Italtherm CITY CLASS Series User manual

CITY CLASS
Manual
SERVICE
ENG
25 K - 30 K - 35 K
25 KR - 35 KR
Green Heating Technology

Green Heating Technology
2
SERVICE Manual City Class
Table of Content
Available models � � � � � � � � � � � � � � � � � � � � � � � � � � 2
PCB configuration � � � � � � � � � � � � � � � � � � � � � � � � � 3
Check list firs ignition � � � � � � � � � � � � � � � � � � � � � � � 3
Advided procedure on the field � � � � � � � � � � � � � � � 5
User guide � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 6
Access to the inside of the boiler � � � � � � � � � � � � � 7
Accessing the main board � � � � � � � � � � � � � � � � � � 7
Boiler internal components K � � � � � � � � � � � � � � � � 8
Boiler internal components KR � � � � � � � � � � � � � � � 9
Hydraulic components K � � � � � � � � � � � � � � � � � � 10
Hydraulic components KR � � � � � � � � � � � � � � � � � 11
Electrical diagram K � � � � � � � � � � � � � � � � � � � � � � 12
Electrical diagram KR � � � � � � � � � � � � � � � � � � � � � 13
Electrical connection between the boiler and
storage unit � � � � � � � � � � � � � � � � � � � � � � � � � � � 14
Heating system filling and pressuring � � � � � � � � � � 14
Draining the heating system K-KR � � � � � � � � � � � � 15
Hydraulic components
dismounting and mounting � � � � � � � � � � � � � � � � � � 16
DHW exchanger � � � � � � � � � � � � � � � � � � � � � � � � 17
Flowstat � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 17
3 way valve � � � � � � � � � � � � � � � � � � � � � � � � � � � � 17
Combustion components
dismounting and mounting � � � � � � � � � � � � � � � � � � 18
Main exchanger � � � � � � � � � � � � � � � � � � � � � � � � � 19
Gas valve � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 20
Siphon � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 21
Gas valve automatic calibration � � � � � � � � � � � � � 22
Gas valve manual calibration � � � � � � � � � � � � � � � 24
How to access the parameters � � � � � � � � � � � � � � 26
Parameters K-KR � � � � � � � � � � � � � � � � � � � � � � � � 27
Info menù � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 29
Error history � � � � � � � � � � � � � � � � � � � � � � � � � � � � 30
Errors K-KR � � � � � � � � � � � � � � � � � � � � � � � � � � � � 31
Service function � � � � � � � � � � � � � � � � � � � � � � � � � 32
Parameters - Values � � � � � � � � � � � � � � � � � � � � � � 33
Resistance values � � � � � � � � � � � � � � � � � � � � � � � � 33
Pump diagram K � � � � � � � � � � � � � � � � � � � � � � � � � � 34
Pump diagram KR� � � � � � � � � � � � � � � � � � � � � � � � � 35
Accessories
Remote control kit � � � � � � � � � � � � � � � � � � � � � � � 34
Outdoor sensor kit � � � � � � � � � � � � � � � � � � � � � � � 34
Two relais board � � � � � � � � � � � � � � � � � � � � � � � � � 35
Technical Data . . . . . . . . . . . . . . . . . . . . . . . .
ErP data � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � � 38
Technical boiler data K � � � � � � � � � � � � � � � � � � � � � 36
Technical boiler data KR � � � � � � � � � � � � � � � � � � � 41
Available models
Model GAS type* PCB configuration
code
City Class 25 K Max heat input 25 kW G20
(G31; G230)
30170
(31170)
City Class 25 KR Max heat input 25 kW G20
(G31; G230)
30180
(31180)
City Class 30 K Max heat input 30 kW G20
(G31; G230)
30270
(31270)
City Class 35 K Max heat input 33,2 kW G20
(G31; G230)
30370
(31370)
City Class 35 KR Max heat input 33,2 kW G20
(G31; G230)
30380
(31380)
* All the boilers are factory set to run on G20 and can be set to work with one of the other types of gas mentioned, using the technical
menu on the control panel and without component replacement.
K
KR
K
K
KR

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SERVICE Manual City Class
PCB Configuration Code
At every power on, display shows PCB configuration code, check if the matching with adhesive is correct as shown in the
picture here below.
Configuration Code is placed close to the control panel and it is visible leaving metal cover
PCB total reset
TOTAL RESET = PCB is forced to factory settings
It is advised for solving some puzzling problem on the field• Boiler Mode OFF
• Keep pressing for 15 sec buttons and and
• When display shows “-” sliding, release button and press RESET to confirm procedure.
• Display switches OFF and switches ON again showing “Co nF.E”
It means: “I need AESTHETIC CONFIGURATION !”
After this procedure, Boiler needs PCB Configuration
PCB Configuration
Once replaced PCB or after «Total RESET» procedure, Boiler has to be configured for model where it is mounted.
• Display shows “Co nF.E”
• Keep pressing buttons and : this way PCB recognize Boiler Aesthetic (1st digit)
• Set Parameter* 60 (Boiler Power), which is equal to 3rd digit of
Configuration Code, on left corner of Control Panel and store value pressing RESET.
• Set Parameter* 61 (Boiler Hydraulic), which is equal to 4th digit of
Configuration Code, on left corner of Control Panel and store value pressing RESET.
• Ending, PCB shows Configuration done.
On display and on the sticker there must be the same Configuration Code
* Acting on or for changing value
KKR
Digits 1st 2nd 3rd 4th 5th
Value Aestethic Gas Type Power Hydraulic Not used
30 170
G20
30 170
G20
31 170
G20
30 170

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SERVICE Manual City Class
Check list first ignition
Installation done under country regulation in force
Flues and Air system
60 mm silicon gasket correctly installed
No leakage between part of the system (extension, bends and flanges)
Avoiding flues recirculation, respecting the minimum distances between the flues
and air pipes with split configuration and between air/flues pipe and walls with the
concentric configuration
Hydraulic plant
Correct plant pressure with cold system temperature
Ensuring air bleeding
Checking tank connection (only KR).
If tank is not present, be sure to connect the flow and return together with a pipe for
ensuring the needed circulation,
Gas plant
Checking inlet pressure
Static……………………….mbar
Dynamic …………………….mbar
Avoiding gas leakage from the gas connection on the boiler
Electric connection
Checking correct electric supply (220-240V -15%...+10% 50Hz)
Checking the correct tank probe connection (only KR), after having removed the
factory-installed resistor
Condense syphon
Checking syphon cleanness (no obstructions on it)
Connecting to a waste water or treating its acidity with relevant products before
discharging on the environment.
Flue check
Checking CO2 value
CO2 Qr ………………..%
CO2 Qn ………………..%
If CO2 values are not correct, do the procedure “Manual Calibration”.
Gas conversion
NATURAL GAS G20 COMMERCIAL PROPANE G31
MOD. HEAT INPUT CO2at Qn
and ignition (%)
CO2at Qr
(%)
CO2at Qn
and ignition (%)
CO2at Qr
(%)
25 Nominal value 9.1 9.3 10.1 10.1
30 Allowed range 8.2...9.7 8.4...9.6 9.1...11.1 9.0...11.0
35
KKR
In the case of liquid gas fuel, it is important that the boiler be exclusively fuelled with
commercial Propane G31 and not with Butane G30. For this reason, we recommend that the
supplier of the fuel be informed, for example, by applying a suitable warning on the gas tank
or in its immediate vicinity, so that it is visible to the employee at the time it is being filled.

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SERVICE Manual City Class
Advised procedure on the field
AUTOMATIC CALIBRATION = Boiler Calibration Based On Tolerances Of Components
MANUAL CALIBRATION = System Calibration Based On Flues Configuration Features
CHECK COMBUSTION = Manual Operation By Technician With Flues Tester
COMPONENTS REPLACED
ADVISED PROCEDURE ON BOILER
#1 #2 #3
Main PCB AUTOMATIC CALIBRATION CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION
Gas Valve AUTOMATIC CALIBRATION CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION
Fan AUTOMATIC CALIBRATION CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION
Combustion Chamber AUTOMATIC CALIBRATION CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION
Burner CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION AUTOMATIC CALIBRATION
Detection/Ignition Electrode CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION AUTOMATIC CALIBRATION
Gas nozzle CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION AUTOMATIC CALIBRATION
Air-Gas Mixer CHECK COMBUSTION
(CO2values)
If necessary,
MANUAL CALIBRATION AUTOMATIC CALIBRATION
KKR
1. the boiler should be electrically powered and set in a mode different than . Use the button if necessary;
2. set the parameter 01 (see "ENTER PARAMETER" on the required gas kind the boiler is required to work with:
3. 0 = Natural gas (G20),
4. 1 = Propane (G31)
5. ensure that the inlet gas pressure complies with the required nominal pressure (see "Technical data" and that the gas
flow is sufficient to guarantee the appliance correct work with burner ON;
6. carry out the AUTOmatic combustion calibration - see paragraph "Combustion calibration"
7. carry out the combustion test - see paragraph "Combustion test" ;
8. apply the label indicating the type of gas (provided with the kit) in the area provided on the “WARNING” plate inside the
boiler; besides, write down the new configuration code of the main board (see table "Board configuration codes"

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SERVICE Manual City Class
User Guide
The front control panel: PUSHBUTTONS
Stand-by / Functioning mode
At every press, the boiler switches its mode from to
summer or winter mode.
00314 00
CH setting
To set the CH system temperature. If the Outdoor Sensor
Kit was installed, see also "Outdoor Sensor Kit" on page
46.
DHW setting
To set the DHW temperature.
RESET Press to reset the boiler in case of breakdown.
DISPLAY - symbols enabled in this model and their description
CH – winter mode indication
If flashing, it means that the boiler is functioning in CH mode. See also the remark in the descrition of symbol
.
Burner ON
It indicates the presence of the flame in the burner.
DHW mode indication
If flashing, it means that the boiler is functioning to produce hot water.
If both and symbols flash at the same time, a Technician-reserved function has been activated.
In this case, turn immediately the boiler off - and then turn it on again- by means of the button .
Two digit display under the symbol
Normally, it displays the CH flow temperature, i.e the temperature of the liquid on boiler's outlet that is sent to
the CH system.
During the CH temperature setting (by pressing the buttons and ), it shows the temperature value
changing; in case of alarm it displays "E"; during the setting (reserved to the Technician) it displays the
chosen parameter ID number
Three digit display under the symbol
Normally, it displays the temperature of the hot water on boiler’s outlet. When the boiler is in stand-by mode,
it displays .
During the DHW temperature setting (by pressing the buttons and ), it shows the temperature
value changing; in case of alarm it displays the ID number of the alarm;during the setting (reserved to the
Technician) it displays the value of the chosen parameter.
RESET It appears when the boiler is locked or anyway is present an error that the user could manage.
SERVICE It appears when the boiler has detected an error (mainly a fault) that has to be managed by the Technician.
It informs that the outdoor probe (accessories) is installed.
Note: In this case the CH system temperature is automatically set and so the use of buttons and
is different from the standard way: for deeper detailsrely on kit instruction and see “Outdoor
Sensor Kit”
KKR

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SERVICE Manual City Class
Access to the inside of the boiler
1. Unscrew the casing fixing screws1 and2;
2. pull the casing3 outwards, then push it upwards (to unhook it from the tongues6) and remove it;
3. unscrew the screws5 and6, then slide the control panel7 upwards and overturn it downwards. Then it’s possible to remove the
support 8 to better access the components;
4. after the regulations, close the boiler repeating everything in the other sense, carefully hooking the casing3 to the tongues4.
Accessing the main board
The main PCB has no hardware adjustment devices onboard, so no access to it is required, except in case of cabling check or replace-
ment of the board itself. Proceed as follows:
Cut off the electrical supply to the boiler. Restore the supply after
having closed the control panel rear cover.
funscrew the screws 1 and release the latches 2;
fremove the back cover of the control panel.
An incorrect or not complete closure of the electronic box voids the
IP grade of protection of the appliance. Ensure that all closing items
are correctly used and that all cables pass through the suitable
slots. If one or more latches 2 should break, please use holes 3
with suitable screws (similar to the standard ones 1).
KKR

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SERVICE Manual City Class
Boiler internal components K
1 Flue connection flange
2 Plug for Combustion analysis (air intake)
3 Plug for Combustion analysis (flue)
4 Expansion Vessel
5 Water drain pipe from air intake flange
6 Fan
7 Air/Gas Mixing device
8 Temperature Sensor on system return
9 Automatic Venting Device
(heating circuit, incorporated in the pump)
10 Safety valve 3 bar
11 Pump
12 Pipe for condense outlet
13 Drain valve
14 Priority flow switch (with filter)
15 Loss of water pressure switch
16 Gas valve
17 DHW temperature sensor
18 System pressure gauge
19 Filling valve
20 By-pass (in-built in the 3-way valve hydraulic
assembly)
21 DHW exchanger
22 Motorized 3-way valve
23 Siphon for condense outlet
24 Manual Venting Device (Combustion assembly)
25 Temperature Sensor, system flow
26 Safety thermostat on system flow
27 Air intake hose
28 Flame ignition/detection electrode
29 Combustion assembly (burner+primary
exchanger)
30 Flue overheat fuse
K
1618
1719 15
14
13
21
20
22
23
24
25
27
12
26
29
28
30
5
1
4
3
2
6
8
9
10
11
7
00365 00

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SERVICE Manual City Class
Boiler internal components KR
1 Flue connection flange
2 Plug for Combustion analysis (air intake)
3 Plug for Combustion analysis (flue)
4 Expansion Vessel
5 Water drain pipe from air intake flange
6 Fan
7 Air/Gas Mixing device
8 Temperature Sensor on system return
9 Loss of water pressure switch
10 Automatic Venting Device
(heating circuit, incorporated in the pump)
11 Safety valve 3 bar
12 Pump
13 Pipe for condense outlet
14 Drain valve
15 Gas valve
16 System pressure gauge
17 By-pass (in-built in the 3-way valve hydraulic
assembly)
18 Motorized 3-way valve
19 Siphon for condense outlet
20 Manual Venting Device (Combustion assembly)
21 Temperature Sensor, system flow
22 Safety thermostat on system flow
23 Air intake hose
24 Flame ignition/detection electrode
25 Combustion assembly (burner+primary exchanger)
26 Flue overheat fuse
KR
1516 14
17
18
19
20
21
23
13
22
25
24
26
5
1
4
3
2
6
8
9
10
11
12
7
00376 00

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SERVICE Manual City Class
Hydraulic components K
1 Flue connection flange
4 Expansion Vessel
5 Water drain pipe from air intake flange
6 Fan
7 Air/Gas Mixing device
8 Temperature Sensor on system return
9 Automatic Venting Device
(heating circuit, incorporated in the pump)
10 Safety valve 3 bar
11 Pump (including automatic venting device)
13 Drain valve
14 Priority flow switch (with filter)
15 Loss of water pressure switch
16 Gas valve
17 DHW temperature sensor
18 System pressure gauge
19 Filling valve
20 By-pass (in-built in the 3-way valve hydraulic
assembly)
21 DHW exchanger
22 Motorized 3-way valve
23 Siphon for condense outlet
24 Manual Venting Device (Combustion assembly)
25 Temperature Sensor, system flow
26 Safety thermostat on system flow
27 Air intake hose
51 Flue hood
52 Combustion chamber
53 Burner
54 Primary exchanger
55 Gas pipe
56 Inlet of water from air intake in the condense
siphon
57 Tap for condense siphon cleaning
58 Check valve
59 Condense drain in combustion assembly
R Heating return
M Heating flow
C Hot water outlet
F Cold water inlet
SCCondense drain
G Gas inlet
00327 01
M
RM CF GSC
6
7
55
54
53
52
51
4
59
18
20
19
15
10
13
11
9
25
8
5
24
26
27
1
21
14
16
23
17
56
57
22
58
K

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SERVICE Manual City Class
Hydraulic components KR
1 Flue connection flange
4 Expansion Vessel
5 Water drain pipe from air intake flange
6 Fan
7 Air/Gas Mixing device
8 Temperature Sensor on system return
9 Loss of water pressure switch
10 Automatic Venting Device
(heating circuit, incorporated in the pump)
11 Safety valve 3 bar
12 Pump (including automatic venting device)
14 Drain valve
15 Gas valve
16 System pressure gauge
17 By-pass (in-built in the 3-way valve hydraulic
assembly)
18 Motorized 3-way valve
19 Siphon for condense outlet
20 Manual Venting Device (Combustion assembly)
21 Temperature Sensor, system flow
22 Safety thermostat on system flow
23 Air intake hose
71 Flue hood
72 Combustion chamber
73 Burner
74 Primary exchanger
75 Gas pipe
76 Inlet of water from air intake in the condense
siphon
77 Tap for condense siphon cleaning
78 Condense drain in combustion assembly
R Heating return
M Heating flow
RBReturn from storage coil
MB Flow to storage coil
SCCondense drain
G Gas inlet
00375 00
M
RMRB MB GSC
6
7
75
74
73
72
71
4
78
16
17
9
11
14
12
10
21
8
5
20
22
23
1
15
19
76
77
18
KR

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SERVICE Manual City Class
Electrical diagram K
6.1 Fan - supply
6.2 Fan - speed control
8 Temperature Sensor on system return
11.1 Pump - supply
11.2 Pump - modulation control
14 Priority flow switch (with filter) (*)
15 Loss of water pressure switch (*)
16 Gas valve
17 DHW temperature sensor
22 Motorized 3-way valve
25 Temperature Sensor, system flow
26 Safety thermostat on system flow (*)
28 Ignition and flame detection Electrode
30 Flue overheat fuse
41 Fuse F2A (2A fast)
(*) the contacts of these components are shown
in rest conditions (cold condition, no system
pressure, no flow)
Optional external devices:
TA Room thermostat: (or Chronothermostat) SELV
simple contact. Closed contact = heating request.
or Remote control (original accessory only)
SE To optional outdoor temperature sensor
TA2 To optional room thermostat for zones with
different temperature range
AUX Input for optional device, configurable with
Parameter 46
Abbreviations: COMCommon ●NCNormally
closed (contact) ●NONormally open (contact)
●HEAHeating (diverting command) ●DHWHot
water (diverting command)
Colours: BKBlack ●BNBrown ●BUBlue
●GNGreen ●RDRed ●OGOrange ●VTViolet
●WHWhite ●YEYellow ●YGYellow-Green
K
12 6543..
PE NL
...
NC NO
YG
BN
BK
BU
RD
BK
RD
3 DHW 2 COM 1 HEA
WH WH
BN VT
BU BN
BK BK
RD
BK
VT
VT VT
GN GN
WH WH
OG OG
BU
RD
YG
BU
BN BN
BK BK
RD
BK
BU
BN
41
8
17
26
15 14
30 25
622 16
X2
6.26.1
X3 X4 X11 X13
X12
X10
X19
X7 X8
00364 INT 00
LN
AUX SE TA2
TA
28
11

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SERVICE Manual City Class
Electrical diagram KR
6.1 Fan - supply
6.2 Fan - speed control
8 Temperature Sensor on system return
9 Loss of water pressure switch (*)
12.1 Pump - supply
12.2 Pump - modulation control
15 Gas valve
18 Motorized 3-way valve
21 Temperature Sensor, system flow
22 Safety thermostat on system flow (*)
24 Ignition and flame detection Electrode
26 Flue overheat fuse
61 Fuse F2A (2A fast)
62 Resistor, 2.2 kOhm - 1/2W (**)
(*) the contacts of these components are shown in
rest conditions (cold condition, no system pressure,
no flow)
(**)see “Electrical connection between the boiler and
the storage unit”
Optional external devices:
63 DHW Storage temperature sensor (**)
64 DHW Storage thermostat (*) (**)
TA Room thermostat: (or Chronothermostat) SELV
simple contact. Closed contact = heating request.
or Remote control (original accessory only)
SE To optional outdoor temperature sensor
TA2 To optional room thermostat for zones with
different temperature range
AUX Input for optional device (also for DHW Storage
thermostat 64) configurable with Parameter 46
Abbreviations: COMCommon ●NCNormally
closed (contact) ●NONormally open (contact)
●HEAHeating (diverting command) ●DHWHot
water (diverting command)
Colours: BKBlack ●BNBrown ●BUBlue ●GNGreen
●RDRed ●OGOrange ●VTViolet ●WHWhite
●YEYellow ●YGYellow-Green
KR
12 6543
..
PE NL
...
NC NO
YG
BN
BK
BU
RD
BK
RD
3 DHW 2 COM 1 HEA
WH WH
BN VT
BU BN
BK BK
RD
BK
VT
VT VT
GN GN
WH WH
OG OG
RD
YG
BN BN
BK BK
RD
BK
BU
BN
61
8
STB
TB
62
22
9
26 21
618 15
X2
6.26.1
X3 X4
X11 X13
X12
X10
X19
X7 X8
00377 INT 01
LN
24
AUX SE TA2
TA
12

Green Heating Technology
14
SERVICE Manual City Class
Electrical connection between the boiler and the storage unit
Don’t connect the storage temperature sensor terminals to the power supply or to live wires.
As shown in “Electrical diagram” the boiler has two different inputs for the electrical connections to the storage unit:
STB: input for a storage temperature sensor: the boiler reads the storage temperature and, if necessary, switches to storage
heating mode to keep its temperature around the value set by means of the buttons and . Even if the storage
unit is NOT supplied by Italtherm, it’s necessary to use the original temperature sensor kit (NTC R=10kOhm at 25°C,
ß=3435). Only if the STB input is used, it’s necessary to remove the factory-installed resistor, that otherwise must be left
installed.
The cabling between the storage temperature sensor STB and the boiler must pass in a sheath separate from the ones
containing supply cables.
In every case, the maximum length for a 2 x 0.5mm² cable is 30m.
AUX: auxiliary input for storage thermostat (TB) or solar DHW heating request: when the contact is closed, the boiler work
is forced in DHW storage heating, until it opens (or up to the reaching of the max boiler temperature). To be used if the
storage has a thermostatic temperature control (even manually adjustable) or in connection with a solar system, to allow
it to require the heating of the storage when the solar heat contribution is insufficient.
Remark: to configure the AUX input for the storage thermostat, the Parameter 46 has to be set to value 1
Remark: if both inputs are used, functionally the TB has the priority on the STB, i.e. if TB is closed, the storage gets heated
even if the temperature measured by STB is higher than the set one.
Heating system filling and pressuring
Once all system connections have been carried out, proceed with system filling. This operation should be made with
care, respecting the following steps:
Open the radiators venting devices;
Check that the plug of the automatic air vent, incor-
porated in the boiler circulator, is unscrewed: if not,
unscrew it and leave it unscrewed, even afterwards,
for normal operation;
If it’s required to fill the system with anti-freeze solution,
do this operation, then hermetically close the con-
nection or the valve used to put the solution in, to
allow the pressurization.
Gradually open the filling cock 2 ;
Check the correct functioning of automatic venting de-
vices, eventually installed;
Close the radiators venting devices as soon as water
flows out of them;
Make sure, by reading the pressure gauge 1, that the
pressure reaches the optimal value of 1.0 bar (max
1.5 bar);
Close the water filling cock 2 and bleed each radiator
again;
Repeat the venting and pressurization operations until
the air is completely purged from the system.
KKR
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KR

Green Heating Technology
15
SERVICE Manual City Class
Draining the heating system
K
When it is necessary to drain the heating system, proceed as described
here below:
Connect a rubber pipe to the draining tap terminal 1 ;
put the other end of the pipe in a suitable drain or sink;
open the draining tap by turning the nut 2 counterclockwise, using a
suitable spanner;
when the pressure is COMPLETELY drained, it’s possible to open the
radiators venting valves, to allow the air inlet. The complete system drain
is possible only draining the liquid from the lowest point of the system
itself.
Remark: The complete system draining can be achieved only by draining
the system from its lowest point.
when everything is over, close taps (turning the nut 2 clockwise) and air
vents.
In the primary exchanger a certain quantity of water of the heating system
remains. If you want to remove the boiler from the wall, we advice you to
close with plugs the hydraulic inlet/outlet heating system connections.
KR
When it is necessary to drain the heating system, proceed as described
here below:
• Connect a rubber pipe to the draining tap terminal 1 ;
• put the other end of the pipe in a suitable drain or sink;
• open the draining tap by turning the nut 2 counterclockwise, using a
suitable spanner;
• when the pressure is COMPLETELY drained, it’s possible to open the
radiators venting valves, to allow the air inlet. The complete system
drain is possible only draining the liquid from the lowest point of the
system itself.
Remark: The complete system draining can be achieved only by draining
the system from its lowest point.
• when everything is over, close taps (turning the nut 2 clockwise) and air vents.
In the primary exchanger a certain quantity of water of the heating
system remains. If you want to remove the boiler from the wall,
we advice you to close with plugs the hydraulic inlet/outlet heating
system connections.
• Drain the storage unit if necessary (storage tank and/or primary coil). Refer to the
relevant documentation.
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KKR

Green Heating Technology
16
SERVICE Manual City Class
Hydraulic components KKR

Green Heating Technology
17
SERVICE Manual City Class
Dismounting & mounting
DHW EXCAHNGER TOOLS
tools suggested: allen key 4 mm - antiscale liquid for cleaning
DISMOUNTING
• discharge boiler water from both side (DHW and CH) see procedure
• rotate safety 3 bar (D) 90* clockwise to show the right fixing screw by hands
• unscrew 2 fixing screws (F) allen key 4 mm
• take out the DHW exchanger (H) by hand
• clean chemically or to replace it by hand
HOW TO CLEAN
• chemical cleaning with antiscale liquid on both sides of DHW exchanger
• rinse thoroughly with water
MOUNTING
• check effectiveness of 4 O-rings (G) by hands
• place DHW exchanger on its spot by hands
• screw 2 fixing screw (F) allen key 4 mm
• rotate safety 3 bar (D) 90° anticlockwise and connect its discharging pipe if it is the case by hands
• fill-in boiler water see procedure
FLOW STAT
tools suggested: allen key 4 mm - cross screwdriver
DISMOUNTING
• place flow stat to its spot on brass group by hands
• screw 2 fixing screws (A) to hydraulic metal bracket cross screwdriver
• screw 1 fixing screw (B) to brass group cross screwdriver
• rotate safety 3 bar (D) 90° anticlockwise and connect its discharging pipe if it is the case by hands
• plug flow stat electrically (C) by hands
• fill-in boiler with water see procedure
MOUNTING
• discharge water from DHW side see procedure
• unplug flow stat electrically (C) by hands
• rotate safety 3 bar (D) 90* clockwise to show the flow stat behind by hands
• unscrew 2 fixing screws (A) from hydraulic metal bracket cross screwdriver
• unscrew 1 fixing screw (B) from brass group cross screwdriver
• unscrew 1 screw (E) and to screw it where screw (B) has been left; this way flow stat will
leave easily its spot from brass group allen key 4 mm
• screw 1 screw (E) on the previous spot for future servicing allen key 4 mm
3 WAY VALVE
tools suggested: wrench 14 mm or 3/8” - wrench 30 mm or ¾”- allen key 4 mm - cross screwdriver -socket wrench 34 mm
DISMOUNTING
• discharge boiler water from both side (DHW and CH) see procedure
• dismount pipe (Q), dismount manometer (R) wrench 30 mm+wrench 14 mm
• dismount DHW exchanger (H) (see procedure) allen key 4 mm
• unscrew 2 fixing screws (L) and take out the brass group (I) cross screwdriver
• unscrew plastic nut (O) and take out first half of 3 way valve wrench 30 mm
• unscrew brass nut (P) and take out second half of 3 way valve socket wrench 34 mm
• remove 3 way valve clip (M) and leave the engine (N) by hands
• clean or to replace 3 way valve by hands
MOUNTING
• mount 2 half of 3 way valve, tightening plastic nut (O) and brass nut (P) wrench 30 mm - socket wrench
34 mm
• place brass group on the bracket and fix it with 2 screws (L) but not tighten them completely by hands
• mount DHW exchanger (H) (see procedure) allen key 4 mm
• mount pipe (Q) wrench 30 mm
• fix completely 2 screws (L) cross screwdriver
• mount manometer (R) wrench 14 mm
• fill-in boiler with water see procedure
KKR

Green Heating Technology
18
SERVICE Manual City Class
Combustion components KKR

Green Heating Technology
19
SERVICE Manual City Class
Dismounting & mounting
MAIN EXCAHNGER TOOLS
tools suggested: wrench 30 mm or ¾” - cross screwdriver - socket wrench 8 mm
DISMOUNTING
• leave electric supply and close the gas inlet by hands
• take out fixing clip on gas pipe (A) by hands
• unscrew gas pipe (B) wrench 30 mm
• loosen metal tie and take out the inlet air pipe from the fan (C) cross screwdriver
• remove electrode wire (D) by hands
• remove 2 electrical connectors from the fan by hands
• remove 4 nut 10 mm (E) socket wrench 10 mm
• take out door and fan together by hands
• remove 4 screws and take out the fan (F) socket wrench 8 mm
• remove 4 screws and take out the mixer (G) cross screwdriver
HOW TO CLEAN
• check electrode position on ther burner (4/5 mm)
• replace gaskets using the kit
• check integrity of insulation parts
• clean coil (on flues side) with a plastic brush and water (don’t use any aggressive liquid).
Coil material: stainless steel AISI 441
• check fan and eventually replace the gasket
• check and clean possible dirty on the mixer, coming from air inlet.
MOUNTING
• mount mixer on fan with 4 screws (G) cross screwdriver
• mount fan on the combustion door with 4 screws (F) socket wrench 8 mm
• connect 2 fan electrical connectors by hands
• mount door and fan together to the combustion group, fixing with 4 nuts 10 mm (E) socket wrench 10 mm
• mount plastic pipe on the mixer and fix it with metal tie (C) cross screwdriver
• mount electrode connector (D) by hands
• mount gas pipe and fix it with clip and brass nut (B) by hand / wrench 30 mm
• open gas inlet and switch on boiler electrically; check eventual gas leakage while a demand
is running relevant tools
KKR

Green Heating Technology
20
SERVICE Manual City Class
Gas valve
GAS VALVE TOOLS
tools suggested: wrench 30 mm or ¾” - cross screwdriver - flues tester
DISMOUNTING
• leave electric supply and close the gas inlet by hand
• take out electrical connector by hand
• to take out fixing clip on gas pipe by hand
• unscrew gas pipe wrench 30 mm
• remove 2 fixing screws from hydraulic bracket cross screwdriver
• replace gas valve by hand
• screw 2 fixing screws to the hydraulic bracket cross screwdriver
• mount gas pipe and fix it on the top with clip by hand
• tighten brass group wrench 30 mm
• mount electrical connector by hand
• open gas inlet and switch on boiler electrically; check eventual gas leakage while a demand
is running relevant tools
• make Automatic calibration see procedure
• make combustion analysis flues tester
Nozzle*
Coil 1 ON/OFF + Coli 2 ON/OFF and modulating
(Low Voltage supply)

*green side on the bottom (to gas valve)
ø 6 25 - 35 kW
ø 5,6 30 kW
No link to type of gas but only to Boiler Power.
KKR