Immergas EOLO Star 23 kW Guide

EOLO Star 23 kW
Instantaneous wall-hung
with room-sealed boilers
EOLO Star 23 kW
S.C FUTURE LINE INSTAL S.R.L
str. Biharia nr.67-77, sector 1, Bucuresti, ROMANIA
serviceimmergas.ro
Dispecerat Non Stop
Tel. Fix : 021-201.11.14
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STESkW ed 05/06 EOLO Star 23 kW
Technical Documentation Technical Documentation
EOLO Star 23 kW
Compact instantaneous wall-hung room-sealed
(type C) fan-assisted boiler.
EOLO Star 23 kW
EOLO Star 23 kW is a wall-hung, room-sealed fan-assisted
boiler for heating and production domestic hot water.
is very compact boiler (H=785 mm, W=450 mm, D=250
mm), has an output heat of 23.3 kW (20,000 kcal/h).
A microprocessor controlled electronic board adjusts and
controls the appliance (burner ignition, temperature adjust-
ment, flame modulation and diagnostics) and, by means of a
digital interface with display and push buttons, the operating
parameters can be displayed and set.
General features.
e hydraulic circuit is equipped with a copper bithermal type
water-gas exchanger for the production of hot water for central
heating and domestic use, an automatic by-pass on the system
and a flow switch for tapping the domestic hot water.
Combustion air intake inside the sealed chamber and the
expulsion of gases are ensured by a fan. A differential pressure
switch controls correct operation.
Legend:
G - Gas supply
AC - Hot water outlet
AF - Cold water inlet
R - System return
M - System delivery
V - Electrical supply
Main dimensions and main connections.
Height (mm) Width (mm) Depth (mm)
785 450 250
CONNECTIONS
GAS
DOMESTIC
CIRCUIT
WATER
SYSTEM
G AC AF R M
3/4” 1/2” 1/2” 3/4” 3/4”
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Legend:
1 - Testing hole (A air) – (F flue)
2 - Sealed chamber
3 - Fan
4 - Combustion chamber
5 - D.h.w. flow switch
6 - Gas valve
7 - D.h.w. probe
8 - Filling valve
9 - Pressure point, positive signal
10 - Pressure point, negative signal
11 - Flue pressure switch
12 - Delivery probe
13 - Safety thermostat
14 - System expansion vessel
15 - Automatic air vent
Main components.
16 - Boiler circulator
17 - System pressure switch
18 - Manifold
19 - 3 bar safety valve
20 - Boiler pressure gauge
21 - System draining cock
22 - Draught diverter
23 - Rapid heat exchanger
24 - Ignition/detection electrodes
25 - Burner
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Legend:
1 - Reset Push Button
2 - Stand-by / Summer / Winter Push Button
3 - Push button (+) to increase d.h.w. temperature
4 - Push button (-) to reduce d.h.w. temperature
5 - Push button (+) to increase system water temperature
6 - Push button (-) to reduce system water temperature
7 - Boiler pressure gauge
8 - D.h.w. functioning mode
Control panel.
9 - Displays temperatures and error codes
10 - Unit of measure
11 - Central heating functioning mode
12 - Winter
13 - Summer
14 - Power supplied
15 - Burner operating
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e central heating circuit, with relevant control and safety
devices, is operated every time a central heating request is
made.
Operation.
e heat contained in the fumes produced by combustion
is absorbed by the copper blades of the water-gas exchanger
(7) which, in turn, transfers it to the water circulating inside
thanks to the boiler circulator (16).
e hot water is then transferred directly into the central heat-
ing system through the delivery (M) and return (R) pipes.
Legend:
1 - D.h.w. probe
2 - D.h.w. flow switch
3 - Gas valve
4 - Flow limiter
5 - Draining cock
6 - Burner
7 - Rapid exchanger
8 - Fan
9 - Sealed chamber
10 - Flue pressure switch
11 - Draught diverter
12 - System expansion vessel
13 - Delivery probe
14 - Safety thermostat
15 - Automatic air vent
16 - Boiler circulator
17 - System pressure switch
18 - Automatic by-pass
19 - 3 bar safety valve
20 - Filling valve
G - Gas supply
AC - D.h.w. outlet
AF - Cold water inlet
R - System return
M - System delivery
Hydraulic circuit.
Primary circuit (Boiler Circuit).
Hot water for central heating and domestic use is produced
by two separate circuits that work as required.
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Boiler circulator (1).
e pump works on the primary circuit return and is located
on the brass manifold assembly.
It is connected to the enbloc and primary exchanger by means
of threaded fittings.
e automatic valve vent is housed on the body (2).
Primary exchanger.
is is a water-gas bithermal type blade exchanger with pipes
and fins in copper for the production of hot water for central
heating and domestic use.
(until serial number 3078554) number of fins = 79.
(from serial number 3078555) number of fins = 86.
It therefore works directly on both circuits to which it is con-
nected by pipes with threaded fittings (3) with a flat gasket
seal (4).
e 6 oval pipes it consists of, inside which flows the water of
the central heating circuit, contain an equal number of “cross-
shaped” pipes for the direct transit of domestic hot water (see
illustration below).
ese pipes are plumbed in parallel in groups of three on the
central heating circuit and in series on the d.h.w. circuit.
e overheating safety thermostat (2) is fixed on the side of
the exchanger exit with a fork (1).
e relevant NTC delivery probe is screwed into place on the
central heating delivery pipe (5).
Head flow rate graph.
e available head the appliance is able to guarantee to the
system in the central heating mode depends on the flow rate
which is shown in the following graph where we can see the
characteristic curve with the pump working at second and
top speed.
Head (m H2O)
A = Head available to the system at third speed
B = Head available to the system at second speed
Head (kPa)
A
2
1
Domestic
cold
water
inlet Domestic
hot
water
outlet
Domestic
hot
water
outlet System
delivery
System
return
Exchanger pipe section
System
central
heating circuit
D.h.w.
circuit
B
Flow rate (l/h)
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Safety devices and controls.
Automatic system by-pass (4).
is device ensures circulation in the central heating circuit
even when this is prevented by the system’s high resistance.
It works between the delivery and return of the central heating
circuit and is accessible after having unscrewed the cap (5) on
the brass manifold’s hook (1).
System water pressure switch (7).
is is an absolute pressure switch that reads the pressure inside
the central heating circuit.
It is housed in the manifold (1) and coupled to a microswitch
that prevents the boiler working when the pressure measured
is below 0.3 bar.
is prevents the bithermal exchanger from overheating.
Filling valve (3).
is valve is between the boiler circuit and the domestic cold
water inlet and permits pressurisation of the central heating
system.
It is located underneath the brass manifold (1) to which it is
screwed.
3-bar safety valve (2).
is valve prevents the safety pressure being exceeded in the
circuit (3 bar).
It is on the front of the manifold (1), secured to it on the side
with an Allen screw.
When this valve triggers, water exits from the boiler return
pipe.
Automatic air vent (8).
It automatically expels any gaseous substances from the cir-
cuit.
It is mounted on the pump’s delivery side.
Expansion vessel (9).
It compensates for variations in volume as a result of heating
the water which also limits pressure variations.
It has a 6-litre capacity (3.95 useful litres) and a pre-load pres-
sure of 1.0 bar.
It is located on the right of the boiler alongside the sealed
chamber and is connected to the return manifold (1) by a
copper pipe (6) with threaded fittings.
8
9
6
7
4
5
1
2
3
6
Central
heating
exchanger
delivery
Pump
return
System
delivery
System
return
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Secondary circuit (D.h.w. circuit).
Operation.
When domestic hot water is drawn, cold water flows inside
the flow switch (4) which closes the electrical contact coupled
to it (see the electrical circuit).
As a result, the adjustment circuit starts the d.h.w. priority
phase that ignites the burner (3) and, if there is an ongoing
central heating request, switches the boiler circulator off.
In this way, the heat in the fumes produced by combustion is
absorbed by the copper blades of the bithermal exchanger (2)
and transferred to the heating circuit water which, in turn,
transfers it to the domestic water circuit flowing through the
“cross-shaped” hot water circuit pipes (1).
D.h.w. flow switch.
Whenever hot water is drawn at a rate of at least 1.5 l/min and
with a dynamic pressure of 0.3 bar, the flow switch (2) enables
the boiler to operate in the d.h.w. mode.
is is done by means of a magnet that, by lifting when hit by
the flow of cold water, moves near to an electrical contact (reed
relay) causing it to move thanks to the effect of the magnet.
When the contact closes, which is located outside the pipe
through which the water flows, it enables the modulation board
to start the domestic hot water priority operating mode.
It consists of two blocks (one in brass and one in plastic) that
are coupled together and locked with a pin (3).
An 8.0 l/min (2 bar) flow limiter (1) is installed at the flow
switch exit.
Bithermal exchanger
(see the central heating circuit).
Note: to ensure long life and have an exchanger that is always
efficient, we recommend installing the “polyphosphates dispenser
kit” if the water is likely to lead to scale forming. For example,
this kit is recommended when the hardness of the water exceeds
25 French degrees.
1
2
3
Cold domestic
water inlet
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Technical DocumentationTechnical Documentation
e circuit consists of an atmospheric burner and a modu-
lating gas valve for gas combustion and flow adjustment
respectively.
Operation.
When the main coils are energised (3) both the inner valve
shutters open allowing gas to flow towards the burner.
e flow rate/outlet pressure is set by means of the gas valve
stabiliser and the modulation coil (1).
By mean of the burner nozzles (7) fuel is injected into the Ven-
turi tubes (ramps) inside which the air-gas mixture is obtained
that is ignited by the spark from the ignition electrode (5).
Modulating gas valve.
e gas valve (SIT 845) features two main coils (3) and a
modulation coil (1) controlled by the integrated board.
e maximum and minimum outlet pressure can be set with
this valve (see gas settings).
Main electric coils (3).
ey are two ON-OFF type coils supplied (230 Vac) by the
integrated board when the burner has to be ignited.
ey are electrically connected in parallel and supplied by
mains power through a special connector (2).
Modulation coil (1).
is is a low voltage coil controlled by the integrated board.
It controls the gas valve stabiliser and permits changing of
the outlet pressure in a way proportionate to the DC running
through it.
Gas circuit.
Burner.
e burner consists of 12 horizontal Venturi tubes (6) inside
which the gas is injected by an equal number of nozzles (7)
mounted on the specific manifold (8) and whose diameter
varies according to the type of gas used (see technical data).
Ignition occurs by means of an integrated p.c.b. that controls
the ignition (5) and detection (4) electrodes.
Ignition electrode (5).
is is controlled by the integrated board that produces an
electrical charge between its end and the burner surface which
is responsible for igniting the air-gas mix.
is electrode is at the front of the burner in line with the
centre ramp.
Detection electrode (4).
is is controlled by the integrated board and detects burner
ignition.
It is positioned at the front of the burner on the same ramp
as the ignition electrode.
1
3
2
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Gas settings.
Maximum and minimum gas pressure settings are done by
means of the gas valve, respecting the values shown in the
tables relating to each appliance for the relevant type of gas
(see technical data).
e features of this appliance are such as to make it possible to
differ minimum pressure settings during operation in both
the central heating and domestic hot water modes.
e minimum gas pressure setting on the gas valve does in fact
correspond to the minimum pressure in the d.h.w. phase
(7.0 kW = 6,000 kcal/h) while, with regard to heating, the
minimum pressure (9.3 kW = 8,000 kcal/h) can be adjusted
by means of the “Minimum central heating power” param-
eter programmable on the integrated printed control board (see
Legend:
1 - Coil
2 - Minimum power adjustment screw
3 - Maximum power adjustment nut
4 - Gas valve outlet pressure point
5 - Gas valve inlet pressure point
6 - Protection cap
SIT 845 valve
integrated board programming).
A differential pressure gauge is used for reading the pressure: its
positive pressure point is connected to the gas valve (4) outlet
and its negative pressure point is connected to the positive
pressure point on the flange with holes located at the top of
the sealed chamber (see figure).
Gas valve SIT 845.
Setting maximum pressure.
Draw some domestic hot water after having put its temperature
selector on maximum.
Turn the brass nut (3) clockwise to increase pressure and in
the opposite direction to reduce it.
Setting minimum pressure.
(to be done after setting maximum pressure).
After turning power off to the modulation coil, turn the screw
(2) clockwise to increase pressure to the burner and in the op-
posite direction to reduce it.
Converting gas type.
Adaptation to a type of gas different to the standard one the
boilers are intended for can be done by using the special kits
(natural gas or LPG).
Conversion consists in replacing the burner nozzles and
modifying the “P1” parameter programmable on the integrated
p.c.b. (see integrated board programming).
Maximum and minimum d.h.w. pressures are then set on the
gas valve in the way described above.
Maximum and minimum power in the central heating mode
can be set by means of parameters (see integrated board opera-
tion).
Burner ignition pressure is not set because the type of board
operation does not require this type of setting (see integrated
board operation).
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Flue circuit.
Operation.
e products of combustion, after hitting the water-gas ex-
changer (1) are conveyed to a hood (2) on top of which the
fumes extractor (3) is fitted (fan).
Fan operation ensures the forced expulsion of the fumes and,
at the same time, creates a vacuum in the sealed chamber (6)
so the combustion air can be aspirated from outside.
Correct fume extraction is controlled by a differential fumes
pressure switch (5); when it trips it either enables or prevents
burner ignition.
Air/fumes testing holes (7-8).
On the top of the outside of the sealed chamber are two holes
with screw closing. ey are accessible from the front and are
used to sample combustion air (7) and fumes (8).
Signal pressure points, flue pressure switch (9-
10).
On the top of the outside of the sealed chamber are two
pressure points with screw closing. By means of these points
the signal at the ends of the flue pressure switch (5) can be
measured.
(until serial number 3078554)
e negative pressure point (9) is coupled to a Y-shaped pipe
(11) that, in turn, is connected to the negative pressure point
of the flue pressure switch (5) and to the pressure point at
the outlet of the Venturi tube fitted at the end of the fan
exhaust.
e positive pressure point (10) is connected directly to the
inside of the sealed chamber.
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(from serial number 3078555)
e negative pressure point (9) is connected to a Y-shaped
pipe (11) which, in turn, is connected to the negative pres-
sure point of the flue pressure switch (5) and to the pressure
point (4)on the fan.
e positive pressure point (10) is connected directly to the
inside of the sealed chamber.
Flue pressure switch (5).
(until serial number 3078554)
It is located at the top, inside the sealed chamber and, by means
of the relative points, measures the difference in pressure be-
tween the outlet of a Venturi tube fitted on the fan exhaust
(negative signal) and the inside of the sealed chamber itself
(positive signal).
e signal measured by the pressure switch varies according
to the length of the intake/exhaust ends and can be measured
by the relative pressure points located at the top of the sealed
chamber (9-10).
When the switch trips it causes a contact (S6) to close which
controls the integrated circuit, enabling or preventing burner
ignition.
Flue pressure switch
triggering pressures
ON
Pa (mm H2O)
OFF
Pa (mm H2O)
EOLO Star 23 kW 150 (15.3) 130 (13.26)
(from serial number 3078555)
It is located at the top, inside the sealed chamber and, by
means of the relative points, measures the difference in pressure
between the fan output (negative signal) and the inside of
the sealed chamber itself (positive signal).
e signal measured by the pressure switch varies according
to the length of the aspiration/exhaust terminals and can be
measured by the relative pressure points located at the top of
the sealed chamber (9-10).
When this switch trips it causes a contact (S6) to close that
acts on the integrated board, enabling or preventing burner
ignition.
Flue pressure switch
triggering pressures
ON
Pa (mm H2O)
OFF
Pa (mm H2O)
EOLO Star 23 kW 44 (4.5) 36 (3.7)
Fan (3).
e extractor works downstream from the combustion cham-
ber and is secured vertically to the top of the hood (2) from
which it extracts the fumes, conveying them to the exhaust
pipes to which the boiler is connected. At the same time it
guarantees the flow of air inside the sealed chamber.
It is controlled by the integrated board and its operation ba-
sically coincides with that of the burner.
(until serial number 3078554)
A Venturi tube is fitted inside its exhaust outlet and the
flue pressure switch’s (5) negative signal is measured at its
outlet.
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Technical DocumentationTechnical Documentation
e EOLO Star 23 kW is designed for being connected to the
special intake/exhaust coupling pipes.
(until serial number 2972938) It is possible to use the concen-
tric flue pipes (Ø60/100 and Ø80/125), only.
(from serial number 2972939) over than the concentric flue
pipes (Ø60/100 and Ø80/125) it is also possible to use the
Ø80/80 coupling type separator kits.
ese kits are able to split the air inlet and discharge of the
exhaust flues.
Sealed chamber, fan-assisted configuration
(type C).
Exhaust.
Connection to the fumes exhaust pipes is through a flange (1)
or a flanged curve to fix to the fitting (4) at the top of the sealed
chamber, placing a shaped seal in between (6).
e flange differs according to whether the system is used split
or concentric.
In the first case, the passage for the intake of combustion air
(5) is closed while in the second case it is used.
To ensure correct operation of the boiler it is necessary to put
a diaphragm (7) on the exhaust fitting (4), between it and the
flange used (1).
ere are different diameter diaphragms, mounted accord-
ing to the type of pipe and its length (see boiler instruction
booklet).
Intake.
Using the split system, connection to the intake pipes is done
in exactly the same way as for the exhaust pipes, connecting
to one of the two 80 mm Ø holes (2) at the top of the sealed
chamber.
e unused hole is closed with one of the plastic caps (3) sup-
plied with the boiler.
If coaxial pipes are used, the intake of combustion air is done
exploiting the concentric hole, outside the exhaust fitting
(5).
Intake and Exhaust Kits.
e kits and their accessories permit use of four concentric
systems and two split systems.
As regards pressure losses relating to each accessory, the various
possible combinations and the use of the diaphragms depend-
ing on the length of the pipes used, follow the instructions
given for the intake and exhaust terminals (see the boiler
instruction booklet).
e coupling of the accessories (bends, extensions and termi-
nals) is the fitted type while sealing is guaranteed by silicone
lip seals.
Coupling type horizontal concentric kit Ø 60/100.
e exhaust pipe (60 mm Ø) is fitted inside the aspiration
pipe (100 mm Ø).
Connection to the boiler is done using a 90° bend (2) that can
be positioned in any direction and which, by means of the
necessary extensions, is connected to the specific aspiration
and exhaust terminal (3).
e maximum overall permitted length beyond the first bend
(2) is 3 straight horizontal metres.
Extraction and exhaust systems.
Coupling type horizontal concentric kit Ø 80/125.
e exhaust pipe (80 mm Ø) is fitted inside the aspiration
pipe (125 mm Ø).
Connection to the boiler is done using a 90° 60/100 Ø bend
(2) that can be positioned in any direction and which, by
means of the 60/100-80/125 adapter (3) and necessary ex-
tensions, is connected to the specific aspiration and exhaust
terminal (4).
e maximum overall permitted length beyond the first bend
(2) is 7.3 straight horizontal metres.
1
2
3
4
5
7
6
1
3
2
45
1
3
2
56
4
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Coupling type vertical concentric kit Ø 80/125.
e exhaust pipe (80 mm Ø) is fitted inside the aspiration
pipe (125 mm Ø).
Connection to the boiler is done using a flange (2) that, by
means of the 60/100-80/125 adapter (3) and necessary ex-
tensions, is connected to the specific aspiration and exhaust
terminal 80/125 with aluminium tile (6).
e maximum overall permitted length is 12.2 straight verti-
cal metres.
Coupling type vertical concentric kit Ø 60/100.
e exhaust pipe (60 mm Ø) is fitted inside the aspiration
pipe (100 mm Ø).
Connection to the boiler is done using a flange (2) that, by
means of the necessary extensions, is connected to the specific
aspiration and exhaust terminal 60 /100 with aluminium
tile.
e maximum overall permitted length is 4.7 straight verti-
cal metres.
80/80 Ø coupling type separator kit.
Both pipes are 80 mm in diameter.
Connections to the boiler are done using the two specific
flanges that allow discharge (4) from the centre fitting and
aspiration (3) from one of the two side holes.
e maximum permitted length (aspiration + exhaust) is 33
straight horizontal metres and 41 straight vertical metres.
To avoid condensate problems, the exhaust pipe is limited to
a maximum of 5 metres.
80/80 Ø insulated coupling type separator kit.
Both pipes are 80 mm in diameter.
Connections to the boiler are done using the two specific
flanges that allow discharge (4) from the centre fitting and
aspiration (3) from one of the two side holes.
Insulation is by way of the seals (6) which create an air gap
with the external concentric 125 mm Ø pipe.
e maximum permitted length is 33 straight metres (aspira-
tion + exhaust).
To avoid condensate problems, the exhaust pipe is limited to
a maximum of 12 metres.
1
2
3
4
6
57
8
4
6
5
1
3
2
78
5
9
7
5
4
1
3
2
5678
8
910
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e electrical circuit of the EOLO Star 23 kW boiler is man-
aged 100% by a microprocessor driven p.c.b. which controls
the boiler’s functions.
Some of the control and safety devices operate at mains voltage
(230 Vac) while others at low voltage.
Electrical circuit.
230 V AC circuit.
Safety devices and controls.
It detects burner ignition, being hit by its flame.
It’s connected to the integrated board.
Detection electrode
(E2)
ey interrupt power to the circuit when power input is over
3.15 A.
ey are mounted on the integrated board.
Line fuse (F1)
Neutral fuse (F2)
Fuse
3.15 AF 250 V
Legend:
B1 - Delivery probe
B2 - D.h.w. probe
CRD - Remote digital control (optional)
DS1 - Display
E1 - Ignition electrode
E2 - Detection electrode
E4 - Safety thermostat
F1 - Line fuse
F2 - Neutral fuse
M1 - Boiler circulator
M20 - Fan
S2 - Functioning button
S3 - Block reset push button
S4 - D.h.w. flow switch
S5 - System pressure switch
S6 - Flue pressure switch
S20 - Room thermostat (optional)
S21 - D.h.w. temperature increase push
button
S22 - D.h.w. temperature decrease push
button
S23 - Central heating temperature
increase push button
S24 - Central heating temperature
decrease push button
T1 - Ignition transformer
T2 - Boiler board transformer
X40 - Room thermostat jumper
Y1 - Gas valve
Y2 - Gas valve modulation coil
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Loads.
is board is always powered regardless of the position of the functioning button (S2)
(see integrated board operation).
Integrated board
It is powered by the integrated board when there’s either a central heating or antifreeze
request.
It permits circulation in the primary circuit.
Boiler circulator
(M1)
It is powered at mains voltage by the integrated board when it is necessary to ignite the
burner.
It permits the flow of gas to the burner.
Gas valve (Y1)
(main coils)
It is controlled by the integrated board that provokes a spark between its end and the
burner surface that ignites the air/gas mix.
Ignition electrode
(E1)
It ensures the flow of air inside the sealed chamber and the exit of fumes produced by
combustion.
It is powered by the integrated board.
Fan
(M20)
Low voltage circuit.
is device is to control the appliance remotely (SUMMER / WIN-
TER selection, setting and indicating temperatures, displaying alarms,
resetting, etc.) and acts as a weekly timer/room thermostat.
If the CRD is installed the X40 jumper must be removed.
Remote digital control
(CRD)
(optional)
See Remote
Digital Control
Operation
(CRD)
is switch acts on the integrated board after some domestic water
has been drawn, causing the boiler to work in the d.h.w. mode.
When idle it enable operation in the central heating mode.
D.h.w. flow switch
(S4)
Interrupted
contact
Safety devices and controls.
When pressure in the boiler circuit is below 0.3 bar the burner
switches off.
System pressure switch
(S5)
Interrupted
contact
is acts on the integrated board and enables burner operation
when the fumes are expelled correctly.
When closed and the fan is off, it does not enable the start of the
ignition cycle.
Flue pressure switch
(S6)
Changing
contact
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e possible functioning selections are:
= Circuit powered, the antifreeze and antiblock functions
are still active, the various post circulation and post ventilation
functions are completed.
( ) = Boiler operation in SUMMER.
( ) = Boiler operation in WINTER.
Functioning button
(S2) Push button
e burner switches off when the safety temperature is exceeded
(105 °C).
It is located at the main exchanger outlet.
Safety thermostat
(E4)
Clicson
thermostat with
normally closed
contact
It lets the integrated board measure the temperature of the delivery
water in the primary circuit.
If it breaks the burner stops working whether in the central heating
or d.h.w. mode.
It is located on the central heating delivery pipe of the bithermal
exchanger.
Delivery probe
(B1)
NTC probe
10 kohm 25 °C
It lets the integrated board measure the outlet temperature of the
domestic hot water.
If it breaks, functioning in the d.h.w. mode is stopped but function-
ing in the central heating mode is allowed.
It is inserted in the d.h.w outlet pipe connected to the bithermal
exchanger.
D.h.w. probe
(B2)
NTC probe
10 kohm 25 °C
It is powered by the integrated board with a variable continuous current.
It permits varying of the gas pressure to the burner.
Gas valve modulation coil
(Y2)
Loads.
It enables operation in the central heating mode when room tem-
perature is below that required.
If this room thermostat is installed the X40 jumper must be re-
moved.
Room thermostat (S20)
(external optional)
Interrupted
contact
It unblocks the boiler following either the ignition failure or over-
temperature safety device triggering; it can be used to activate the
chimney sweep function.
If pressed together with the functioning button (S2) it lets you
access the boiler parameter settings.
Reset push button
(S3) Push button
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Electrical circuit.
Central heating phase.
Working with the room thermostat.
By selecting the (Winter) functioning mode with the (S2)
push button the boiler is enabled to work in the central heat-
ing mode.
When the room thermostat (S20) closes the integrated board
powers the boiler circulator (M1) by means of relay K3.
In the meantime, if the flue pressure switch (S6) contact is
idle “NC”, the adjustment circuit powers the fan (M20) by
means of relay K4.
If the following conditions occur: the system pressure switch
contact (S5) is closed (pressure in the primary circuit higher than
the minimum value), the safety thermostat (E4) is enabled, the
flue pressure switch contact (S6) is in “NO” position and the
temperature read by the NTC delivery probe (B1) is below the
value set on the boiler’s control panel, then the P.C.B. energises
the request relay K2.
is operation causes the closing of the 2 contacts which starts
the ignition cycle, first of all supplying the ignition electrode
(E1) and then both the coils of the gas valve (Y1).
Burner ignition is detected by the integrated board by means
of the ionisation electrode (E2).
Remote digital control operation.
By selecting the Winter functioning mode on the Remote
Digital Control (CRD) panel, the boiler is enabled to work
in the central heating mode.
If the conditions detected by the CRD require ignition in the
central heating mode, the integrated board powers the boiler
circulator (M1) via the relay K3 and the burner ignites as
described above.
Note: With each switching off when the temperature is
reached, the integrated board stops the burner working in
the central heating mode for a time equal to that set with the
board parameters (see integrated board operation).
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
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Electrical circuit.
D.h.w. phase.
Operation.
By selecting the (Summer) or (Winter) functioning
mode with the (S2) push button the boiler is enabled to work
in the domestic hot water mode.
When some domestic water is drawn it causes the d.h.w. flow
switch (S4) contact to close and enables operation in the
d.h.w. mode.
e boiler circulator (M1) is not started in the domestic hot
water mode or is switched off if there is an ongoing central
heating request upon opening of relay K3.
If the temperature read by the NTC d.h.w. probe (B2) is below
the value set on the boiler’s control panel (or on the CRD if
installed) and if the fumes pressure switch contact (S6) is idle
“NC”, the adjustment circuit powers the fan (M20) by means
of relay K4.
If the contact of the system pressure switch (S5) is closed (pres-
sure in the primary circuit higher than the minimum value) the
board, being enabled by the safety thermostat (E4) and with
switching of the flue pressure switch to “NO” (S6), closes the
contact of the request relay K2 which causes the 2 contacts
to close and the ignition cycle to start, first of all triggering
the ignition electrode (E1) and then both the coils of the gas
valve (Y1).
Burner ignition is detected by the integrated board by means
of the ionisation electrode (E2).




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
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