In the delivered condition, the burner is preset for
natural gas E. If necessary, convert the burner to
the other gas type (see page 10) in accordance
with the details provided by the gas supply utility.
3. Record the gas type in the report (on page 54).
Converting to natural gas LL
(Not in a and c)
01. Close the gas shut-off valve.
02. Switch OFF the system ON/OFF switch on the
control unit.
03. Switch OFF the mains isolator (outside the instal-
lation room) or isolate the mains power and
secure against unintentional reconnection.
04. Pull connecting cables from the gas train.
05. Undo fitting A.
A
B
C
D
G
F
E
Fig. 3
06. Pull compensation hose G from the gas train.
07. Release the gas train from flange E.
08. Remove restrictor C with rubber cork gasket D.
09. Secure the gas train (without restrictor C and
without rubber cork gasket D, but with O-ring B)
at flange E. Replace the factory-fitted screws
M 5 × 16 with the supplied screws M 5 × 12.
10. Secure fitting A.
11. Fit compensation hose G onto the gas train.
12. Affix supplied label "Set to..." F over the existing
label.
13. Start the burner (see page 9).
Danger
Escaping gas leads to a risk of explosion.
Check the fitting for gas tightness.
!Please note
The use of leak detection spray can result in
faulty operation.
Leak detection spray must not come into contact
with electrical contacts.
Commissioning, inspection, maintenance
Checking the gas type
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Static pressure
A
Fig. 4
1. Close the gas shut-off valve.
2. Undo the screw in test connector A, but do not
remove.
3. Connect the pressure tester at test connector A.
4. Open the gas shut-off valve.
5. Check the static pressure (max. 60 mbar (6 kPa)).
6. Record the actual value in the report (on
page 54).
Supply pressure
1. Start the burner.
Note
For commissioning, see page 9. Switch the burner
to maximum heating output by activating the emis-
sions test switch at the control unit.
2. Check the supply pressure (flow pressure); see
table on page 11.
Note
The supply pressure (flow pressure) must be
between 18 and 50 mbar (1.8 and 5 kPa) (nominal
20 mbar (2 kPa)). The gas pressure switch mini-
mum (GDW 1) is factory-set to 10 mbar (1 kPa).
Never alter this setting.
3. Record the actual value in the report (on
page 54).
4. Close the gas shut-off valve.
5. Remove the pressure tester and close test connec-
tor A.
Supply pressure
(flow pressure)
Measure
< 15 mbar (1.5 kPa) Do not make any adjustments. Notify the gas supply utility.
15 to 18 mbar
(1.5 to 1.8 kPa)
Please note: The boiler may only be operated temporarily with this setting (emergen-
cy mode).
Notify the gas supply utility.
18 to 50 mbar
(1.8 to 5 kPa)
Start the boiler.
> 50 mbar (5 kPa) Install a separate gas pressure governor with zero off upstream of the boiler system,
and set the pressure to 20 mbar (2 kPa).
Notify the gas supply utility.
Commissioning, inspection, maintenance
Checking static pressure and supply pressure
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Preparing the test
C
D
E
F
Fig. 5
1. Open the gas shut-off valve.
2. Start the burner.
3. Press "S" E and "-" D simultaneously.
Display C then shows the following:
■Status: "d" (= control stop)
■Service: Modulation level in % ("00" = 100 % =
upper heating output, "0" = 0 % = lower heating
output)
CO2 test at the upper heating output
C
D
E
F
Fig. 6
1. Press "+" F until the service display has incre-
mented to "00" (= 100 %).
2. Note
The CO2 content for all natural gases must be
between 7.5 and 10.5 %.
Check the CO2 content at the flue pipe.
Rated heating
output in kW
Permissible CO2 content in
%
400 8.6 ± 0.3
500 8.6 ± 0.3
630 8.6 ± 0.3
AB
Fig. 7
3. If the CO2 content needs adjusting:
■Remove cap B.
■Turn setting screw A in small increments (3 mm
Allen key) until the CO2 content lies within the
specified range:
–Turning clockwise
→ CO2 content falls
–Turning anti-clockwise
→ CO2 content rises
4. Record the actual value in the report (on page
54).
!Please note
The CO2 content must always be lower in
partial load than it is in full load.
Commissioning, inspection, maintenance
Checking the CO2 content
5783 337 GB

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CO2 testing at the lower heating output
C
D
E
F
Fig. 8
1. Press "-" D until the service display has decre-
mented to "0" (lower heating output).
2. Note
The CO2 content for all natural gases must be
between 7.5 and 10.5 %.
Check the CO2 content at the flue pipe. The CO2
content must be 0.3 % lower in partial load than it
is in full load.
Rated heating
output in kW
Permissible CO2 content in
%
400 8.3 ± 0.3
500 8.3 ± 0.3
630 8.3 ± 0.3
B A
Fig. 9
3. If the CO2 content needs adjusting:
■Undo cover B.
■Turn adjusting screw A in small increments
(Torx 40) until the CO2 content lies within the
specified range:
–Turning clockwise
→ CO2 content rises
–Turning anti-clockwise
→ CO2 content falls
4. Record the actual value in the report (on
page 54).
!Please note
The CO2 content must always be lower in
partial load than it is in full load.
Rechecking the values
Regulate to the upper and lower heating output
again using the programming unit in the burner
control unit. If the values do not match the permis-
sible CO2 content according to the table on
page 12, repeat the steps for the upper and lower
heating output.
5. Press "S" E and "-" D simultaneously. The
burner continues at the original modulation level at
which status "d" (= control stop) was initiated. The
burner then returns to operating mode.
Checking the CO content
Commissioning, inspection, maintenance
Checking the CO2 content (cont.)
5783 337 GB

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Checking the ionisation current
A
CD
B
Fig. 10
01. Switch OFF the mains isolator.
02. Pull out ionisation cable plug C.
03. Switch ON the mains isolator.
An attempted burner start-up must be followed by
a fault shutdown. Fault code "F A7" flashes on dis-
play B.
04. Switch OFF the mains isolator.
Note
Test cable no. 1 is required when running the
check with the Testomatik-Gas. This test can also
be carried out with a multimeter.
05. Join ionisation cable plug C and adaptor D.
06. Push test cable socket A onto the ionisation elec-
trode.
07. Switch ON the mains isolator and press the reset
button.
08. Check the ionisation current.
Note
Approx. 2 to 3 s after the gas valve has opened
and during operation the ionisation current should
be at least 3 µA.
09. Record the actual value in the report (on
page 54).
10. Switch OFF the mains isolator, remove the test
equipment and reconnect the ionisation cable con-
nectors.
11. Switch ON the mains isolator.
Shutting down the system
1. Switch OFF the mains isolator or the power supply,
and safeguard against unauthorised reconnection.
Danger
Mains voltage can be life threatening.
For maintenance work, isolate the gas fan
from the power supply.
2. Pull connection plugs fÖ, fA, lÖ and fÖ/aBH from
the burner.
3. Close the gas shut-off valve.
Commissioning, inspection, maintenance
Checking the flue gas temperature
5783 337 GB

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Danger
When working with high temperature insulation
materials that contain zirconium or aluminium
silicate ceramic fibres, fibre dust may
develop. This fibre dust can be harmful to
health.
Only trained personnel may adapt or replace the
insulation. Wear suitable protective clothing,
especially breathing equipment and safety gog-
gles.
A
C
B
E
D
F
Fig. 11
1. Undo the quarter-turn rotary latches on the sides of
burner hood A and remove burner hood A.
2. Release burner cables C with plugs fA and lÖ at
the burner control unit and remove them from the
burner casing.
3. Release power cable D with plug fÖ and control
unit connecting cable F with plug fÖ/aBH at the
burner and the strain relief; remove them from the
burner casing.
4. Remove gas supply pipe B.
Commissioning, inspection, maintenance
Opening the boiler door
5783 337 GB

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E
6x
Fig. 12
5. Undo 6 screws on boiler door E and open it.
!Please note
Scratches inside the combustion chamber can
lead to corrosion.
Never place tools or other objects inside the
combustion chamber.
Separating the neutralising system from the boiler, connecting the drain
hose
A
BD
E
C
Fig. 13
1. Separate hose A to the neutralising system from
siphon B.
2. Undo siphon B from condensate drain C.
3. Connect drain hose D to condensate drain C and
route it to drainage system E.
Commissioning, inspection, maintenance
Opening the boiler door (cont.)
5783 337 GB

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4. Clean the combustion chamber and heating surfa-
ces.
5. Remove drain hose D and clean the inside of con-
densate drain C with a plastic brush.
6. Connect siphon B and hose A.
7. Fill trap B with water (see page 8).
Cleaning the combustion chamber and heating surfaces
Thoroughly clean the combustion chamber and heat-
ing surfaces with a water jet.
!Please note
Scratches on parts that come into contact with
flue gas can lead to corrosion.
Only use plastic brushes, no wire brushes or
sharp objects.
For normal cleaning, flush the heating surfaces thor-
oughly with a jet of water. For stubborn residues, sur-
face discolouration or soot deposits cleaning agents
may be used.
For this, observe the following:
■Only use solvent-free cleaning agents. Ensure that
no cleaning agent gets between the boiler body and
the thermal insulation.
■Remove soot deposits with an alkaline cleaning
agent with surfactant additive (e.g. Fauch 600).
■Remove coatings and surface discolouration (yellow-
brown) with slightly acidic, chloride-free cleaning
agents based on phosphoric acid (e.g. Antox 75 E).
■Remove loose deposits from the boiler; thoroughly
flush the heating surfaces and the flue gas collector
with a water jet.
Cleaning agent manufacturer's instructions
Note
"Fauch 600" and "Antox 75 E"
Manufacturer:
Hebro Chemie GmbH
Rostocker Strasse 40
D-41199 Mönchengladbach
Checking the gaskets and thermal insulation sections
1. Check the gaskets and packing cord in the boiler
door for damage.
2. Check the thermal insulation components on the
boiler door for damage.
3. Replace any damaged parts.
Checking all connections on the heating water side for tightness
Danger
There is a risk of injury when working on pres-
surised components.
The connections on the heating water side must
only be opened after the boiler has been dep-
ressurised.
Only drain the boiler with a suction pump when
the boiler air vent valve is open.
Note
Also check the connections for the control equipment
and the minimum pressure switch (low water indicator)
for tightness.
Cleaning and reconnecting the condensate drain system
Note
Clean the inside of the condensate drain system at
least annually.
Commissioning, inspection, maintenance
Separating the neutralising system from the… (cont.)
5783 337 GB

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AB
C
D
E
Fig. 14
1. Disconnect drain hose C.
2. Clean the inside of the condensate drain system
(hose, pipes).
3. Clean the neutralising system (if installed) in
accordance with the manufacturer's instructions.
Neutralising system operating instructions
Note
The neutralising agent can be ordered with part
no. 9521702.
4. Undo and flush lower part D of siphon E.
5. Fill lower part D of siphon E with water and refit.
6. Fasten the 4 quarter-turn rotary latches B and
remount lower back panel A.
Checking the condensate drain and neutralising system (if installed)
Fill water into the combustion chamber.
Note
The water must flow from the condensate drain pipe
without backing up.
If necessary, clean the condensate drain pipe again.
Checking the burner gauze assembly
Installation instructions for burner components
Commissioning, inspection, maintenance
Cleaning and reconnecting the condensate drain… (cont.)
5783 337 GB

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A
B
Fig. 15
1. Check the wire mesh and cover of burner gauze
assembly A for damage. Slight wavy deforma-
tions in burner gauze assembly A are not prob-
lematic.
2. Replace burner gauze assembly A if required.
3. Check seal B between the burner gauze assem-
bly and thermal insulation. If required, replace seal
B.
Checking the ignition and ionisation electrodes
Ignition electrodes
8.5 1
±
Fig. 16
71.5
+
61
±
Fig. 17
Ionisation electrode
15.5 1
±
Fig. 18
Check the ignition electrodes and ionisation electrode
for the correct gap to the burner gauze assembly and
for possible damage. Replace the electrodes if
required.
Cleaning the burner
B
C
E
D
A
F
Fig. 19
1. Undo fitting C on gas supply pipe B.
2. Undo Venturi mixing pipe D from fan E.
3. Remove Venturi mixing pipe D with gas train A
and gas supply pipe B. Disconnect the connecting
cables.
Commissioning, inspection, maintenance
Checking the burner gauze assembly (cont.)
5783 337 GB

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4. Disconnect the connecting cables from fan E.
Remove the fan.
Danger
Mains voltage can be life threatening.
For maintenance work, isolate the gas fan
from the power supply.
Note
Ensure that the gasket between the fan casing and
the burner flange is correctly positioned.
5. Clean the fan housing and impeller with com-
pressed air.
6. If required, vacuum the inside of burner gauze
assembly F.
Installing the burner
B
C
E
D
A
Fig. 20
1. Mount fan E.
Note
Ensure that the gasket between the fan casing and
the burner flange is correctly positioned.
2. Plug the connecting cables onto fan E.
3. Secure Venturi mixing pipe D with gas train A
and gas supply pipe B to fan E. Attach the con-
necting cables.
4. Tighten fitting C on gas supply pipe B.
Danger
Escaping gas leads to a risk of explosion.
Check the fitting and gasket between the fan
casing and the burner flange for gas tight-
ness.
Closing the boiler door
Note
Tighten the boiler door screws evenly and diagonally,
with a torque of at least 18 Nm.
Danger
Leaks can result in a risk of poisoning through
escaping gas.
Prior to commissioning, check the boiler door
gasket for correct seating and realign if neces-
sary. Otherwise secondary ventilation may
occur, with condensate forming on the boiler
door, and gas may escape.
Automatic tightness test on the two gas train valves
The burner control unit automatically checks the valves
for tightness when the burner is started. If the valves
are gas-tight, the burner enters standard mode and
starts up.
If the 1st valve is not tight, fault code "F AE" is shown
on the burner control unit display; if the 2nd valve is
not tight, fault code "F AF" is displayed.
In either case, the gas train must be replaced.
Danger
Escaping gas leads to a risk of explosion.
Check the test connectors for gas tightness.
Commissioning, inspection, maintenance
Cleaning the burner (cont.)
5783 337 GB