Page 1
WALL HUNG FAN FLUE
ROOM SEALED GAS COMBINATION BOILER
MODEL
British Gas Tested and Certified
G. C. No. 47 116 01
This boiler is for use with natural gas only
LEAVE THESE INSTRUCTIONS
ADJACENT TO THE GAS METER
BIASI U.K. Ltd
Unit 41, PlanetaryRoad IndustrialEstate, Neachells Lane
Willenhall, Wolverhampton WV13 3XB
Telephone: 01902 304400 --- Fax: 01902 304321
Page 2
TABLE OF CONTENTS
sect. subject page No.
1 General information 1. . ..... . . . . . . . . . . .
1.1 Overall view 1. . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2 Technical data 2. . . . . . . . . . . . . . . . . . . . . . . . .
1.3 Description 3. . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4 Flue pipes optional extras 3. . . . . . . . . . . . . .
1.5 Design principles and operating sequence 4
2 General requirements 6. . . . . . . . . . . . . . . . .
2.1 Related documents 6. . . . . . . . . . . . . . . . . . . .
2.2 Location of appliance 6.. . . . . . . . . . . . . . . . .
2.3 Flue system 6.. . . . . . . . . . . . . . . . . . . . . . . . . .
2.4 Gas supply 6. . . . . . . . . . . . . . . . . . . . . . . . . . .
2.5 Air supply 7. . . . . . . . . . . . . . . . . . . . . . . . . . . .
2.6 Water circulation (central heating) 7. . . . . . .
2.7 Domestic water 8. . . . . . . . . . . . . . . . . . . . . . .
2.8 Electrical supply 8. . . . . . . . . . . . . . . . . . . . . . .
3 Installation 9. . . . . . . . . . . . . . . . . . . . . . . . . . .
3.1 Delivery 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3.2 Measurements for installing the appliance 9
3.3 Assembling the wall mounting bracket 10. . .
3.4 Drilling the hole for the flue 10. . . . . . . . . . . . .
3.5 Unpacking the boiler 11. . . . . . . . . . . . . . . . . . .
3.6 Mounting the boiler on the bracket 12. . . . . . .
3.7 Mounting the flue exhaust pipes 13. . . . . . . . .
3.8 Flue terminal guard 15. . . . . . . . . . . . . . . . . . . .
3.9 Electrical connections 15. . . . . . . . . . . . . . . . . .
4 Commissioning 17. . . . . . . . . . . . . . . . . . . . . . .
4.1 Electrical installation 17. . . . . . . . . . . . . . . . . . .
4.2 Gas supply installation 17. . . . . . . . . . . . . . . . .
4.3 Filling the d.h.w. system 17. . . . . . . . . . . . . . . .
4.4 Initial filling of the system 17. . . . . . . . . . . . . . .
4.5 Setting the system pressure 18. . . . . . . . . . . .
4.6 Lighting the boiler 18. . . . . . . . . . . . . . . . . . . . .
4.7 Checking the gas pressure at the burner 19.
4.8 Checking the flue system 20. . . . . . . . . . . . . . .
4.9 Checking the full sequence control 20. . . . . .
4.10 Testing the d.h.w. system flow 20. . . . . . . . . . .
4.11 Selecting the pump operating modes 20. . . .
4.12 Instructing the user 21. . . . . . . . . . . . . . . . . . . .
5 Maintenance 22. . . . . . . . . . . . . . . . . . . . . . . . .
5.1 General 22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5.2 Recommended routine maintenance 22. . . . .
6 Servicing instructions 23. . . . . . . . . . . . . . . . .
6.1 Replacement of parts 23. . . . . . . . . . . . . . . . . .
6.2 To gain general access 23. . . . . . . . . . . . . . . . .
6.3 To drain the main circuit of the boiler 24. . . . .
6.4 To drain the d.h.w. circuit of the boiler 25. . . .
6.5 Setting gas pressures 25. . . . . . . . . . . . . . . . . .
6.6 Reducing the maximum output to meet
the central heating power requirements 25. .
6.7 Electronic regulation p.c.b. 26. . . . . . . . . . . . .
6.8 Full sequence control p.c.b. 26. . . . . . . . . . . .
6.9 Overheat thermostat 27. . . . . . . . . . . . . . . . . . .
6.10 Burner 27. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.11 Injectors 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.12 Ignition and/or detection electrodes 28. . . . . .
boiler 20/1 MFS
6.13 Insulation panels 28. . . . . . . . . . . . . . . . . . . . . .
6.14 Gas modulator cartridge 28. . . . . . . . . . . . . . . .
6.15 On---off operator coils 29.. . . . . . . . . . . . . . . . .
6.16 Gas modulator coil 29. . . . . . . . . . . . . . . . . . . .
6.17 Gas valve 30. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.18 Fan and venturi device 30. . . . . . . . . . . . . . . . .
6.19 Air pressure switch 31. . . . . . . . . . . . . . . . . . . .
6.20 Main heat exchanger 31.. . . . . . . . . . . . . . . . . .
6.21 Main circuit temperature probe 31. . . . . . . . . .
6.22 Pump 31. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.23 Main circuit flow switch 32. . . . . . . . . . . . . . . . .
6.24 Pump pressure switch 32. . . . . . . . . . . . . . . . .
6.25 Temperature---pressure gauge 33. . . . . . . . . .
6.26 By---pass 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.27 Automatic air release valve 33. . . . . . . . . . . . .
6.28 Expansion vessel 33. . . . . . . . . . . . . . . . . . . . . .
6.29 Safety valve 34. . . . . . . . . . . . . . . . . . . . . . . . . . .
6.30 3---way valve 34. . . . . . . . . . . . . . . . . . . . . . . . . .
6.31 D.h.w. heat exchanger 35. . . . . . . . . . . . . . . . .
6.32 D.h.w. temperature probe 37. . . . . . . . . . . . . . .
6.33 D.h.w. flow switch 37. . . . . . . . . . . . . . . . . . . . .
6.34 Water unit 38. . . . . . . . . . . . . . . . . . . . . . . . . . . .
6.35 O---rings position on the d.h.w. heat exch. 40
7 Fault finding 41. . . . . . . . . . . . . . . . . . . . . . . . . .
7.1 Fault finding diagrams 41. . . . . . . . . . . . . . . . .
7.2 Using the fault finding diagrams 41. . . . . . . . .
7.3 Special defects 41. . . . . . . . . . . . . . . . . . . . . . . .
7.4 Water leaks 41. . . . . . . . . . . . . . . . . . . . . . . . . . .
7.5 Difficulty in lighting the burner 41. . . . . . . . . . .
7.6 Incorrect combustion 41. . . . . . . . . . . . . . . . . .
7.7 Traces of gas or exhaust flues 41. . . . . . . . . . .
7.8 Appliance completely shut down 42. . . . . . . .
7.9 Fault of full sequence control p.c.b. 44. . . . . .
7.10 Fault on d.h.w. --- c.h. switching 46. . . . . . . . .
7.11 Fault on modulation 48. . . . . . . . . . . . . . . . . . . .
8 Electric diagrams 50. . . . . . . . . . . . . . . . . . . . .
8.1 General wiring layout 50. . . . . . . . . . . . . . . . . .
8.2 Functional flow diagrams 51.. . . . . . . . . . . . . .
9 Short spare parts list 56.. . . . . . . . . . . . . . . .
Page 3
1 GENERAL INFORMATION
1.1 Overall view
2524
23
22
21
20
19
18
15
(16)
(17)
36
1
35
14
13
2
3
4
5
6
7
8
9
10
11
12
34
33
Front view Rear view
26
27
30 282932 31
1 Main heat exchanger
2 Manual vent cock
3 Combustion chamber
4 Burner
5 Overheat thermostat (probe)
6 Detection electrode
7 Main circuit flow switch
8 Main circuit temperature probe
9 Thermometer probe
10 Pump
11 Pump plug
12 D.h.w. flow switch
13 Pressuretest point formeasuringoutlet pressure at
the gas valve
14 Pressure test point for measuring inlet pressure at
the gas valve
15 Control panel
16 Electronic regulation p.c.b.*
17 Full sequence control p.c.b.*
18 Wiring diagram
19 Gas valve
20 Gas modulator
21 Ignition electrode
22 Fan
23 Venturi device
rev. 17.09.93
24 Flue gas sampling point
25 Air pressure switch
26 Expansion vessel
27 Data badge
28 Gas inlet
29 Central heating (c.h.) water return
30 C.h. water flow
31 Domestic hot water (d.h.w.) inlet
32 D.h.w. outlet
33 3---way valve
34 D.h.w. heat exchanger
35 D.h.w. temperature probe
36 Automatic air release valve
37 Safety valve
38 Divertor on 3---way valve
39 Injector
40 Pump pressure switch
41 D.h.w. filter
42 D.h.w. flow limiter
43 By---pass
44 Main circuit drainage cock
45 D.h.w. circuit drainage cock
46 Air intake
47 Flue outlet
* component enclosed in the control panel.
1
Page 4
General information
1.2 Technical data
Heat input:
max 28,74 kW 98 080 Btu/h
min 12,40 kW 42 317 Btu/h
Heat output:
max 23.25 kW 79 344 Btu/h
min 8,71 kW 29 274 Btu/h
Central heating
Operating temperature:
max 85 °C
min 35 °C
Working pressure
max 3 bar 43,5 p.s.i.
Water content 6,25 lts. 1,37 gals.
Built in expansion vessel:
Total capacity 7,5 lts. 1,65 gals.
Pre---charge pressure 0,7 bar 10,1 p.s.i.
Available head at 1000 litres/hr (220 gals/hr)
3,2 m w.g. 126 ins w.g.
Gas requirements
max gas rate 2,79 m3/h 98,5 ft3/h
min gas rate 1,04 m3/h 36,7 ft3/h
Inlet pressure 20 mbar 7,9 in w.g.
Burner pressure:
max 9,7 mbar 3,9 in w.g.
min 1,4 mbar 0,6 in w.g.
Burner injectors 12 x 1.35
Component details
Gas control valve SIT 827 nova
Burner Polidoro
Electrical data
Electrical supply 240 V~
Frequency 50 Hz
Power consumption 150 W
External fuse rating 3 A
Internal fuse rating F1 0,08 A T**
Internal fuse rating F2 1,6 A T**
Temp. difference for
flow and return
20 °C
Flow rate of water
through the appliance
1 000 lts./h 220 gals./h
Max permissible coldwater capacity without additional
expansion vessel*
71 lts. 15,6 gals.
Domestic hot water
Operating temperature:
max 65 °C
min 37 °C
Working pressure:
max 10 bar 145 p.s.i.
min 0,2 bar 2,9 p.s.i.
Water content 0,38/lts. 0,08 gals.
flow rate:
min 2,0 lts./min 0,4 gals./min
30 °C rise 11,1 lts./min 2,4 gals./min
35 °C rise 9,5 lts./min 2,0 gals./min
40 °C rise 8,3 lts./min 1,8 gals./min
Connections
Gas connection 15 mm o.d.
c.h. flow 22 mm o.d.
c.h. return 22 mm o.d.
D.h.w. inlet 15 mm o.d.
D.h.w. outlet 15 mm o.d.
Safety discharge pipe 15 mm o.d.
Flue pipes specifications
Outer diameters:
flue exhaust pipe 60 mm 2,36 ins
Air intake pipe 100 mm 3,93 ins
Standard length 850 mm 33,46 ins
Maximum length *** 3 000 mm 118,11 ins
Other specifications
Height 967 mm 38,1 ins
Width 400 mm 15,7 ins
Depth 370 mm 14,5 ins
Dry weight 50 kg 110 lb
* If required an external expansion vessel can be fitted
** Spare fuses are available in housing of the electronic regulation p.c.b.
*** Using one or more horizontally elongated flue pipes kit (see sect. 1.4).
2
rev. 17.09.93
Page 5
General information
mbar ft. head
441,1
392,4
343,4
294,3
245,2
196,2
147,1
98,1
49,3
0
14,8
13,1
11,5
9,8
8,2
6,6
4,9
3,3
1,6
0
m w.g.
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500
fig. 1.1
Available pump head
The curve in fig. 1.1 shows the water pressure (head)
available to the central heating (c.h.) circuit as a function of flow; the load loss of the appliance has already
been subtracted.
1.3 Description
25
24
23
46
47
lts./h
4,4 5,13,62,92,21,50,70
gals./min5,54,74,03,32,51,81,10,4
It is produced as a room sealed category appliance
suitable for wall mounting applications only.
This boiler is suitable only for sealed systems.
It incorporates:
--- full sequence electronic ignition system
--- fan powered flue outlet with an annular co---axial
combustionair intake whichcanberotatedthrough
360 degrees
--- circulating pump
--- expansion vessel
--- temperature and pressure gauge
--- safety valve
--- 3---way valve
22
1
3
4
13
19
14
39
26
33
38
44
37
2928 32
34
36
30
2
7
12
10
42
41
43
40
45
31
fig. 1.2
The boiler 20/1 MFS is a combined central heating
(c.h.) and domestic hot water (d.h.w.) appliance.
rev. 17.09.93
1.4 Flue pipes optional extras
The following items are available.
The respective mounting instructions are included in
the carton containing the parts of the kit.
Horizontally elongated flue pipes
fig. 1.3
Morethan one sectionmay be used but the totallength
of the exhaust duct must not exceed 3 m (9,84 ft).
Every section allows to extend the duct by 825 mm
(32,48 ins).
3
Page 6
General information
Supplementary elbow
fig. 1.4
Asinglesupplementaryelbowonly, canbe usedduring
installation: the length of the exhaust duct (standard
elbow + the supplementary elbow included) must not
exceed1800 mm (5,9 ft).
Vertically elongated flue pipes
Main heat exchanger
Main circuit
flow switch
Pump
By---pass
C.h. circuit
fig. 1.6
During operation as a d.h.w.heater,the main water circuit is directed throughthe d.h.w.heat exchanger (see
fig. 1.7).
Main heat exchanger
fig. 1.5
The kit marked vertically elongated flue pipes allows to
rise the axis of the horizontal part of the exhaust duct.
1.5 Design principles and operating
sequence
Water system design
The basic purpose of a boiler is to generate heat
through the combustion of gas and to direct the heat
through a water circuit, as required.
A combination---type appliance allows the heat to be
usedeither for heating the environment and for heating
hot water for domestic use.
Main water circuit
This is an internal water circuit in the appliance which
passes through the main heat exchanger and absorbs
heat directly from the combustionof gas. The water in
thiscircuit is the same as the water that is circulated by
the pump and flows through the c.h. system.
The path of the water in the main water circuit can be
changed by a 3---way valve.The main water circuit is
connected to the c.h. circuit during operation with the
c.h. system (see fig. 1.6).
4
rev. 17.09.93
Flow switch
By---pass
Pump
D.h.w.heat
exchanger
D.h.w flow
switch
fig. 1.7
Also, a by---pass valve is installedin the main water circuit. The by---pass valve assures an adequate water
flow through the main heat exchanger regardless of
water flow conditionsin the water circuit, thus avoiding
damage due to temperature variations.
Safety devices
Inbothc.h.and d.h.w.modes safe operatingisensured
by a pump pressure switch and a flow switch on main
water circuit.
Ifthepressure in the mainwater circuitisinsufficientthe
pump pressure switch disconnects the supply to the
pump.
Ifthe flowrate inthe mainwater circuit is insufficientthe
flow switch on main water circuit disconnects the supply to the full sequence control p.c.b.
In both cases the boiler is stopped in order to prevent
damages.
A overheat thermostat disconnects the two ON---OFF
operators on the gas valve; as a result, the burner is
shutdown andthe shut-downwarning lightwillappear.
A safety valve is provided to relieve excess pressure
from the main circuit.
Theapplianceisequippedwith asafetysystem(venturi
deviceandairpressureswitch)whichsenses the velocity of the exhaust flues. If the air pressure switch does
Page 7
General information
not sense the correct velocity, the burner will shut
down.
Operating sequence on central heating mode
The function switch must be set on position.
The water in the main circuit is sent to the c.h. system
whenthe3---wayvalveisinthec.h. position. Inthisconfiguration, the divertor is in the upper position and the
d.h.w. heat exchanger circuit is cut out.
Theapplianceiscontrolledbyan electronicthermostat;
water deliverytemperature canbe adjusted from 35 °C
to 85 °C.
When heat is requested, a command reaches the full
sequence control p.c.b.; this command starts the fan,
which switches the air pressure switch. After the air
pressure switch has been switched, the combustion
chamberispurgedofanyresidualunburnedgasses for
a few seconds. Next , the lighting cycle begins with a
spark from the ignition electrode; at the same time,
electricalpowerisfed tothetwoON---OFFoperatorson
the gas valve.
If the flame detection electrode does not sense the
flamewithin 4 seconds from the beginningof the cycle,
the full sequence control p.c.b. interrupts the lighting
cycle,the electric spark isshut off and thepower isdisconnectedfromthe twoON---OFFoperatorsonthe gas
valve; as a result, the burner is shut down.
At this point, the shut down warning light appears and
the reset push---button must be pressed to restart the
lighting cycle.
If the detection electrode senses flames within 4 secondsfrom the beginningof the cycle, the full sequence
control p.c.b. interrupts the electric sparks and holds
the burner alight.
At the same time, the temperature ofthe heating circuit
ismeasured by the maincircuit temperature probe and
this temperature is compared with the value set on the
c.h. temperature adjustment ( ).
After lighting has been accomplished, the amount of
flow from the gas valve is determined by the electronic
regulation p.c.b.:
--- when the temperature of the c.h. water is less than
thepreset temperaturebya ?tvalue(differencebetweenoutput andinput temperature)between 6 °C
and 15 °C, the appliance willsupply heating power
which ranges from 35 to 100% of its maximum capacity;
--- when the temperature of the c.h.water is less than
the preset temperature by a ?t value which is less
than 6 °C, the appliance will supply its minimum
heating power (35% of its maximum heating
power);
--- if the minimum power is greater than the heat
emitted from the radiators, the burner will shut
down.
Heating power can be varied from 35 to 100% of the
maximum rated power.
Operating sequence on d.h.w. mode
Whenevera d.h.w.tapis opened,thed.h.w.flowswitch
onthe d.h.w. systemis activated and a signal is sent to
the electronic regulation p.c.b. This signal moves the
shutter on the 3---way valve and thus closes the c.h.
water circuit and opens the d.h.w. heat exchanger circuit.
The burner will operate at nominal power, or at a power
rating which keeps d.h.w. at the constant temperature
desired(as long asthedemand forheatingpowerdoes
not exceed the nominal power supplied by the boiler).
Thus, burner operation depends on the amount of
d.h.w.usedandthetemperaturewhichhas been seton
the d.h.w. temperature adjustment ( ).
D.h.w. only operation
Whenthefunction switchisseton position,thec.h.
adjustment system is deactivated, the 3---way valve is
nolonger actuated, the shutter closes water deliveryto
the c.h. circuitand opens deliverytothe d.h.w.heat exchanger. Whend.h.w.iswithdrawn from the d.h.w.system, operation of the appliance will be the same as
operation with the function switch set on position.
rev. 17.09.93
5
Page 8
2 GENERAL REQUIREMENTS
This appliance must be installed by a competent
person in accordance with the Gas Safety (installation & Use) Regulations 1984.
2.1 Related documents
Theinstallationofthisappliancemustbe inaccordance
withthe relevantrequirementsof theGasSafety(Installation & Use) Regulations (1984), the Local Building
Regulations, the current I.E.E . Wiring Regulations, the
by---laws of the local water undertaking, and in Scotland, in accordance with the Building Standards (Scotland) Regulation. Health and safety document n° 635
”Electricity at work regs. 1989”.
It should be in accordance also with the following British Standard Codes of Practice:
Low pressure installation pipes
Boilers of rated input
not exceeding 60 kW
Forced circulation hot
water systems
Installation of gas hot
water supplies for domestic purposes
(2ndfamily gases)
Flues BS 5540---1 1990
BS 6891 1988
BS 6798 1987
BS 5449 1990
BS 5546 1990
The location must permit the provision of an adequate
flue and termination.
For unusual locations special procedures may be
necessaryand BS6798---1987givesdetailedguidance
on this aspect.
A compartment used to enclosethe appliance must be
designed specifically for this purpose.
This appliance is not suitable for external installation.
2.3 Flue system
The provision for satisfactory flue termination must be
made as described in BS 5440---1.
Theappliancemustbeinstalledsothatthe flueterminal
is exposed to external air.
It must not be installed so that the terminal discharges
intoanother roomorspaceas anouthouseorlean---to.
It is important that the position of the terminal allows a
free passage of air across at all times.
The terminal should be located with due regard for the
damage or discoloration that might occur to building
products in the vicinity.
In cold and/or humid weather water vapour may condense on leaving the flue terminal; the effect of such
”steaming” must be considered.
The minimum acceptable spacing from the terminalto
obstructions and ventilation openings are specified in
fig. 2.2.
Air supply BS 5540---2 1989
2.2 Location of appliance
The appliance may be installedin any room or internal
space, although particular attention is drawn to the requirements of the current I.E .E. Wiring Regulations,
andin Scotland, theelectricalprovisionsoftheBuilding
Regulationsapplicable in Scotland, with respect to the
installation of the combined appliance in a room containing a bath or shower.
Where a room--sealed appliance is installed in a
room containing a bath or shower, any electrical
switchor appliance control, utilisingmains electricity should be so situated that it cannot be touched
by a person using the bath or shower.
Thelocationmust permitan adequate space for servicing and air circulation around the appliance
(see fig. 2.1).
a
d
c
fig. 2.1
6
b
a
b
c
d
155 mm
130 mm
500 mm
50 mm
6,1 ins
5,1 ins
19,7 ins
1,9 ins
rev. 17.09.93
BC
F
D
HI
J
A
E
fig. 2.2
Terminal position mm
A Directly below a open window or other opening 300. . . . . . . .
B Below gutters, solid pipes or drain pipes 75. . . . . . . . . . . . . . .
C Below eaves 200. . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D Below balconies or car port roof 200. . . . . . . . . . . . . . . . . . . . .
E F romvertical drain pipes and soil pipes 75. . . . . . . . . . . . . . . .
F From internal or external corners 300. . . . . . . . . . . . . . . . . . . .
G Above ground or below balcony level 300. . . . . . . . . . . . . . . .
H From a surface facing a terminal 600. . . . . . . . . . . . . . . . . . . . .
I From a terminal facing a terminal 1200. . . . . . . . . . . . . . . . . . .
J From an opening in the car port.. .
(e.g. door,window) into dwelling 1 200. . . . . . . . . . . . . . .
K V ertically from a terminal in the same wall 1500. . . . . . . . . . .
L Horizontally from a terminal in the same wall 300. . . . . . . . . . .
F
G
KL
G
2.4 Gas supply
Gas meter is connected to the service pipe by the local
gas region or a local gas region contractor.
If the gas supply for the boiler serves other appliances
ensure that an adequate supply is available both to the
Page 9
General requirements
boiler and the other appliance when they are in use at
the same time.
Pipework must be of adequate size. Pipes of a smaller
sizethantheboilerinletconnectionshouldnotbeused.
Installation pipes should be fitted in accordance with
BS 6891---1988 and thecompleteinstallationshouldbe
tested for soundness.
2.5 Air supply
The room in which the boiler is installed does not require a purpose provided air vent.
If installed in a cupboard or compartment, ventilation is
also required for cooling.
Recommendations for air supply are detailed in
BS 5440---2 .
2.6 Water circulation (central heating)
Detailedrecommendationsare giveninBS6798---1987
and BS 5449---1 1990; the following notes are given for
general guidance.
Pipework
CoppertubingtoBS 2871---1 1977 isrecommendedfor
waterpipes. Jointingshouldbe either withcapillarysoldered or with compression fittings.
Wherepossiblepipes should havea gradientto ensure
air is carried naturally to air release points and water
flows naturally to drain taps.
The appliance has a built---in automatic air release
valve anyway, it should be ensured as far as possible
that the appliance heat exchanger is not a natural col-
lecting point for air.
Except where providing useful heat, pipes should be
insulated to prevent heat loss and to avoid freezing.
Particular attention should be paid to pipes passing
through ventilated spaces in roofs and under floors.
By--pass
The appliance includes an automatic by---pass valve
which protects the main heat exchanger in case of re-
ducedorinterruptedwatercirculationthroughtheheat-
ing system due to the closing of thermostatic valves or
cock---type valves within the system.
The by---pass iscalibrated to assure a minimum flowof
500---600 lts/hr through the main heat exchanger.
System design
This boiler is suitable only for sealed systems.
A typical lay---out is illustrated in the following figure.
Cold water inlet
Gas supply pipe
Shower
Sink
fig. 2.3
Drain tap
(at lowest point)
7
rev. 17.09.93
Page 10
General requirements
Thesemustbelocatedinaccessiblepositionstopermit
the draining of the whole systems. The taps must be
at least 15 mm nominal size and manufactured in accordance with BS 2870 1980.
Air release points
These must be fitted at all high points where air will
natural collect and must be sited to facilitate complete
fitting of the system.
The appliance has an integral sealed expansion vessel
to accommodate the increase of water volume when
the system is heated.
It can accept up to 7 lts (1,5 gals.) of expansion water.
If the heating circuit has an unusually high water con-
tent, calculate the total expansion and add additional
sealed expansion vessel with adequate capacity.
Mains water feed: central heating
There must be no direct connection to the mains water
supplyeven througha nonreturn valve, withoutthe approval of the Local Water Authority.
Filling
A method for initially filling the system and replacing
water lost during servicing must be provided and it
must comply with local water authority regulations.
A possible method is shown in fig. 2.4.
The installer should ensure that no leaks exist as frequent fillingof the system couldcause premature scaling of the heat exchanger.
2.7 Domestic water
Thedomesticwater must be inaccordance withtherelevant recommendations of BS 5546. Copper tubing to
BS 2871---1 is recommended for water carrying pipework and must be use for pipework carrying potable
water.
2.8 Electrical supply
Warning, this appliance must be earthed.
External wiring to the appliance must be carried outby
acompetent person andbe in accordancewiththe current I.E.E. Regulations and local regulations which
apply.
The boiler 20/1 MFS is supplied for connection to a
240 V~ 50Hz supply. The supply must be fused at 3A.
Themethodof connectionto the electricitysupplymust
facilitate complete electrical isolation of the appliance
bythe use ofa fused doublepoleisolatorhaving acontact separation of at least 3 mm in all poles or alternatively, by the use of a 3A fused three pin plug and unswitched shuttered socket outlet both complying with
BS 1363.
Thepointofconnectionto the electricitysupplymustbe
readilyaccessibleand adjacenttotheapplianceexcept
were the appliance is installed in a bathroom this must
be sited outside the bathroom.
C.h. return Cold water inlet
fig. 2.4
Wall mounting
bracket
Temporary hose
8
rev. 17.09.93
Page 11
3 INSTALLATION
3.1 Delivery
There will be 3 items:
1 the boiler fully assembled;
2 the wall mounting bracket with cocks and pipes;
3 Standardflue assembly whichincludeflue pipesand90° elbow.
3.2 Measurements for installing the appliance
61 (2,40)
Wall mounting bracket
400 (15,7)
853 (33,6)
155 (6,1)500 (19,7)
50 130
(5,12)(2)
252 (9,92)
a b c d e
f
187 (7,36) 213 (8,38)
Front view Top view
a --- safety valve discharge pipe
b --- gas
c --- c.h. water return
d --- c.h. water flow
e --- d.h.w. inlet
f --- d.h.w. outlet
78 (3,07)
50 130
180 (7)
(5,12)(2)
Clearances required for servicing
83 (3,27)
Wall mounting bracket
122 (4,80)
228 (8,97)
25
(1)54(1,12)49(1,93)45(1,77)40(1,57)
All measurements are in millimetres (inches in brackets)
rev. 17.09.93
145
(5,71)
9
Page 12
installation
3.3 Assembling the wall mounting bracket
The carton marked wall mounting bracket contains the following:
1 mounting bracket;
2 1/2” cock for d.h.w. inlet;
3 3/4” cocks for c.h. flow and return;
4 1/2” nipples for d.h.w. and safety valve outlet;
5 3/4” gaskets;
6 3/4” nuts for mounting 3/4”cocks and gas pipe;
7 3/4” nipple for c.h. return;
8 ø 15 mm o.d.pipe for safety valve discharge;
9 ø 22 mm o.d. pipe for c.h. return with 3/4” connector nut;
10 ø 22 mm o.d. pipe for c.h. flow with 3/4” connector nut;
11 ø 15 mm o.d.pipes for d.h.w circuit;
12 ø 15 mm o.d.pipe for gas inlet;
13 c.h. return pipe with safety valve connection;
14 safety valve;
15 1/2” nuts for mounting the 1/2” cock and nipple;
16 1/2” gaskets;
17 1/2” connector nuts;
18 15 mm compression fitting cock for gas inlet.
--- Position the mounting bracket on the wall. Use a spirit level to
make sure that the support is level;
--- mark the attachment points through the holes indicated;
--- remove the wall mounting bracket and drill holes in the wall at
the points marked;
--- use screws with wall plugs ø 8 mm to attach the wall mounting
bracket to wall;
18
17
16
15
14
13
12
1
2
3
4
5
6
7
8
9
10
11
1
3.4 Drilling the hole for the flue
--- Drill a hole with a diameter of at least 110 mm (4,33 ins) in the
wall; for correct position see sect. 3.2.
Drill the hole in the direction of the flue exhaust pipe so that the
duct will have a slight downward inclination to the outside;
--- mount the cocks and fittings on the bottomof the wall mounting
bracket and tighten with the nuts;
--- use the connector nuts to connect the pipes to their respective
cocks.
Be sure to use the correct gaskets when installing the pipes;
--- connect valves and pipes from right to left;
10
rev. 17.09.93
Wall mounting bracket (1)
1113 10
5
6
(top view)
17
16
15
423712
Page 13
Installation
--- mountthecockforgasinlet(18)and the 3/4”cock for c.h.return
(3). Be sure to use the correct gaskets.
--- mount the pipe for c.h. return (9);
12
18
13
Wall mounting
bracket (1)
5
(front view)
--- mount the safety valve (14) on the c.h. return pipe (13) with a
1/2” gasket. The valve must be mounted with its outlet towards
the left hand.
--- Mount the 1/2” nipple (4) and the pipe for the safety valve discharge (8) with the correct gaskets as indicated. Connect discharge pipe to enable it to discharge externally at low level;
--- connect cocks to corresponding pipes within the appliance
using the correct washers supplied;
--- completethe installationconnecting thepipes tothe otherparts
of the plant. Make water heating and gas connections to the
appliance.
3.5 Unpacking the boiler
--- Open the side of the carton marked opening side;
3
17164 14
8
9
Towards the
safety valve.
4
13
--- overturn the carton keeping the flaps open;
rev. 17.09.93
11
Page 14
installation
--- lift up the carton;
--- rest the boiler on the floor and remove the polystyrene guards.
3.6 Mounting the boiler on the bracket
--- Remove the protection caps from the pipes on the boiler;
--- carefully clean the cocks and connections mounted on the wall
mounting bracket;
--- hang the appliance on the bracket;
--- remove the lower protection plate (sect. 6.2);
--- install connectors on the pipes (use the original gaskets
supplied with the wall mounting bracket);
--- tighten the connectors securely;
--- re---install the lower protection plate.
12
rev. 17.09.93
Page 15
Installation
3.7 Mounting the flue exhaust pipes
Open the carton marked standard flue exhaust pipes.
It contains the following:
19 flue exhaust pipe with wind---resistant terminal;
20 pipe support
21 self---tapping screws 3,5 x 19 mm;
22 springs for the tightening band;
23 gasket tightening band;
24 gasket which seals the elbow to the flue duct;
25 gasket which seals the elbow to the surface of the appliance;
26 self---tapping screws 4,8 x 13 mm;
27 90° elbow;
28 suction pipe --- ø100 mm;
29 wall gaskets;
30 self---tapping screws 4,8 x 13 mm.
Cutting the flue exhaust pipes
Ifyourparticularinstallationrequiresyoutoshortentheduct,seethe
following instructions for cutting measures.
If you need to extend the flue duct or change its direction, optional
kits are available (sect. 1.4).
All measures are in millimetres (inches in brackets).
Both pipes must be cut on the side facing the elbow.
28
27
26
29
25
24
23
30
22
19
20
21
Rear outlet
Ls = Lx + 173 (6,81)
Le = Lx + 322 (12,68)
Ls max = 775 (30,51)
Le max = 928 (36,53)
Right side outlet
L1 min = 130 (5,11)
Ls = Lx + L1 + 134 (5,27)
Le = Lx + L1 + 287 (11,30)
Ls max = 775 (30,51)
Le max = 928 (36,53)
Left side outlet
L2 min = 50 (1,97)
Ls = Lx + L2 + 108 (4,25)
Le = Lx + L2 + 261 (10,27)
Ls max = 775 (30,51)
Le max = 928 (36,53)
6 (0,23)
61 (2,40)
Wall mounting
bracket
6 (0,23)
61 (2,40)
Wall mounting
bracket
20 (0,78)
Lx
Ls
Le
Lx
20 (0,78)
Ls
Le
Lx
Ls
Le
L
1
L
2
20 (0,78)
6 (0,23)
Wall mounting
bracket
61 (2,40)
rev. 17.09.93
13
Page 16
installation
Mounting operations
--- Insert the exhaust pipe into the suction pipe so that the wind--resistantterminalcontacts the rimwhich is located onthe inside
of the suction pipe;
--- introduce the pipe assembly, together with wind---resistant terminal, into the hole you have drilled in the wall.
A20mm (0,78ins)lengthof the suctionpipemustprotrudefrom
the wall;
--- mount the wall gaskets on the pipe;
--- positionthe gaskets so when the pipeis pulled back they make
good seal against the wall;
--- insert the pipe support;
--- insert the suction pipe on the tightening band;
--- install the gasket which seals the elbow to the duct by placing
thelarger internal diameterof the gasketon theair suctionpipe;
28
20
19
28
2929
20 mm
(0,78 ins)
19
19
--- place the gasket on the surface of the appliance;
--- installtheelbowonthesupport;besure thatthefollowingconditions are met:
make sure that the flue exhaust pipe is firmly inserted into the
elbow;
besure that a distance of6 mm (0,23ins) has been left between
the suction pipe and the elbow.
The purpose of this space is to allow the elbow to be removed
for maintenance after the pipe has been enclosed in the wall.
Therefore, never push the suction pipe into the elbow;
--- use the screws to attach the elbow to the surface of the
appliance;
--- use the gasket you previously installed to seal the connection
between the elbow and the duct;
--- use the gasket tightening band with springs and screws to
tighten the gasket;
--- make two ø 3,7 mm (0,14 ins) holes; one on the elbow and the
other on the intake pipe at the same level as the holes on the
gasket tightening band;
--- use the screws supplied with the kit to connect the elbow, the
band and the pipe together.
26
25
24
27
27
28
6 mm
(0,22 ins)
23
30
19
24
28
21
14
rev. 17.09.93
Page 17
Installation
3.8 Flue terminal guard
Where codes of practise dictate a suitable guard should be fitted.
A suitable guard is available from:
TOWER FLUE COMPONENTS
Morley Road
Tonbridge
Kent TN9 1RA
When ordering guard, quote appliance model number.
The guard should be fitted centrally over the terminal.
3.9 Electrical connections
Connecting to the electricity supply
WARNING -- THIS APPLIANCE MUST BE EARTHED
The appliance is delivered with a flexible cable for electrical supply.
The cable allows the electrical connection as detailed in sect. 2.8.
Theelectricalsupplycable is stored insidethe applianceinthe lower
rightzone of the control panel and it is marked with a label stuck on
its edge.
Togain accessto theelectrical supplycable, removethe frontpanel
of the case and lower the control panel as explained in sect. 6.2.
--- Pass the cables (electrical supply cable and external controls
cable) through the rubber grommets fitted on the bracket indicated;
--- make sure allcables to the appliance are detail route away from
sharp edges and hot surfaces.
--- fit the lower protection plate.
Replacing the electrical supply cable
To replace the electrical supply cable proceed as follows:
--- remove the front panel of the case (sect.6.2)
--- unscrew the six screws ”A” and remove the service access
doors;
C
--- loosenthe screws ”B” of the main terminalblock (marked Land
N) and the screw ”C” of the earth terminal;
--- loosen the screws ”D” and pull the cable removing it from the
clamp seat;
--- lower the control panel (sect.6.2); C
C
C
B
C
C
C
rev. 17.09.93
D D
15
Page 18
installation
--- unscrew the four screws ”E” and remove the cover on the full
sequence control p.c.b.
--- remove the cable sliding it through the rubber grommet ”F”;
--- insert the new cable. A PVC insulated flexible cable must be
used. It must be a 3 core of size 0.75 mm2(24x0.2 mm) to BS
6500 table 16;
--- connect the cable to the terminals marked as follows:
L ---
Screws ”B”
--- The cable must be secured and connected so that should the
cable slip from the anchorage the current carrying conductors
become taut before the earthing conductor.
Connecting the external controls
(room thermostat, timeclock)
WARNING -- EXTERNAL CONTROL LINES MUST BE INSULATED FROM ELECTRICAL SUPPLY LINES.
Ifcontrolsexternalto the appliancearerequired, design of theexternalelectrical circuitsshould be undertaken by a competentperson.
Itis essential thatallexternal controlcircuitsandwiring iswiredfrom
the same electrical isolator as serves the appliance. Factory fitted
internalwiring must notbe disturbed when wiring external controls.
Brown or Red wire (live)
N ---
Blue or Black wire (neutral)
Green/Yellow or Green wire (earth)Screw ”C”
E
E
F
E
E
To connect an external control:
1 remove the front panel of the case and lower the control panel
(see sect. 6.2);
2 open the external control box removing the two screws indi-
cated;
3 removethe electric linkbetween TT and TCon the external con-
trol terminal block;
4 connect the external control as shown in the following figures.
If requested, external control must be earthed.
Timeclocks should be voltage free connections.
Connecting a ”simple contact” room thermostat.
Connecting a room thermostat with delay resistor.
TT
TR
TC
External control box
TT
TR
TC
External control box
Connecting a timeclock.
Do not insert any internal links on time locks.
Doing so may invalidate guarantee.
16
rev. 17.09.93
TT
TR
TC
External control box
N
L
M
Page 19
4 COMMISSIONING
4.1 Electrical installation
Preliminaryelectrical system checks to ensure electricalsafetyshall
be carried out by a competent person. I.e. polarity, earth continuity,
resistance to earth and short circuit.
If a fault has occurredon appliancethefaultfinding procedure should
be followed as specifiedundertheservicingsection of thisdocument.
4.2 Gas supply installation
1 Inspect the entire installation including the gas meter, test for
soundness and purge, all as described in BS 6891;
2 open the gas cock (drawn with the knob in ”open” position) on
theapplianceand check the gas connector onthe appliancefor
leaks.
4.3 Filling the d.h.w. system
1 Close all hot water draw---off taps;
2 open the cold water inlet cock as indicated;
3 slowly open each draw---off tap and close it only when clear
water, free of bubbles, flows out.
4.4 Initial filling of the system
1 Open central heating flow and return cocks as indicated;
2 unscrew the cap on the automatic air release valve one full turn
and leave open permanently;
3 close all air release valves on central heating system;
4 gradually open stopcock at the filling point connection to the
central heating system until water is heard to flow;do not open
fully;
5 openeach air release tap startingwith the lowerpoint and close
it only when clear water, free of bubbles, flows out;
6 remove the front panel of the case, the lower protection plate
and lower the control panel (sect. 6.2);
7 purge the air from the pump by unscrewing the pump plug indi-
cated;releasethe pumpbyturning therotorinthe directionindi-
cated by the arrow on the information plate;
8 close the pump plug;
9 continuefillingthesystemuntilat least 1,5bar (21,3 p.s.i.)regis-
ters on temperature---pressure gauge;
10 inspect the system for water soundness and remedy any leaks
discovered.
11 make sure that the control lever on the 3---way valve (bottom
side of appliance) is positioned to the right;
rev. 17.09.93
17
Page 20
Commissioning
When the installation and filling are completed turn on the central heating system (sect. 4.6) and run it until the temperature
hasreached theboiler operating temperature.The systemmust
then be immediately flushed through.
The flushingprocedure must be in line withBS7593: 1992Treat-
ment of Water in Domestic Hot Water Central Heating Systems.
This procedure must be repeated twice more.
During thisoperation we highly recommend the use of a central
heating flushing detergent, whose function it is to dissolve any
foreign matter which may be in the system. i.e. Fernox Superfloc.
We also recommend the use of an inhibitor in the system such
as Fernox MB1 universal.
The above operation could save the invalidation of your boilers
guarantee and will also prevent problems which you may experience in the future if an inhibitor is not used.
4.5 Setting the system pressure
The actual reading should ideally be 1,5 bar (21,3 psi).
4.6 Lighting the boiler
If external controls are fitted (e. g. Timeclock,room thermostat) ensure they ”call for heat”.
Commissioning operations will be easier if controls are disconnected and terminals TT and TC are linked
(see sect. 3.9).
1 Switch on the mains electricity and turn the function switch ”A”
as indicated.
The boiler willnow go through an ignitionsequence and the burner
will light.
If during the ignition attempt period (4 secs. approx.) the boiler falls
to light, the full sequence control p.c.b. will go to lockout and the
shut---down warning light ”B” will appears.
To reset the boiler depress the reset push button ”C” marked with
the symbol:
A
B
C
18
rev. 17.09.93
Page 21
Commissioning
4.7 Checking the gas pressure at the burner
Checking maximum and minimum pressure levels
1 Remove the front panel of the case and lower the control panel
(sect. 6.2);
2 remove the screw (indicated) on the pressure test point for
measuring outlet pressure at the gas valve and fit a pressure
gauge using a hose;
3 open the hot water tap fully;
4 turn the function switch as indicated;
5 set the d.h.w. temperature adjustment and the c.h. temperature
adjustment to their maximum position;
6 checkthemaximumgaspressure and comparethevalueonthe
manometerwith the values onsect. 1.2 (technical data) atpage
2;
If the pressure is wrong it should be adjusted as instructed in
sect. 6.5 at page 25;
7 checkthemaximumgasflowat the gasmeterand comparewith
the values on sect. 1.2 (technical data) at page 2;
8 turn off the electricity supply;
9 disconnect the gas modulator removing a connector (indi-
cated);
10 turn the function switch as shown at step 4;
11 checkthe minimumgas pressure and compare thevalue onthe
manometerwith the values onsect. 1.2 (technical data) atpage
2;
If the pressure is wrong it should be adjusted as instructed in
section 6.5 at page 25;
12 switch off the appliance and re---connect the line to the gas
modulator;
13 close the domestic hot water cock.
rev. 17.09.93
19
Page 22
Commissioning
.
Btu/h
k
W
Checking the maximum rate for central heating
14 Turn the function switch as shown in sect. 4.6;
15 check the maximum gas pressure and refer to the diagram
shown here to determine pressure for the heating output you
need;
If the pressure is wrong it should be adjusted as instructed in
sect. 6.6 at page 25;
16 switch off the appliance;
17 securely close the pressure test point, close the control panel
and fit the case.
4.8 Checking the flue system
The flue system should be visually checked for soundness. Check
all clamps, gaskets and fixings are secure and tight.
To check the exhaust gas, remove the screw indicated and connect
the analyzer to the flue gas sampling point.
78 491
71 666
64 841
58 015
51 190
44 365
37 539
30 714
23 889
23
21
19
17
15
13
11
9
7
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
0,4 0,8 1,2 1,6 2,0 2,4 2,8 3,2 3,6 4,00
mbar
ins.w.g
4.9 Checking the full sequence control
With the burner on high flame close the gas cock (drawn with the
knob in ”close”position) turning the screw in a clockwise direction;
about 4 seconds after, the shut---down warning light must appear.
To reset the boiler depress the reset push button marked with the
symbol:
4.10 Testing the d.h.w. system flow
This appliance does not require particular regulations on d.h.w.
function;
1 turn the function switch as indicated and check the switching
flow rate that should be at minimum 2 lts/min (0,44 gals/min);
4.11 Selecting the pump operating modes
Three operating modes forthe pump are availableduring c.h.operation.
These modes are selected by installing the electric link connection
”A” between certain terminals on the main terminal block which is
located on the electronic regulation p.c.b.
Duringd.h.w.heatingoperationthe pumpisactivatedautomatically.
To gain access to the terminal block remove the front panel of the
case and remove the service access door (sect. 6.2).
A
20
rev. 17.09.93
Page 23
Commissioning
The pump may operate when activated by an external control
device (room thermostat and/or timeclock).
This operating mode is obtained by connecting a link between terminals P2 and PC.
The appliance is tested and delivered in this operating mode
The pump may only operate when a request for heat lights up
the main burner.
This operating mode is obtained by connecting a link between terminals P1 and PC.
The pump may continuously operate.
This operating mode is obtained by connecting a link between terminals P3 and PC.
4.12 Instructing the user
1 Handover the User’s guide supplied with the appliance and ex-
plain how to use the unit in both c.h. and d.h.w. modes;
2 take the User step by step through the lighting instructions;
3 show the User how to switch off the appliance quickly and indi-
cate the position of the electric supply isolator;
4 explain the proper use and adjustment of all system controls;
this will ensure the greatest possible fuel economy;
5 explain the function and use of the function switch;
6 explain and demonstrate the function of time and temperature
controls (if fitted);
7 explain how to turn off the appliance for both short and long
periods and advise on the precautions necessary to prevent
damage should the appliance be inoperative when freezing
conditions may occur;
8 finally,advisethe User that,forcontinuedsafeandefficientoper-
ation,the appliancemust be servicedby acompetent personat
least once a year.
P3P2PCP1NL
P3P2PCP1NL
P3P2PCP1NL
rev. 17.09.93
21
Page 24
5 MAINTENANCE
5.1 General
To ensure efficient safe operation of the appliance it is
necessary to carry out routine maintenance at regular
intervals.
The frequency of servicing will depend upon the particular installation conditions and the use to which the
boiler is put, but, in general, once per year should be
adequate.
Thefollowingnotes applyto the appliance but it should
be remembered that attention must be also paid to the
central heating and domestic hot water circuits with
special attention to radiator valves, thermostats,
clocks, leaking hot water taps etc.
WARNING
Before starting any servicing work, switch--off the
electrical supply or disconnect the plug at the main
isolating switch and socket (if a switch is used remove the fuse).
Afteranyserviceonelectricalcomponentsfollowtheinstructions in the British Gas Multi Meter Book for preliminary electrical checks; in particular:
earth continuity;
polarity;
resistance to earth.
5.2 Recommended routine maintenance
Thefollowingprocedures shouldbe carriedout atleast
once per year:
1 verify that the the electrical connections, the flue
pipework and the case are in good conditions;
2 inspect ventilation arrangements as explained in
section 2.5 to ensure no alterations have been
made since installation;
3 switch---offthe electricalsupplyandremovethethe
front panel of the case (section 6.2);
4 switch---on the electrical supply and run the boiler
for few minutes in the d.h.w. mode;
5 check that the flame covers all the flame ports and
isofa lightbluecolour. Yellowflames and excessive
lifting of flames indicate poor combustion.
6 Visually check the flue system checked for sound-
ness. Check allclamps, gaskets and fixings are secure and tight. To check the exhaust gas, remove
the screw indicated infig. 5.1 and connect the analyzer to the flue gas sampling point.
fig. 5.1
To inspect and clean the appliance
7 switch---off the electricalsupply,removethesealed
chamber cover and openthe combustionchamber
(section 6.2);
8 if during initial check any combustion irregularity
was suspected, remove the burner and the injectors (sections 6.10 and 6.11. Clean or replace if
necessary;
9 inspect the main heat exchanger for any deposits
of sooty. If cleaningis necessary place a cloth over
the burner to catch debris and clean the main heat
exchanger using a soft brush.
Do not use brushes with metallic bristles;
10 inspect the combustion chamber panels. If any
panels are damaged these should be replaced;
11 examine the fan for any mechanical damage and
check to ensure free running of the fan motor;
12 check sealing gaskets and replace if damaged;
13 replaceall parts inreverse order with the exception
of the case and the control panel;
14 undertakea completecommissioningcheckas de-
tailed in section 4;
15 close---up the control panel and the case;
16 clean the case using a soft cloth.
22
rev. 17.09.93
Page 25
6 SERVICING INSTRUCTIONS
6.1 Replacement of parts
Thelifeof individualcomponentsvaries and they willneed servicing
as and when faults develop.
The fault finding sequence charts in chapter 7 will serve to locate
which component is the cause of any malfunction, and instructions
for removal, inspection and replacement of the individual parts are
given in the following pages.
6.2 To gain general access
All testing and maintenance operations on the water heater require
the removal of the panels which make up the case. These operations may also require the lowering of the control panel.
Removing the case
The front panel of the case is attached to the control panel by two
screws.
To remove the front panel, proceed as follows:
1 remove the mounting screws indicated;
2 move the lower part of the front panel away from the unit;
3 raise the panel slightly and then remove it.
To remove the side panels remove the front panel as explained
above, loosen the lower screws ”A” and proceed in the same way
as for the front panel.
Removing the lower protection plate
To remove the lower protection plate, loosen the screws ”B” and
move the plate toward the wall.
Lowering the control panel
Thecontrolpanelisheldinitsnormalpositionbytwo screwslocated
on the left---hand and right---hand sides of the panel.
To lower the control panel proceed as follows:
1 remove the front panel of the case;
2 hold the control panel in position and remove the two screws
indicated.
3 lower the panel.
Removing the service access doors
To remove the service access doors proceed as follows:
1 remove the front panel of the case;
2 set the d.h.w temperatureadjustment andthe c.h. temperature
adjustment to their maximum posiition;
3 set the function switch on ”O” position;
4 unscrew the six screws ”C” and remove the service access
doors;
B
A
B
A
C
C
C
B
A
B
A
B
C
C
C
Do not change position of knobs during service operations.
rev. 17.09.93
23
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Servicing instructions
Removing the sealed chamber cover
To open the sealed chamber remove the front panel and the right
panelofthe casethen turnthe fourclamps as indicatedand remove
the cover.
When replacing the sealed chamber cover ensure that the seal is
made good. If adjustments isneeded this can be done by adjusting
the clamps.
Opening the combustion chamber
1 Remove the four screws ”D”;
2 rise the panel and remove it.
6.3 To drain the main circuit of the boiler
1 Close c.h. flow and return cocks;
2 open the main circuit drainage cock indicated;
3 tospeed drainage remove the front panel and the right panelof
the case, the sealed chamber cover (sect. 6.2) and then open
themanual vent cock placed nearthe mainheat exchangerinlet
connector.
D
D
D
D
24
rev. 17.09.93
Page 27
Servicing instructions
6.4 To drain the d.h.w. circuit of the boiler
1 Close the cold water inlet cock;
2 open the drain tap of d.h.w. system or a draw---off tap;
3 open the d.h.w. circuit drainage cock indicated.
6.5 Setting gas pressures
IMPORTANT
minimum gas pressure mut be set after maximum setting.
1 Open the boiler and operate as explainedin sect. 4.7 from step
1 to step 5;
Setting the maximum gas pressure
2 turn the protective hood ”A” counter---clocwise and remove it
from the calibration system. Use a flat---edge screw driver to
help removal;
A
3 rotate adjustment control ”B” to adjust the maximum gas pres-
sure to the prescribed value. Rotate the control clockwise to in-
crease the pressure.
Setting the minimum gas pressure
4 Turn off the electrical supply;
5 remove the connector ”C” to the gas modulator and make it
safe;
6 turn on the electrical supply;
7 rotateadjustmentcontrol”D”toadjust totheminimumpressure
prescribed value. Rotating the control clockwise increases the
pressure;
8 make sure that both minimumand maximumgas pressures are
correctly set by disconnecting and re---connecting the con-
nector ”C” to the gas modulator;
9 close the domestic hot water cock;
10 installthe protectivehoodoverthecalibrationsystemonthe gas
moulator;
11 securely close the gas pressure test point
12 close the appliance.
6.6 Reducing the maximum output to meet
the central heating power requirements
B C
D
1 Ensure electricity is switched off at main isolator;
2 turn the function switch as indicated;
rev. 17.09.93
25
Page 28
Servicing instructions
.
Btu/h
k
W
3 turnthe c.h. temperature adjustmentto itsmaximumpositionas
indicated;
4 remove the service access doors (sect. 6.2);
Do not change position of knobs during operations.
5 lower the control panel (sect. 6.2)
6 removethescrewonthepressure test pointformeasuringoutlet
pressure at the gas valve and fit a pressure gauge using a hose
(step 2 at page 19);
7 switch on the main isolator;
8 using a screwdriver, gently adjust the regulation potentiometer
on the electronic regulation p.c.b. for desired pressure;
rotating the potentiometer counter---clockwise reduces the
maximum current fed tothe gas moulator and thus reduces the
maximum gas pressure to the burner.
9 refer to the diagram shown here to determine pressure for the
heating output you need;
10 securely close the gas pressure test point.
11 close the appliance;
78 491
71 666
64 841
58 015
51 190
44 365
37 539
30 714
23 889
23
21
19
17
15
13
11
9
7
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0
0,4 0,8 1,2 1,6 2,0 2,4 2,8 3,2 3,6 4,00
mbar
ins.w.g
6.7 Electronic regulation p.c.b.
1 Ensureelectricityisswitched offat mainisolatorandremovethe
service access door (sect. 6.2);
2 disconnect the wires from the main terminal board ”A”.
3 disconnect the connectors ”B”;
4 loosenthe screws ”C” which hold the circuit board on the con-
trol panel;
5 remove the electronic regulation circuit board;
6 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.8 Full sequence control p.c.b.
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 remove the screws ”A”;
4 remove the cover on the full sequence control p.c.b. compart-
ment;
C
C
B B B
A
C
C
A
A
A
A
26
rev. 17.09.93
Page 29
Servicing instructions
5 disconnect the electrical connectors ”B”;
6 removethescrew”C ” whichholdtheelectronicregulationp.c.b;
7 remove the circuit board;
8 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.9 Overheat thermostat
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and the right panel of the case; openthe
sealed chamber (sect. 6.2);
3 remove the spring indicated that holds the overheat thermostat
probe;
4 remove the probe downward;
B
B
C
B
B
5 lower the control panel (sect. 6.2);
6 remove the cover on the full sequence control p.c.b. compart-
ment;
7 disconnect the electrical connectors ”A”;
8 remove the protective cap on the overheat thermostat and re-
move the nut ”B” (front view of the control panel);
9 remove the overheat thermostat;
10 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.10 Burner
1 Ensure electricity is switched off at main isolator;
2 remove the front panel, the right panel, the sealed chamber
cover and remove the combustion chamber cover (sect. 6.2);
3 disconnect the wires ”A” from the ignition and detection elec-
trodes;
4 remove the four screws placed at the right and left sides of the
burner;
5 remove the burner;
6 reassemble in reverse order.
A A
B
A
A
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Servicing instructions
6.11 Injectors
1 Remove the burner (sect. 6.10);
2 unscrew injectors;
3 reassemble in reverse order.
Removing injectors, metallic gaskets must be replaced.
6.12 Ignition and/or detection electrodes
1 Remove the burner (sect. 6.10);
2 unscrew the screws ”A” and remove the electrodes;
3 reassemble in reverse order.
6.13 Insulation panels
To replace the front insulation panel
1 Remove the front panel, the right panel, the sealed chamber
cover and remove the combustion chamber cover (sect. 6.2);
2 replace the combustion chamber cover with the insulation
panel.
A A
To replace the side insulation panels
1 Remove the front panel, the right panel, the sealed chamber
cover and remove the combustion chamber cover (sect. 6.2);
2 disconnectthe wires from the ignitionanddetection electrodes;
3 remove the grid sliding it toward the front of the appliance;
4 remove the main heat exchanger (sect. 6.20);
5 remove the screws ”A” (the two at the right hand indicated)
which hold the insulation panel supports to the frame and re-
move the supports;
6 replace the insulation panels;
7 reassemble in reverse order.
To replace the back insulation panel
1 Remove the front panel, the right panel, the sealed chamber
cover and remove the combustion chamber cover (sect. 6.2);
2 remove the burner (sect. 6.10);
3 remove the main heat exchanger (sect. 6.20);
4 estract the spring ”B” downwards;
5 remove the insulation panel;
6 reassemble in reverse order.
A
A
B
6.14 Gas modulator cartridge
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 turn the protection cap ”A” and remove it from the adjustment
control. Use a flat---edge screw driver to help removal;
28
rev. 17.09.93
A
Page 31
Servicing instructions
4 with a 14 mm spanner turn the cartridge ”B”counter-clockwise;
5 remove the cartridge;
6 reassemble in reverse order.
6.15 On---off operator coils
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
To remove the upper operator coil
3 loosen the screw ”A” and remove the connector ”B”;
4 unscrew the screws ”C ” (the right one indicated) and slide the
coil from the valve.
5 reassemble in reverse order.
To remove the lower operator coil
6 Remove the connector ”D”;
7 unscrew the screws ”E” (the right one indicated) and slide the
coil with its housing from the valve.
8 slide the coil from ist housing;
9 reassemble in reverse order.
B
B
A
C
D
E
6.16 Gas modulator coil
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 remove the gas modulator cartridge as explained in sect. 6.14;
4 slide the coil ”A” and its housing from the valve;
5 remove the plate ”B”;
6 slide the coil from its housing;
7 reassemble in reverse order.
A
B
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29
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Servicing instructions
6.17 Gas valve
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 remove the connectors ”A” to the gas modulator;
4 loosethe screw ”B” and remove the connectors”C” and ”D” to
the on---off operators;
5 completelyunscrew the 7 grub---screws ”E”and the hexagonal
headscrew ”F”which jointhe gas valveto the flanges of the gas
inlet and exit pipes;
6 remove the gas valve toward the front;
7 reassemble in reverse order.
6.18 Fan and venturi device
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and the right panel of the case; openthe
sealed chamber (sect. 6.2);
3 removetheconnectingtubes”A”(tothefluegas samplingpoint)
and ”B” (to the air pressure switch);
4 disconnect the connectors ”C”;
5 remove the four screws ”D” which hold the fan to the hood;
6 remove the fan by carrying it downwards.
The venturi device will descend along with the fan. Pull the
venturi device in order to remove it from the fan.
7 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
A
A
E F
E
D
E
B
D
C
B
D
D
C
C
D
A
Re--assembling the venturi device
1 Upside down the venturi device and insert the O---ring in the
groove of the device;
2 hold the fanwith its outlet downwards and insert the venturi de-
vice untillthe O---ring is pressed between the fan outlet and the
device;
3 turn the venturi device as shown;
4 fitthecilindricalgasket ”E”ontheventuridevice sothatthelower
side of the gasket leans on the upper step ”F” of the venturi de-
vice.
30
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E
F
Page 33
Servicing instructions
6.19 Air pressure switch
1 Ensure electricity is switched off at main isolator;
2 loosenthe three screws ”A”and openthe box whichhouses the
air pressure switch; this box is located on the upper left---hand
side of the appliance;
3 disconnect the electrical connectors ”B”;
4 remove the connecting tube ”C” which leads to the venturi de-
vice;
5 remove the air pressure switch;
6 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.20 Main heat exchanger
A
A
A
B
C
7 Ensure electricity is switched off at main isolator;
8 removethe front panel and the right panel of the case, open the
sealed chamber and the combustion chamber (sect. 6.2);
9 drain the main circuit (sect. 6.3);
10 unscrew the connections ”A” on the inlet and outlet pipes;
11 remove the exchanger by pulling it toward the front of the
appliance;
12 reassemble in reverse order.
6.21 Main circuit temperature probe
1 Ensure electricity is switched off at main isolator;
2 removethefrontpanelandtherightpanelofthecase(sect. 6.2);
3 drain the main circuit of the boiler (sect. 6.3);
4 slide the rubber hood (not shown) which protects the probe;
5 remove the connector indicated;
6 unscrew main circuit temperature probe from its pipe;
7 remove it;
8 reassemble in reverse order.
6.22 Pump
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and theright panelof thecase and lower
the control panel (sect. 6.2);
3 drain the main circuit of the boiler (sect. 6.3);
4 open cover ”A” which protects the electrical terminals and dis-
connectthe electrical power cablesandthe earthcablefromthe
pump;
5 remove the four screws indicated with a circle which attach the
pump to the volute (scroll);
6 remove the pump.
A
A
2 3
14
A
rev. 17.09.93
31
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Servicing instructions
Re--assembling the pump
1 Carefully clean the supporting seat for the flat gasket;
2 correctly position the gasket in the seat on the volute (scroll);
3 correctly position the pump and the mounting flange;
4 insert the four mounting screws;
5 tighten the four screws until they meet resistance but do not
allow the screws to exert any uneven pressure whatsoever on
the flange;
6 tighten down the four mounting screws completely in the se-
quence shown in the figure.
Do not overtighten screws;
7 connect the electrical power cables to the pump.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.23 Main circuit flow switch
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and theright panelof thecase and lower
the control panel (sect. 6.2);
3 drain the main circuit (sect. 6.3);
4 completely loosen the two screws ”A”;
5 remove the cover ”B” which protects the microswitch;
6 disconnect the electrical connections;
A
A
B
7 loosen the two screws ”C” which attach the flow switch to the
pipe;
8 remove the flow switch;
9 reassemble in reverse order.
Whenreplacingthe flowswitch, besure topay attention tothe refer-
ence notch on the body of the flow switch; this notch must be lined
up with a similar notch on the pipe.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
6.24 Pump pressure switch
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 drain the main circuit (sect. 6.3);
4 remove the protective cap on the pump pressure switch;
5 disconnect the electrical connections;
6 witha suitableforkspanner unscrew the pump pressureswitch
and remove it;
7 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
C
C
32
rev. 17.09.93
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Servicing instructions
6.25 Temperature---pressure gauge
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and theright panelof thecase and lower
the control panel (sect. 6.2);
3 drain the main circuit (sect. 6.3);
4 withasuitableforkspannerholdtheconnector ”A” andunscrew
the nut ”B” removing the pressure gauge pipe;
5 remove thermometer bulb ”C” from the outlet pipe on the main
heat exchanger;
6 remove the temperature---pressure gauge from the control
panelbypressing onthe elastic splines”D”whichholdit in posi-
tion;
7 reassemble in reverse order.
C
A
D
B
D
6.26 By---pass
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case and lower the control panel
(sect. 6.2);
3 drain the main circuit (sect. 6.3);
4 remove fork ”A” (back view) which holds the by---pass to the
water deviation body;
5 remove the by---pass from the water deviation body.
The by---pass has a profiledinternal element: when assemblingthe
by---pass, the two flat surfaces must be positioned horizontally.
6.27 Automatic air release valve
1 Ensure electricity is switched off at main isolator;
2 drain the main circuit (sect. 6.3);
3 remove the valve by hand unscrewing it;
4 reassemble in reverse order.
A
6.28 Expansion vessel
1 Ensure electricity is switched off at main isolator;
2 remove the front panel and the left panel of the case and lower
the control panel (sect. 6.2);
3 drain the main circuit (sect. 6.3);
4 completely loosen the lower connector indicated which con-
nects the expansion vessel to the appliance;
rev. 17.09.93
33
Page 36
Servicing instructions
5 remove the upper protection plate by loosening the screw ”A”
which holds the plate to the chassis;
6 remove the screws ”B” and move the box containing the air
pressure switch toward the front of the appliance;
7 remove the upper bolt which attaches the expansion vessel to
the transverse bar on the chassis;
8 remove the expansion vessel from above;
9 reassemble in reverse order.
N.B. --- on a rear flue installation or where the access is limited the
boiler must be removed from the wall.
Checking the expansion vessel pressure
1 Remove the front panel of the case and lower the control panel
(sect. 6.2);
2 removetheplugindicatedandchecktheexpansionvesselpres-
sure
Theexpansionvessel isnormallypressurizedto 0.7bar(10,1 p.s.i.).
B
B
A
6.29 Safety valve
1 drain the main circuit (sect. 6.3);
2 unscrew the connectors ”A” and remove the valve;
3 remove the nipple ”B” from the valve;
4 reassemble in reverse order.
6.30 3---way valve
1 Remove the water unit from the appliance (sect. 6.34);
2 move lever ”A” to the ”manual” position;
3 completelyloosenthe screw ”B”and removethe cover from the
3---way valve;
A B
A
B
4 disconnect the electrical connections (both power and ground
connections);
5 remove the four screws ”C” which hold the valve to the water
deviation body;
6 reassemble in reverse order.
34
rev. 17.09.93
A
C
C
C
C
Page 37
Servicing instructions
6.31 D.h.w. heat exchanger
The d.h.w.heat exchanger may be carried out in two ways, according to the manner in which the appliance is installed:
--- fromthe topifat least 40 cm(15,7 ins)offreespace areavailable
between the appliance and any obstacle above the appliance;
--- toward the side (right---hand side) if at least 13 cm (5,1 ins) of
free space are available between the appliance and any obstacle to the right side.
1 Ensure electricity is switched off at main isolator;
2 removethe front paneland the right panel of the case, lowerthe
control panel and the sealed chamber (sect. 6.2);
3 drain the main and d.h.w circuits (sects. 6.3 and 6.4);
4 remove the upper protection plate by loosening the screw ”A”
which holds the plate to the chassis;
5 remove the upper bracket by loosening the screw ”B” which
holds the bracket to the chassis;
A
6 disconnect the d.h.w. outlet ”C”;
7 disconnect the water inlet connector ”D”;
8 remove the collars which join the heat exchanger to the water
deviation body by completely loosening the screws”E”;
9 remove the exchanger;
10 ensure the internal conveyor is lifted clear off the water deviator
and retrieve the O---ring;
11 reassemble in reverse order.
When replacingthe d.h.w.heat exchanger,be sure to pay attention
tothe reference notchon thelower edge of theexchanger shell;this
notch must be lined up with a similar notch on the water deviation
body.
Care should be taken to ensure thatthe O---ring remains in position
when reassembling.
B
C
D
E
E
rev. 17.09.93
35
Page 38
Servicing instructions
Removing the plug
1 Remove the d.h.w. heat exchanger;
2 slacken the automatic air release valve
3 remove the fork;
4 use a screwdriver to pry between the shell and the air release
valve at a number of different points;
5 lift the plug and the valve upwards.
Installing the plug
1 Install O---rings ”A” and ”B” on the grooves in the plug;
2 install O---ring ”C” into the upper flaring of the bellows;
3 insert the plug by rotating it until the fork can be installed;
4 insert the fork ”D”.
To reassemble correctly the O---rings look at the diagram in sect.
6.35 at the end of this chapter.
Automaticair release
valve
fork
shell
D
A
B
C
Disassembling the d.h.w. heat exchanger
1 Remove the d.h.w. heat exchanger from the appliance;
2 remove the internal conveyor ”A”;
3 remove the plug as previously explained;
4 remove the O---rings from the plug;
5 use the plug to push the bellows from the bottom of the shell;
A
36
rev. 17.09.93
Page 39
Servicing instructions
Re--assembling the d.h.w. heat exchanger
1 Position the O---ring gaskets on the lower end of the bellows;
2 insert the bellows into the shell and use the plug, without O---
rings, to force the bellows into its final position;
3 install the plug as previously explained;
4 install the internal conveyor with the conical edge toward the
bottom of the shell.
To reassemble correctly the O---rings look at the diagram in sect.
6.35 at the end of this chapter.
Important
Avoiddeformationofthebellowstoassurepropersealingbythe O--ring gaskets.
Assemblingthed.h.w.exchangerinthe appliancethe lower O---ring
must remain on the edge of the bellows.
6.32 D.h.w. temperature probe
1 Ensure electricity is switched off at main isolator;
2 drain the d.h.w circuit (sect 6.4);
3 remove the upper protection plate by loosening the screw ”A”
which holds the plate to the chassis;
A
4 remove the rubber hood (not shown) whichprotects the probe;
5 disconnect the electrical cables from the d.h.w. temperature
probe ”B”;
6 unscrew d.h.w. temperature probe from its pipe;
7 remove it;
8 reassemble in reverse order.
6.33 D.h.w. flow switch
Two types of basic maintenance are prescribed for this flow switch:
--- Cleaning of the filter and/or insertion of the flow limiter;
--- Complete substitution of the flow switch.
Cleaning of the filter
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case, the lower protection plate
and lower the control panel (sect. 6.2);
3 drain the d.h.w circuit (sect 6.4);
4 completely loosen the inlet connector to the d.h.w. circuit;
5 remove the pipe support spline by loosening the screw ”A”
which holds the spline to the bracket;
6 remove the lower fork ”B” on the flow switch;
7 remove inlet pipe ”C” by gently pulling it downwards;
8 reassemble in reverse order.
When re---assembling this unit, make sure that flow limiter is in-
stalled as shown.
rev. 17.09.93
B
B
A
C
37
Page 40
Servicing instructions
Complete substitution of the flow switch
1 Ensure electricity is switched off at main isolator;
2 remove the front panel of the case, the lower protection plate
and lower the control panel (sect. 6.2);
3 drain the d.h.w circuit (sect 6.4);
4 remove the connectors ”A”;
5 completely loosen the inlet connector for the d.h.w. circuit;
6 remove the pipe support spline by loosening the screw ”B”
which holds the spline to the bracket;
7 completely loosen the connector which connects the flow
switch to the d.h.w. heat exchanger;
8 remove the screws ”C ” that hold the flow switch to the bracket;
9 remove the d.h.w. flow switch;
10 reassemble in reverse order.
A
A
B
CC
6.34 Water unit
The water unit is is an assembly of components which can be removed from the appliance as a single unit.
The unit is made up of the pump, volute (scroll), water deviation
body, heating water filter, 3---way valve, by---pass, d.h.w flow switch
and the heating water flow and return pipes.
1 Ensure electricity is switched off at main isolator;
2 removethe front panel and the right panel of the case; openthe
sealed chamber; remove the lower protection plate and lower
the control panel (sect. 6.2);
3 remove the d.h.w. heat exchanger as explained in sect. 6.31;
4 remove connection collar ”A” on the outlet from the volute
(scroll);
A
5 loosen the connector on the expansion vessel ”B”
6 remove the fork which holds the pipe to the water unit and re-
move the pipe;
38
rev. 17.09.93
B
Page 41
Servicing instructions
7 loosen the outlet connector of the main heat exchanger;
8 remove fork ”C ” which holds the connecting pipe to the main
heat exchanger and move the pipe away from the water deviation body;
9 disconnect the pressure gauge connecting pipe by removing
the fork ”D” which attaches the pipe to the volute (scroll);
10 remove the cable ties;
11 slide the rubber hoods and disconnect the electric connector
”E”;
12 disconnect the connectors on the d.h.w. flow switch and slide
the cable away from the water unit;
D
C
E
13 removetheprotectivecaponthepumppressureswitch anddis-
connect it;
14 completely loosen the three connectors ”F” (c.h. return, c.h.
flow, d.h.w. inlet);
15 removethe twoscrews ”G”whichattach thesupport bracket for
the water unit to the chassis;
16 keep the cables away from the unit and gentlylift the water unit
to release it from the chassis;
17 remove the water unit downwards;
18 reassemble in reverse order.
Toreassemblecorrectlytheelectricwiresandconnectorslookatthe
wiringdiagraminsect.8.1 oratthe diagramstuckonthe innercover
of the control panel.
G
G
F F F
rev. 17.09.93
39
Page 42
Servicing instructions
6.35 O---rings position on the d.h.w. heat exchanger
Plug
Bellows
All O---rings are illustrated in real size
40
rev. 17.09.93
Page 43
7 FAULT FINDING
7.1 Fault finding diagrams
The fault finding diagrams illustrate the proper steps to
be followed when searching for the cause of improper
operation.
Even though the diagrams refer to four specific cases,
theycan be used todiagnose mostcauses ofimproper
operation.
The functions carried out by all components in the
appliance are illustrated; this method of component illustration allows most cases of improper operation to
be corrected.
However, a malfunction may occur which cannot be
troubleshootedfromthe diagrams. Inthiscaseseesection 7.3 and the paragraphs which follow it.
7.2 Using the fault finding diagrams
Each diagram is developed on two sides: a flow chart
of the operating logicof the appliance is printed on the
left, while additional details concerning the flow chart
are printed on the right.
The questions which follow the start point (located insidea rhomb) mustbe answeredbyYESor NOaccordinga test carriedout onthe appliance. Each YES orNO
answer leads to a specific path in the fault finding process, and each path eventually reaches a list of probable causes for the malfunction.
7.3 Special defects
The following types of defects are not indicated on the
fault finding diagrams; each of these problems is
treated in its own section:
--- water leaks;
--- difficulty in lighting gas;
--- incorrect combustion;
--- traces of gas or exhaust gases in the installationarea.
7.4 Water leaks
Leaks from connectors, O--rings or gaskets
Make sure that the surfaces which come into contact
with the gaskets are free from dirt, roughness or deformation. Then, substitute the gasket (both O---ring and
flat gaskets).
Water leaks from the safety valve
This may be caused by leaks from the d.h.w. over--pressurizing the heating circuit.
Make sure that the main circuit pressure gauge is correctlyreadingtheamountofwaterbeing used.Remove
the d.h.w. heat exchanger and check the bellows for
leaks. If necessary, substitute the safety valve.
If the leak only occurs when the applianceis operating,
empty the main water circuit and check the pressure
applied to the expansion vessel (sect. 6.28).
7.5 Difficulty in lighting the burner
Makesurethatinput andoutputpressureson gasvalve
are set to the correct values.
Also, make sure that no pressure variations are being
caused by a malfunctioning component (defective
pressure reducers or regulator; dirty gas filters; other
gas consuming equipment installed on the same gas
line, etc.).
Make sure that the ignition electrode is positioned correctly.
Make sure that injectors are clean.
7.6 Incorrect combustion
Makesure thatthe gasmodulatorhasbeen setcorrectlyand make sure that the followingelements are clean:
--- burner;
--- combustion chamber;
--- flue system.
Make sure that exhaust flues do not return to the
appliance through the air intake duct. Make sure that
the flue terminal on the exhaust system has been installed in the correct position (see the installation instructions).
If extension elements have been used in the exhaust
duct, make sure that these elements have been inserted correctly.
Please note that the maximum flue length is 3 meters.
7.7 Traces of gas or exhaust flues
Ifgas isdetected in the installationarea, usea soapsolutionoraspecificleak---detectionproducttomake sure
that all the gas connectors in the system are perfectly
sealed. Check for leaks when the appliance is shut
down and during operation.
If exhaust flue is detected in the installation area, make
sure that the exhaust duct has been built to the exact
specificationsprescribed. Also, checkthe exhaustduct
for leaks and make sure that it is clean. Make sure that
all exhaust duct---work conforms to current technical
standards.
rev. 17.09.93
41
Page 44
Fault finding
7.8 Appliance completely shut down
Initial conditions:
--- the function switch is on position
--- the thermostat or timer is calling for heat ref. 1;
--- sufficient gas is being fed to the boiler.
Switch on the main isolator
Start
--- electrical power line is faulty;
--- main switch is faulty or disconnected.
--- The heating circuit is not adequately
filled;
--- fuse F2 has blown ref. 4;
--- bad connection on the connector to
the electronic regulation p.c.b.;
--- is there the link connection for the
pump on the main terminal block?
--- the pump pressure switch is faulty;
--- electronic regulation p.c.b. is faulty.
--- pump is blocked;
--- windings of the pump motor are
open ref. 5;
--- open circuit in one of the cables
ref. 6.
--- flow switch on the main water circuit
is faulty;
--- pump impeller is disconnected;
--- pipes to the flow switch plugged;
--- filter on the heating circuitplugged;
--- by---pass valve blocked.
NO
Is power being supplied to
the electronic regulation
p.c.b.? ref. 2.
NO
NO
NO
Is power being
supplied to the
pump ref. 3
Does the
pump rotate?
Does the flow
switch close on the
main water circuit?
YES
YES
YES
ref. 7.
--- This bridge connection
must be present.
--- Fuse F1 has blown ref. 4;
--- the main circuit temperature probe
is faulty ref. 9;
--- a short circuit is present in the
cables to the the main circuittemperature probe ref. 10;
--- the electronicregulation p.c.b. is
faulty.
--- Bad connection on the electronicregulation p.c.b.;
--- open circuit in one of the cables ref. 6;
--- the electronicregulation p.c.b. is faulty.
42
NO
YES
Does the electronic
regulation p.c.b.
properly demand
heat? ref. 8.
rev. 17.09.93
NO
YES
Is there a bridge
connection between
AC and AP on the
electronicregulation
p.c.b.?
YES
NO
Is power being fed to the
device for the full se-
quence control p.c.b.?
ref. 11
YES
--- See the section on troubleshooting the
full sequence control p.c.b.
Page 45
Fault finding
ohm
ref. 1 Supply voltage should be indicated when the
appliance is started and when the thermostat or timer
is open.
Set the tester to VAC
ref. 7 Disconnect the terminals from the microswitch on the
flow switch and measure the resistance. When the
appliance is switched off the resistance should be infinity;when theapplianceisswitchedonthe resistance
should go to zero ohms. Set tester to ohm.
To avoid electric shockscarefullyinsulate the electric terminals on the cable before this test.
ref. 2 Supply voltage should be indicated when power is
supplied to the electronic regulation p.c.b.
Set the tester to VAC
ref. 3 Supply voltage should be indicated when power is
supplied to the pump.
Set the tester to VAC
ref. 4 A fuse generally blows because of an overload. To lo-
cate the cause, disconnect the components connected to the board and measure their electric resistance; see ref. 5.
Spare fuses areavailableinhousing of the electronicregulation p.c.b.
ref. 5 To check a winding, disconnect the winding from its
circuit and measure the resistancein the winding (set
tester to ohm):
Pump 180 ohm
upper on---off operator 4 000 ohm
lower on---off operator 870 ohm
Fan 100 ohm
3---way valve 1 700 ohm
ref. 8 Supply voltage should be present across these ter-
minals when there is a demand for heat.
Set the tester to VAC
12500
11500
10500
9500
8500
7500
6500
5500
4500
3500
2500
1500
500
20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110
°C
ref. 9 The resistance of the temperature probe depends on
its temperature (18 000 ohm at 10°C).
See the diagram for proper electric resistance at other
temperatures. Set tester to ohm.
ref. 10 Disconnect the cable from the temperature probe to
the electronic regulation p.c.b. at both ends and
measure the resistance between the two wires in the
cable, which should be infinity. Set tester to ohm.
ref. 6 Tocheckthe continuityofacable,disconnectthecable
from its circuit and measure the resistance when the
two ends of the cable are connected. The resistance
should be zero ohms with the tester set to the ohms
function.
Set tester to ohm.
ref. 11 Supply voltage should be indicated when power is
supplied to the full sequence control p.c.b.
Set the tester to VAC
43
rev. 17.09.93
Page 46
Fault finding
7.9 Fault of full sequence control p.c.b.
Start
NO
Does the shut---down
warning light indicate
a shut---down?
YES
proper operation after pressing
Does the air pressure
switch stay in the actuated
position? ref. 14.
NO
--- The full sequence
control p.c.b. is faulty.
YES
--- Make sure that there is no condensation in
the pipe to the air pressure switch.
--- The air pressure switch is faulty.
--- Exhaust flues are not exhausted easily and correctly .
--- The tubes to the air switch have been incorrectly
mounted.
--- The pipe to the air pressure switch is plugged.
--- The venturi device is faulty.
--- The air pressure switch is faulty.
supplied to the full sequence control p.c.b?
Does the device resume
the reset microswitch?
YES
Does the fan rotate?
NO
Does the air pressure
switch operate properly
and switch correctly?
Is power being
ref. 12
NO
YES
ref. 18
NOYES
--- There is a bad connection at the connector to the full sequence control p.c.b..
--- open circuit in one of
the cables to the device;
ref. 13.
--- The reset push button is
faulty; ref. 17.
--- An open circuit is present in the cable to the
microswitch; ref. 13.
--- The full sequence control p.c.b. is faulty.
NO
NO
Is power being
supplied to the fan?
ref. 15
YES
--- There is an open circuit in the
windings of the fan motor;
ref. 16.
--- An open circuit is present in
one of the cables; ref. 13.
Does the burner light
for a short time, but
sparking continues and
the appliance then
shuts down?
--- The detection electrode is
faulty.
--- The cable or connector in the
detection circuit is faulty.
--- The full sequence control
p.c.b. is faulty.
Is power being
supplied to the ON---
OFF operators?
ref. 20
NO
Does the burner
partially light and
then the appliance
YES NO
NO
--- The contacts in the overheat thermostat are open; ref. 21.
--- There is a bad connection at the connector to the full sequence control p.c.b.
--- An open circuit is present in one of the cables to the safety
thermostat;ref. 13.
--- The full sequence control p.c.b. is faulty.
shuts down?
NO
YES
Is there proper
sparking at the igni-
tion electrode?
ref. 19
YES
Are the coils intact in
the ON---OFF oper-
ators? ref. 22
NOYESYES
--- Make sure that the correct type of gas is
being fed, and that the gas feed pressure
is correct.
--- Injectors are dirty or plugged.
YES
--- Make sure that gas is being fed to the
appliance.
--- The gas valve is faulty.
--- The ignition electrode is
--- A cable or connector in
--- The full sequence control
--- Substitute the faulty operator.
faulty.
the gas lighter circuitis
faulty.
p.c.b. is faulty.
44
rev. 17.09.93
Page 47
Fault finding
ref. 12 Supply voltage should be indicated when power is
supplied to the device. Set tester to VAC.
ref. 17 Disconnect the connector from the device and
measure the resistance.The tester should indicate
zeroohmswhenthemicroswitchisactuated.Settester
to ohm.
ref. 13 Tocheckthecontinuityofacable,disconnectthecable
from its circuit and measure the resistance when the
two ends of the cable are connected. The resistance
should be zero ohms. Set tester to ohm.
ref. 14 Disconnect the connector from the device and
measure the resistance.If the contacthas remained in
the actuated position, the resistancewillbe zeroohm.
Set tester to ohm.
ref. 15 Supply voltage should be indicated when power is
supplied to the fan motor. Set tester to VAC.
ref. 18 If approx. 16VDC is present across the terminals
shown in the diagram, the air pressure switch is not
switching properly. Set tester to VDC.
ref. 19 The sparks from the lighter must be positioned per-
pendicularto the burner ramp. The distance from the
electrodeto the ramp must be 5 mm.
ref. 20 Supply voltage should be indicated when power is
supplied to the operators. Set tester to VAC with the
device reset from shut---down. Set tester to VAC.
ref. 16 Disconnect the connector from the device and
measure the resistance.If an open circuit is present in
the motor windings or in the cablesto the fan, noindication will appear on the tester. Set tester to ohm.
rev. 17.09.93
ref. 21 Disconnect the connector from the device and
measure the resistance. If the contacts in overheat
thermostat are open no indication will appear on the
tester. Set tester to ohm.
ref. 22 To check the coil in the on---off operators, disconnect
thewindingfromitscircuitand measure theresistance
in the winding (set tester to ohm):
upper on---off operator 4 000 ohm
lower on---off operator 870 ohm
45
Page 48
Fault finding
7.10 Fault on d.h.w. --- c.h. switching
Initial conditions:
--- the function switch is in position.
--- the thermostat or timer is calling for heat ref. 23.
--- The lever on the 3---way valve is set to ”automatic”;
ref. 24.
--- There is a faulty sensor or float in
the flow switch on the d.h.w. circuit. ref. 29
--- The float is jammed.
NO
When d.h.w. is withdrawn, do
the contacts close in the flow
switch?ref. 28
YES
--- The electronic regulation p.c.b. is faulty.
Start
The appliance operates in the
c.h. mode only, and not in the
d.h.w. mode.
When d.h.w. is with-
drawn, does the burner
shut off immediately?
NO
When d.h.w. is with-
drawn, is power fed to
YES
the 3---way valve?
ref. 27
NO
--- The 3---way valve is blocked
in the c.h. mode; ref. 25.
--- Air is present in the d.h.w. heat exchanger.
--- The by---pass valve is faulty.
--- The flow switch on the main circuit
is faulty.
YES
YES
When d.h.w. is withdrawn,
do the contacts open in the
flow switch on the main cir-
cuit? ref. 26
NO
--- The d.h.w. temperature probe is short--circuited.
--- The electronic regulation p.c.b. is faulty.
--- The electronic regulation p.c.b. is faulty.
NO
When d.h.w. is not being
withdrawn, do the contacts
close in the d.h.w. flow
switch?ref. 28
YES
--- There is a faulty sensor or float in the
d.h.w. flow switch ref. 29
Start
Theapplianceoperates inthe
d.h.w.modeanddoesnotoperate in the c.h. mode.
When d.h.w. withdrawal
is terminated, does the
burner immediately
shut off?
NO
When d.h.w. is not being
withdrawn, is power fed to
NO
the 3---way valve? ref. 27
YES
--- The motor in the 3---way valve is faulty, or there is
an open circuit in the cable to the valve. ref. 30
YES
--- The by---pass valve is faulty or
incorrectly calibrated.
--- The main circuit flow switch is
faulty.
YES
When d.h.w. withdrawal is
terminated, do the contacts
open in the main circuit flow
switch?ref. 26
NO
--- The electronic regulation p.c.b. is faulty.
46
rev. 17.09.93
Page 49
Fault finding
ref. 23 Supply voltage should be indicated when the
appliance is started with an open thermostat or timer.
Set the tester to VAC.
ref. 24 The correct position of the lever on the 3---way valve
during normal operation is shown in the picture (the
lever should be positioned toward the right, as seen
from the front of the appliance).
ref. 25 If power is not being supplied to the3---way valve, the
lever must move freely over the first half of its travel
from left to right. Also, the lever must meet resistance
when moved over the remaining half of its travel from
left to right. If the lever moves freely from left to right
over its entire travel, the 3---way valve is jammed or
faulty. Substitute the valve.
ref. 27 Powerisbeingsupplied tothe3---way valve when sup-
plyvoltageis measured acrossthe pointsshowninthe
diagram. Set the tester to VAC.
ref. 28 If 12 VDC is measured across the points shown in the
diagram, the contacts are open in the d.h.w. flow
switch. If 0 volts are measured, the contacts are
closed. Set the tester to VDC.
ref. 29 Disconnect the flow switch on the d.h.w. circuit and
connectan ohmmeterasshownabove. The contactin
the sensor on the flow switch is normally open (resistance at infinity). Withdrawing a sufficient quantity of
d.h.w.the contactmustclose(resistancezero).Setthe
tester to ohm.
ref. 26 When the contactsopeninthemaincircuitflowswitch,
the voltage across the points shown in the diagram
shouldincreasefrom0 volts to supply voltage. Set the
tester to VAC.
rev. 17.09.93
ref. 30 Attheelectronicregulationp.c.b,disconnectthecable
fromthe3---way valve to the board. Measuretheresistance across the cable, which should be 1700 ohm.
Set the tester to ohm.
47
Page 50
Fault finding
7.11 Fault on modulation
Initial conditions:
--- C.h. and d.h.w.temperature adjustments on
maximum position.
--- Low temperature on c.h. and d.h.w.circuits.
Turn the function switch on
Turn the c.h. and d.h.w. temperature adjustments on minimum
position.
Close all radiators except the
smallest one; ref. 33.
YES NO
Start
Is the gas pressure to
the burner at its maxi-
mum value?
ref. 31
--- Inspect the gas installation for
faults and adequate dimensioning.
NO
Does the boiler reduce
the gas pressure to the
burner while the c.h.
temperature rises?
NO
--- The main circuit temperature probe is
faulty; ref. 34.
--- the cable which connects the main circuit
temperature probe to the electronicregulation p.c.b. is faulty; ref. 35.
--- The d.h.w. temperature probe is faulty; ref. 34.
--- the cable which connects the d.h.w. temperature probe
YES
Withdrawn a small quantity (3 to 4 lts/min) of domestic hot water.
Does the boiler reduce
the gas pressure to the
burner while the d.h.w.
temperature rises?
--- No faults on modulation
NO
to the electronic regulation p.c.b. is faulty; ref. 35.
--- The coil of the gas modulator is
faulty; ref. 36.
--- The cartridge of the gas modulator
is faulty.
--- The gas valve is faulty.
YES
YES
Is the inlet pressure to
the boiler adequate?
ref. 32
YES
Is the current flowing
through the gas
modulator coil at its
maximum value?
ref. 37
48
NO
--- The electronic regulation p.c.b. is
faulty.
rev. 17.09.93
Page 51
Fault finding
ohm
ref. 31 Check thegaspressureatthe testpointformeasuring
outletpressureat the gas valve and compare with the
value on sect. 1.2.
ref. 32 Check thegaspressureatthe testpointformeasuring
inlet pressure at the gas valve and compare with the
value on sect. 1.2.
ref. 33 e.g. leave the smallest radiator open and close the
others.
12500
11500
10500
9500
8500
7500
6500
5500
4500
3500
2500
1500
500
20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110
°C
ref. 34 The resistance of the temperature probe depends on
its temperature (18 000 ohm at 10 °C).
See the diagram for proper electric resistance at other
temperatures. Set the tester to ohm.
ref. 36 Tocheck the coil of the gas modulator disconnect the
winding from its circuit and measure the resistance in
the winding (set the tester to ohm):
Gas modulator coil 125 ohm
ref. 35 Tocheckthecontinuityofacable,disconnectthecable
from its circuit and measure the resistance when the
two ends of the cable are connected. The resistance
should be zero ohms with the tester set to the ohms
function. Set the tester to ohm.
ref. 37 To check the current flowing through the gas modu-
lator coil disconnect one of the connectors and insert
theammeter(200mA=full---scaleminimum)between
the connectorand the terminal of the coil.
To obtain the maximum gaspressuretothe burnerthe
current must be at least 150 mA=.
Set the tester to ADC.
rev. 17.09.93
49
Page 52
8 ELECTRIC DIAGRAMS
Y
8.1 General wiring layout
FAN
GAS
VALVE
b
br
g/y
IGNITION
ELECTRODE
b
br
AIR PRESSURE SWITCH BOX
RESET
PUSH
BUTTON
SHUT
DOWN
WARNING
LIGHT
AIR PRESSURE
SWITCH
D.H.W
TEMPERATURE
PROBE
b
br
b
br
w
bk
br
b
bk
DETECTION
bk
ELECTRODE
b
br
b
br
b
b
br
g/y
br
r
bk
g/y
b
br
b
REGULATIONP.C.B.
b
br
bk
br
FULL SEQUENCE
CONTROL P.C.B.
ELECTRONIC
F1 --- 0,08 A T
F2 --- 1,6 A T
MAIN CIRCUIT
TEMPERATURE
PROBE
bk
r
OVERHEAT
THERMOSTAT
b
br
b
br
r
D.H.W.
FLOW
SWITCH
w
bk
w
bk
r
r
g
bk
bk
bk
b
br
MAIN
CIRCUIT
FLOW
SWITCH
r
br
bk
g/y
g/y
g/y
b
b
br
b
b
br
bk
g/y
br
g/y
b
br
PUMP
PRESSURE
b
br
bk
g/y
EXTERNAL CONTROL
TERMINAL BLOCK
TT
TR
TC
SWITCH
b
br
PUMP
L
N
g/y
br
b
g/y
br
b
3 WAY VALVE
MAIN
SUPPL
240 V~
50
rev. 17.09.93
Page 53
Electric diagrams
8.2 Functional flow diagrams
General layout
function switch position: off
F2 (1,6 A T) F1 (0,08 A T)
L N
TB1---L
TB1---P3
J1---4
br
PUMP
PRESSURE SWITCH
S1
FUNCTION SWITCH
b
J1---5
K1 (RELAY)
K2 (RELAY)
TRANSFORMER
L --- LINE N --- NEUTRAL
J1---6
bk b
3 WAY
VALVE
ACTIVATED CIRCUIT
NON ACTIVATED CIRCUIT
21V=
12V=
TO THE LOWVOLTAGE
SECTION OF THE
REGULATIONP.C.B.
J1---3
N
TB1---P2
TB1---P1
TB1---PC
LINK OR ROOM THERMOSTAT
IN ”HEATREQUEST” CONDITION
TC
TR
TT
bk
b
br
TB1---TC
TB1---TR
TB1---TT
PUSH BUTTON
THERMOSTAT
RESET
OVERHEAT
TB1---AC
TB1---AP
SHUT DOWN
WARNING LIGHT
J1---9
J2---2
b
MAIN CIRCUIT
FLOW SWITCH
---
2 16
bk
3 15
b
4 17
br
5 13
bk
6 14
w
br
b
FULL
SEQUENCE
CONTROL
P.C.B
10 11
12
br
J1---10
J1---1
br
PUMP
AIR PRESSURE SWITCH
bk
br
b
b
br
br
com
FAN
GAS VALVE SOLENOIDS
J1---2
b
no
nc
N
N
DETECTION
ELECTRODE
IGNITION
ELECTRODE
18 9
1
CONNECTOR ON THE H.V. TRANSFORMER
rev. 17.09.93
b
J2---1
b
N
51
Page 54
Electric diagrams
Function switch position
Heat request on c.h.
F2 (1,6 A T) F1 (0,08 A T)
L N
TB1---L
TB1---P3
J1---4
br
PUMP
PRESSURE SWITCH
S1
FUNCTION SWITCH
b
J1---5
K1 (RELAY)
K2 (RELAY)
TRANSFORMER
L --- LINE N --- NEUTRAL
J1---6
bk b
3 WAY
VALVE
ACTIVATED CIRCUIT
NON ACTIVATED CIRCUIT
21V=
12V=
TO THE LOWVOLTAGE
SECTION OF THE
REGULATIONP.C.B.
J1---3
N
TB1---P2
TB1---P1
TB1---PC
LINK OR ROOM THERMOSTAT
IN ”HEATREQUEST” CONDITION
TC
TR
TT
bk
b
br
TB1---TC
TB1---TR
TB1---TT
PUSH BUTTON
THERMOSTAT
RESET
OVERHEAT
TB1---AC
TB1---AP
SHUT DOWN
WARNING LIGHT
J1---9
J2---2
b
MAIN CIRCUIT
FLOW SWITCH
---
2 16
bk
3 15
b
4 17
br
5 13
bk
6 14
w
br
b
FULL
SEQUENCE
CONTROL
P.C.B
10 11
12
br
J1---10
J1---1
br
PUMP
AIR PRESSURE SWITCH
bk
br
b
b
br
br
com
FAN
GAS VALVE SOLENOIDS
J1---2
b
no
nc
N
N
DETECTION
ELECTRODE
52
IGNITION
ELECTRODE
18 9
1
CONNECTOR ON THE H.V. TRANSFORMER
rev. 17.09.93
b
J2---1
b
N
Page 55
Electric diagrams
Function switch position
Heat request on d.h.w.
F2 (1,6 A T) F1 (0,08 A T)
L N
TB1---L
TB1---P3
J1---4
br
PUMP
PRESSURE SWITCH
S1
FUNCTION SWITCH
b
J1---5
K1 (RELAY)
K2 (RELAY)
TRANSFORMER
L --- LINE N --- NEUTRAL
J1---6
bk b
3 WAY
VALVE
ACTIVATED CIRCUIT
NON ACTIVATED CIRCUIT
21V=
12V=
TO THE LOWVOLTAGE
SECTION OF THE
REGULATIONP.C.B.
J1---3
N
TB1---P2
TB1---P1
TB1---PC
LINK OR ROOM THERMOSTAT
IN ”HEATREQUEST” CONDITION
TC
TR
TT
bk
b
br
TB1---TC
TB1---TR
TB1---TT
PUSH BUTTON
THERMOSTAT
RESET
OVERHEAT
TB1---AC
TB1---AP
SHUT DOWN
WARNING LIGHT
J1---9
J2---2
b
MAIN CIRCUIT
FLOW SWITCH
---
2 16
bk
3 15
b
4 17
br
5 13
bk
6 14
w
br
b
FULL
SEQUENCE
CONTROL
P.C.B
10 11
12
br
J1---10
J1---1
br
PUMP
AIR PRESSURE SWITCH
bk
br
b
b
br
br
com
FAN
GAS VALVE SOLENOIDS
J1---2
b
no
nc
N
N
DETECTION
ELECTRODE
IGNITION
ELECTRODE
18 9
1
CONNECTOR ON THE H.V. TRANSFORMER
rev. 17.09.93
b
J2---1
b
N
53
Page 56
Electric diagrams
Function switch position
Heat request on d.h.w.
F2 (1,6 A T) F1 (0,08 A T)
L N
TB1---L
TB1---P3
J1---4
br
PUMP
PRESSURE SWITCH
b
S1
FUNCTION SWITCH
J1---5
K1 (RELAY)
K2 (RELAY)
TRANSFORMER
L --- LINE N --- NEUTRAL
J1---6
bk b
3 WAY
VALVE
ACTIVATED CIRCUIT
NON ACTIVATED CIRCUIT
21V=
12V=
TO THE LOWVOLTAGE
SECTION OF THE
REGULATIONP.C.B.
J1---3
N
TB1---P2
TB1---P1
TB1---PC
LINK OR ROOM THERMOSTAT
IN ”HEATREQUEST” CONDITION
TC
TR
TT
bk
b
br
TB1---TC
TB1---TR
TB1---TT
PUSH BUTTON
THERMOSTAT
RESET
OVERHEAT
TB1---AC
TB1---AP
SHUT DOWN
WARNING LIGHT
J1---9
J2---2
b
MAIN CIRCUIT
FLOW SWITCH
---
2 16
bk
3 15
b
4 17
br
5 13
bk
6 14
w
br
b
FULL
SEQUENCE
CONTROL
P.C.B
10 11
12
br
J1---10
J1---1
br
PUMP
AIR PRESSURE SWITCH
bk
br
b
b
br
br
com
FAN
GAS VALVE SOLENOIDS
J1---2
b
no
nc
N
N
DETECTION
ELECTRODE
54
IGNITION
ELECTRODE
18 9
1
CONNECTOR ON THE H.V. TRANSFORMER
rev. 17.09.93
b
J2---1
b
N
Page 57
55
Page 58
9 SHORT SPARE PARTS LIST
Key G.C. part Description Manufacturer’s No. Manuf.
no. no. reference Part No.
1 164080 12 ramps burner 1 KG2004101
2 379102 Injectors (including copper gaskets) Polidoroø 1.35 mm 12 KG2004 106
3 379083 Gas modulator cartridge SIT Control 0.928.850 1 KG2004117
4 379081 Gas valve SIT Control 827 Nova 0.827.150 1 KG2004 113
5 379097 Expansion vessel (including gasket) 1 KG2003136
6 164006 D.h.w. bellows (including O---rings) 1 KG2001108
7 164079 Main heat exchanger (including gaskets) 1 KG2003157
8 Fan 1
9 379091 Air pressure switch Yamatake---Honeywell C6065A1010 1 KG2027 101
10 164 163 Front combustion chamber insulation panel 1 KG2017106
11 164 166 Side combustion chamber insulation panel 1 KG2017109
12 164 159 Rear combustion chamber insulation panel 1 KG2017101
13 386 714 D.h.w.expansion vessel (optional) 1 KG2001130
14 379 085 Safety valve (including gaskets) Caleffi 512 1/2” 1 KG2005 108
15 164 056 Pump (including gasket) 1 KG2002132
16 379 092 3 way valve (including shutter and O---ring) MUT SF20 (without deviation body) 1 KG2002103
17 164 074 Main circuit flow switch 1 KG2003152
18 164 011 D.h.w.flow switch (complete) 1 KG2001113
19 164 126 Electronic regulation p.c.b. 1 KG2006122
20 164 112 Full sequence control p.c.b. 1 KG2006106
21 379 080 Pump pressure switch CEME 1 KG2002 129
22 379 086 Overheat thermostat FIRT STB/901 1 KG2006 112
23 164 119 Fuse 0,08 A T (F1) 1 KG2006115
24 164 120 Fuse 1,6 A T (F2) 1 KG2006116
25 164 026 D.h.w.temperature probe (including gasket) 1 KG2001 128
26 164 026 Main circuit temp. probe (including gasket) 1 KG2001 128
27 379 079 Automatic air release valve (including O---ring) Caleffi ”robocal” 5030 3/8” GAS 502630 1 KG2001101
28 164 081 Ignition electrode 1 KG2004102
29 164 081 detection electrode 1 KG2004102
30 379 088 Shut down warning light 1 KG2006128
31 379 087 Reset push button 1 KG2006111
32 164 117 Temperature---pressure gauge (including gasket) 1 KG2006113
33 164 210 Flat gasket pack (complete) 1 KG2009101
34 164 211 O---ring pack (complete) 1 KG2009102
56
rev. 17.09.93
Page 59
Short spare parts list
1 2 3 4
7 8 9
10 11 12 13 14
5 6
15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34
rev. 17.09.93
57boiler 20/1 MFS
Page 60
Cod: 17962.0169.0 9410
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