Biasi GARDA HE M96.24SM/B2 User manual

Wall hung, fan flue, room sealed, high efficiency gas boiler
Service manual
GARDA HE
Models: G.C. Appl. No.
M96.24SM/B2 47---583---03A
M96.28SM/B2 47---583---04A
GARDA HE SILVER
Models: G.C. Appl. No.
M96.24SM/D2 47---583---03B
M96.28SM/D2 47---583---04B
Leave this manual adjacent to the gas meter

Ta b le o f c o n t e n t s
1 Overall information 1..................
1.1 Overall View 1.........................
1.2 Hydraulic diagram 1....................
2 General access and emptying
hydraulic circuits 2....................
2.1 Nomenclature 2........................
2.2 Body panels 2.........................
2.3 Control panel 2........................
2.4 Access to the sealed chamber 3.........
2.5 Emptying the primary circuit 3...........
2.6 Emptying the d.h.w. circuit 3............
3Diagrams 4...........................
3.1 Wiring diagram 4.......................
3.2 Functional flow diagrams 5..............
3.3 Circuit voltages 6......................
4Faultfinding 7........................
5 Primary heat exchanger 9..............
5.1 Function 9.............................
5.2 Removal 9............................
5.3 Cleaning 9............................
6 Condensing heat exchanger 10..........
6.1 Function 10.............................
6.2 Removal 10............................
7 D.h.w. heat exchanger 11...............
7.1 Function 11.............................
7.2 Removal 11............................
8Pump 12...............................
8.1 Function 12.............................
8.2 Checks 12.............................
8.3 Removal 12............................
9 Three way diverter valve 13.............
9.1 Function 13.............................
9.2 Checks 13.............................
9.3 Removal of the electric actuator 13........
9.4 Removal of the diverter group
and its internal parts 14..................
10 Electronic control/ignition p.c.b. 15......
10.1 Function 15.............................
10.2 Selection and adjustment devices 15......
10.3 Checking the temperature 16.............
10.4 Operation lights 17......................
10.5 Setting the boiler control function modes 17
10.6 Reignition frequency setting 18...........
10.7 Ignition gas pressure adjustment 18.......
10.8 Checks 19.............................
10.9 Removal of the electronic control p.c.b 19..
10.10 Thermal control in the ” ”mode 21......
10.11 Thermal control in the ” ”mode 21......
10.12 Ignition and control sequence 22..........
11 Modulating gas valve 23................
11.1 Function 23.............................
11.2 Nomenclature of the parts 23.............
11.3 Adjustment 23..........................
11.4 Checks 24.............................
11.5 Removal of the gas valve 24..............
12 Primary circuit flow switch 25...........
12.1 Function 25.............................
12.2 Checks 25.............................
12.3 Removal 25............................
13 Expansion vessel and
temperature -- pressure gauge 26........
13.1 Function 26.............................
13.2 Checks 26.............................
13.3 Removal of the expansion vessel 26.......
13.4 Removal of the temperature---pressure gauge
26
14 D.h.w. flow switch, filter and flow limiter 27
14.1 Function 27.............................
14.2 Nomenclature and location of parts 27.....
14.3 Checks 27.............................
14.4 Removal of the flow switch sensor 27......
14.5 Removal of the flow switch group
and d.h.w. circuit filter 28.................
14.6 Flow limiter 28..........................
15 Temperature probe 29..................
15.1 Function 29.............................
15.2 Checks 29.............................
15.3 Removal 29............................
16 By--pass valve 30......................
16.1 Function 30.............................
16.2 Removal 30............................
17 Fan, venturi device and
Air pressure switch 31..................
17.1 Function 31.............................
17.2 Checks 31.............................
17.3 Removal of the Fan 32...................
17.4 Inspection and removal of venturi device 32
17.5 Removal of the Air pressure switch 33.....
18 Ignition and detection electrodes 34.....
18.1 Function 34.............................
18.2 Checks 34.............................
18.3 Removal 34............................
19 Safety thermostat 35...................
19.1 Function 35.............................
19.2 Checks 35.............................
19.3 Removal 35............................
20 Flue temperature probe NTC 36.........
20.1 Function 36.............................
20.2 Checks 36.............................
20.3 Removal 36............................
21 Condensate trap 37....................
21.1 Function 37
.............................
21.2 Removal 37............................
22 Short spare parts list 38................

1
1Overall information
1.1 Overall View
Fan
Safety
thermostat
Main heat
exchanger
Burner
Ignition
electrodes
Gas valve
Control
panel
Combustion
chamber
Automatic
air release
Pump
D.h.w. temp.
probe
D.h.w.
heat exchanger
Expansion
vessel
Detection
electrode
valve
Condensing
Diverter valve
Air pressure
switch
Main circuit
Flue thermostat
heat exchanger
Condensate
trap
flow switch
C.h. temp.
probe
1.2 Hydraulic diagram
Central heating (c.h.) operation Domestic hot water (d.h.w.) operation
C.h.
water flow
C.h.
water return
D.h.w.
inlet
D.h.w.
outlet

2
2General access and emptying
hydraulic circuits
2.1 Nomenclature
2
6
1
54
3
Fig. 1
1 Right side panel
2 Front panel
3 Control panel lid
4 Control panel cover
5Servicepanel
6 Left side panel
2.2 Body panels
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
For the most part of the check and maintenance oper-
ations it is necessary to remove one or more panels of
the case.
Thesidepanelscanberemovedonlyaftertheremoval
of the front panel.
To remove the front panel remove screws A(Fig. 2), lift
the panel and remove it.
A
Fig. 2
To remove the side panels loosen the screws Band C
(Fig. 3), bring the base of the panels away from the
boiler and lift them, freeing them from the top hooks.
B
D
C
Fig. 3 --- bottom view of the boiler
2.3 Control panel
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
To gain access to the parts located inside the control
panel proceed as follows:
1 Remove the front panel of the case
2 Loosen the screws Band C(Fig. 3).
3RemovethescrewsD
4 Move the lower part of the side panels as indi-
cated in Fig. 4 and pull the control panel.
When completely pulled out, the panel can rotate
45˚downwards to facilitate the service oper-
ations on the internal parts.

General access and emptying hydraulic circuits
3
Fig. 4
5RemovethescrewsEand remove the service
panel (Fig. 5);
6 To gain access to the electronic regulation PCB
remove the screws Fand remove the control pan-
el lid (Fig. 5);
E
F
F
Fig. 5
2.4 Access to the sealed chamber
G
G
Fig. 6
To gain access to the parts contained in the sealed
chamber it is necessary to remove the lid of the sealed
chamber.
For this purpose, remove the front and side panels of
the case, remove the screws Gas indicated in Fig. 6
and remove the lid.
2.5 Emptying the primary circuit
1 Close the c.h. circuit flow and return cocks H.
(Fig. 7).
H
H
J
Fig. 7 --- bottom view of the boiler
2 Remove the front and right panels of the boiler.
3 Open the drain tap I(Fig. 8) until the boiler is com-
pletely emptied.
4 Close drain tap again once the emptying has
been completed.
I
Fig. 8
2.6 Emptying the d.h.w. circuit
5 Close the d.c.w. inlet cock J(Fig. 7);
6 Open one or more hot water taps until the boiler
has been completely emptied.

4
3Diagrams
3.1 Wiring diagram
LD1LD2LD3
F1
F2
K1 K3 K4
LD4
P4
X6
X1
X7
P5
SB1
X5
K2
X3
X2
X4
123
LN M
~3
2
1
X11
M
~
t t
t
Time switch
rd
wh
gn
Ignition
electrodes Flame detection
electrode
Condensate
trap
External controls
terminal block
Electric supply
terminal block
Three way
diverter valve
Pump Fan
M
~
Primary circuit
flow switch
Air pressure
switch
D.h.w. flow
switch
C.h. temperature
probe NTC Modulating
gas valve
Safety
thermostat
Flue
temperature
D.h.w. temperature
probe NTC
14
bn = brown
bu = blue
bk = black
wh = white
rd = red
gy = grey
gn = green
ye = yellow
vt = violet
og = orange
gnye = green/yellow
Remote control
terminal block
probe NTC
bu
bn
gnye
bu bn bk
bn bu
bn bu bk
bu bn
gnye
bn bu bk bu bn bk bu bn
bu bn
gnyebu
bn
gnye
bk
bk
gy
gy
gy
gy
bn bu
bk
wh
wh
wh
gy
bk
rd
rdwh
wh
bk
bk
bk
bk
bu
bn
gy*
gy
bu bu
rd
bu
wh
gy
wh
X8
gy*
rd
rd
gy
wh
bu
rd
bu
bu bk
* alternative, yellow
bn bubu

Diagrams
5
3.2 Functional flow diagrams
PTCJ 1 --- 1
L
General layout
Tra nsf orme r
N
Electronic
control p.c.b.
(low voltage section)
J 1 --- 2
J 3 --- 3
J 3 --- 5
J 3 --- 4
J 3 --- 2J 3 --- 1
J 2 --- 4J 2 --- 5
Three way
diverter valve
Pump
Full sequence
ignition device
Fuse 3,15 A
PTCJ 1 --- 1
L
Tra nsf orme r
ACTIVE CIRCUIT
INACTIVE CIRCUIT
L --- L IN E N --- N E U T R A L
N
Electronic
control p.c.b.
(low voltage section)
J 1 --- 2
J 3 --- 3
J 3 --- 5
J 3 --- 4
J 3 --- 2J 3 --- 1
J 2 --- 4J 2 --- 5
Three way
diverter valve
Pump
Full sequence
ignition device
Fuse 3,15 A
Heat request on d.h.w.
PTCJ 1 --- 1
L
Tra nsf o rme r
N
Electronic
control p.c.b.
(low voltage section)
J 1 --- 2
J 3 --- 3
J 3 --- 5
J 3 --- 4
J 3 --- 2J 3 --- 1
J 2 --- 4J 2 --- 5
Three way
diverter valve
Pump
Full sequence
ignition device
Fuse 3,15 A
Heat request on c.h.

Diagrams
6
3.3 Circuit voltages
LD1LD2LD3
F1
F2
K1 K3 K4
LD4
P4
X6
X1
X7
P5
SB1
X5
K2
X3
X2
X4
Electrical voltages with burner on
during c.h. or d.h.w. operation
only during c.h. operation
only during d.h.w. operation
Supply network
230~
230~
0
230~
230~
0
Pump
3way
230~
Modulating
Gas valve
diverter valve
Safety
thermostat
0
Fan
230~
0
Air
pressure
switch

7
4Fault finding
Components to check
Section of the manual ! (note ref. in brackets)
---
(1)
---
(2)
---
(3)
21.1 ---
(4)
78.2 9.2 10.8 11.4 12.2 14.5 15.2 16 17.2 18.2 19.2 20.1 ---
(7)
---
(8)
--- ---
L o c k --- o u t s i g n a l l a m p r e d
Defect #
Power supply line
Gas supply line
Flue pipes
Condensate drain pipe and trap
C.h. circuit
D.h.w. circuit
D.h.w. heat exchanger
Pump
Diverter valve
D.h.w. flow switch
Fuses (Electronic p.c.b.)
Electronic p.c.b.
Boiler settings
Gas valve (on---off operators)
Gas valve (modulating operator)
Main circuit flow switch
D.h.w. filter
Main circuit temp. probe
D.h.w. temp. probe
B y --- p a s s v a l v e
Fan and venturi device
Air pressure switch
Ignition electrode
Detection electrode
Safety thermostat
Flue thermostat
Injectors
Expansion vessel
Safety valve
Pressure gauge
By pressing the reset push--- button the boiler turns on and operates cor- rectly.
J J
(6)
J J J
By pressing the reset push--- button the boiler starts the ignition cycle. The burner doesn’t light on, the igni-
tion sparks continue and the boiler locks again.
J J J J J
ON
By pressing the reset push--- button the boiler starts the ignition cycle. The burner lights on, the ignition sparks continue and the boiler locks again.
J J J J J J
The boiler does not start either in c/h or d.h.w. mode. All the operation lights OFF Fan still.
J J J
The burner doesn’t light either in c.h. or d.h.w. mode. Fan turns.
J J J J
The burner doesn’t light either in c.h. or d.h.w. mode. Fan doesn’t turn.
J J J J J J J J
The boiler doesn’t control the d.h.w. temperature. Turning the d.h.w. temp. adjustment knob hasn’t effect on the modulation of the flame. The boiler operates correctly on c.h.
J J
OFF
The boiler lights for a short while on c.h. Normal operation on d.h.w. function.
J J

8
Components to check
Section of the manual ! (note ref. in brackets)
---------
(8)
---
(7)
20.119.218.217.21615.214.512.211.410.89.28.27---
(4)
21.1---
(3)
---
(2)
---
(1)
L o c k --- o u t s i g n a l l a m p r e d
Pressure gauge
Safety valve
Expansion vessel
Injectors
Flue thermostat
Safety thermostat
Detection electrode
Ignition electrode
Air pressure switch
Fan and venturi device
B y --- p a s s v a l v e
D.h.w. temp. probe
Main circuit temp. probe
D.h.w. filter
Main circuit flow switch
Gas valve (modulating operator)
Gas valve (on---off operators)
Boiler settings
Electronic p.c.b.
Fuses (Electronic p.c.b.)
D.h.w. flow switch
Diverter valve
Pump
D.h.w. heat exchanger
D.h.w. circuit
C.h. circuit
Condensate drain pipe and trap
Flue pipes
Gas supply line
Power supply line
Defect #
The boiler does not supply d.h.w. (cold water from the tap). Regular operation in c/h mode even during a drawing off d.h.w.
J J J
On c/h mode the temperature of the main circuit reaches 75°Candthec/h
system does not heat. The boiler operates correctly on d.h.w. mode.
J J
Incorrect modulation J J J Noisy bolier J J The boiler operates correctly but the gas pressure to the burner remains at minimum.
J J
F
Poor d.h.w. temperature J J J J J
(9)
OF
F
Low d.h.w. flow rate J J J
---
Water leaks from the safety valve dur- ing operation on c/h
J J J J
---
Water leaks from the safety valve when the boiler is off.
J J J
Note Useful information can be obtained also from the optical indication given by the appliance oper- ation lights (see section 10.4). 1 Check for 230V~ between line (L) and neutral (N)
Verify the integrity of supply cable, plug and external fuses. Check the polarity of line and neutral connection
2 Verify the tightness of the gas supply pipe, the position of stop
valves.
Check the gas pressure at the inlet test point of the gas valve (see sect. 11.3) with the boiler at rest and during operation and compare it with the values given on the installation booklet.
3 Check for soundness and absence of obstructions. Verify that
the flue terminal is correctly installed (see clearances) and en- sure that exhaust gas is not sucked back by the boiler.
4 Check for soundness of the circuit and verify its correct filling
(see also installation manual).
5 A j a m m e d b y --- p a s s c o u l d c a u s e t h e o v e r --- h e a t i n g o f t h e m a i n
circuit and the intervention of the safety thermostat.
6Checktheminimum gas pressure at the outlet test point of the
gas valve (see sect. 11.3) and compare it with the value given on the installation booklet.
7 Verify the cleanness of injectors. 8 Check the pressurization of the expansion vessel. Refer to the
installation manual for proper values.
9 d.h.w. pressure too high or flow rate too high. If necessary in-
sert a flow rate limiter (14.6).