Immergas CAESAR 14 Star Guide

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CAESAR STAR
Instantaneous wall-hung room
sealed fan-assisted water heater.
CAESAR 14 Star
General features.
CAESAR Star is a room-sealed water heater featuring
an electronic flame modulation system for regulating
the temperature thanks to a microprocessor-controlled
modulation board and flow and temperature sensors.
CAESAR 14 Star features standard electronic burner
ignition and a wet combustion chamber copper
e changer.
Notwithstanding its very compact size, the appliance
has a power of 21,000 Kcal/h (24.4 kW) corresponding
to a flow of 14 l/min with ∆T 25°C.
CAESAR 14 Star is factory set for connecting to the
broad range of couple-on aspiration and e haust kits
with silicone seals and, thanks to a special cover kit
(optional), it can be installed in open chamber and fan-
assisted configuration (B22). Another optional feature
is an antifreeze safety device that protects it against
temperatures as low as -15°C.

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Main dimensions.
Key:
U - domestic hot water outlet
G - as supply
E - d.h.w. inlet
V - power connections
)mm(thgieH)mm(htdiW)mm(htpeD
036573052
snoitcennoC
SAGRETAWTOHCITSEMOD
GUE
"4/3"2/1"2/1

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CAESAR Star main component parts.
Key:
1 - Sealed chamber
2 - Fume expulsion fan
3 - D.h.w. exchan er
4 - I nition/detection low electrode
5 - Gas valve
6 - D. h. w. NTC probe
7 - Fan safety pressure switch
8 - Overheat. safety thermostat
CAESAR Star Control anel.
Key:
1 - Bathroom water heater stop red indicator
li ht
2 - Flame yellow indicator li ht
3 - Operation switch: 0/ (Reset) and on
temperature switch
9 - Flow limiter
10 - 10 bar safety valve / one way valve
11 - Flow meter
12 - Drau ht diverter.
13 - Combustion chamber
14 - Burner
15 - D.h.w. limit thermostat
16 - Cold water inlet cock

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Hydraulic circuit.
Key:
1 - Fume extraction fan
2 - Sealed chamber
3 - Exchan er
4 - Main burner
5 - Gas valve
6 - D.h.w. adjustment NTC probe
7 - Overheat. temp. safety thermostat
8 - Air pressure switch
9 - Drau ht diverter
10 - Exchan er safety thermostat
11 - Flow limiter
12 - 10 bar safety valve
13 - One way valve
14 - Flow meter
15 - Water inlet filter
16 - D.h.w. inlet cock
U - D.h.w. outlet
G - Gas supply
E - D.h.w. inlet

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Hydraulic circuit.
The hydraulic circuit with relevant control and safety
devices is engaged every time there is a request for
domestic hot water.
Operation.
Drawing at least 2.5 l/min of domestic hot water means
a flow of cold water inside the flow measuring device
(14) and consequent enabling of operation.
Following this, the adjustment circuit ignites the burner.
This way the heat generated by the flame and con-
tained in the fumes produced by combustion is
absorbed by the copper blades of the water-gas
e changer (3) which in turn transfers the heat to the
water flowing inside.
Exchanger.
This is a water-gas e changer (1) with pipes and flaps
in copper at the e it of which is positioned the
overheating safety thermostat (2).
It is of the so-called “wet chamber” type because the
lower part (3) around which is wrapped the hot water
outlet pipe (4), represents in fact the combustion
chamber.
NOTE: to maintain the characteristics of efficiency of
the e changer, we recommend installing a
“polyphosphate dosing” kit if the water is such as to
have characteristics that could create scale on the
pipes (recommended when water hardness exceeds
25 French de rees).
Safety devices and controls.
Flow meter (1).
This is a rotating magnetic sensor fitted at the cold
water flow inlet.
By means of a three-pole connector (2) it is electrically
connected to the adjustment board, allowing this to
measure the flow of water to determine minimum
ignition value (2.5 l/min) and optimise temperature
adjustment.
10 bar safety valve unit (1).
Prevents safety pressure (10 bar) being e ceeded in
the hydraulic circuit of the water heater.
It is connected to the cold water inlet pipe.
Inside is a 10 l/min flow limiter (2) and a one way valve
that prevents the return of hot water towards the mains
supply.

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The circuit consists of an atmospheric burner and a
modulating type valve for gas combustion and gas flow
adjustment respectively.
Operation.
When the main coils (3) are energised, both inner val-
ve shutters open, allowing the gas to flow towards the
burner.
The flow rate/outlet pressure is regulated by means of
the gas valve stabiliser and the modulation coil (1).
By means of the burner nozzles (6), the fuel is injected
into the venturi pipes (ramps) inside which the air-gas
mi is obtained that is ignited by the spark from the
ignition electrode (5).
Modulating gas valve.
The gas valve (SIT 845) features two main coils (3)
and a modulation coil (1) controlled by the modulation
board.
The ma imum and minimum outlet pressure settings
can be made on this valve (see as adjustments).
Main electrical coils (3).
Two coils of the ON-OFF type energised (230V AC)
by the adjustment board when the burner has to be
ignited.
These are electrically connected in parallel and
energised by mains power through a special connec-
tor (2).
Modulation coil (1).
This is a low-voltage coil controlled by the modulation
board.
This controls the gas valve stabiliser and permits
changing the outlet pressure in a way proportionate to
the DC signal that runs through it.
Gas circuit.
Burner.
The burner consists of 12 horizontal venturi pipes (4)
in which the gas is injected by an equal number of
nozzles (6) mounted on the special header (7).
Ignition occurs by means of the adjustment board which
controls the ignition/detection electrode (5).
Ignition and detection electrode (5).
During ignition, this is controlled by the adjustment
board which produces an electrical charge between
its end and the burner surface that ignites the air-gas
mi .
When the burner is on, it also detects the flame on the
burner enabling the adjustment board to conclude the
ignition cycle and change the gas pressure according
to need.
This is positioned on the front of the burner in line with
the centre ramp.

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Gas adjustments.
Ma and minimum gas pressure adjustments can be
made by means of the gas valve respecting the values
shown on the tables relating to the type of
corresponding gas.
Measurements are made using a U-shaped differen-
tial pressure gauge connected to a “Y” to be placed in
between in the small silicone tube connecting the gas
valve to the sealed chamber and to the gas valve outlet
pressure point.
Valve Sit 845.
Maximum pressure setting.
Draw d.h.w. after setting the temperature switch at
ma imum.
Turn the brass nut (3) clockwise to increase the
pressure to the burner and anticlockwise to decrease
it.
Adjusting minimum pressure
(to be done after adjusting max pressure).
After interrupting power to the modulation coil, turn the
crosshead screw (2) clockwise to increase pressure
to the burner and anticlockwise to decrease pressure.
Key:
1 - Coil
2 - Minimum output setscrew
3 - Maximum output setscrew
4 - Gas valve outlet pressure point
5 - Gas valve inlet pressure point
6 - Protection cap
Valvola Sit 845
Changing type of gas.
Adaptation to a type of gas different to that for which
the boiler is intended, can be done by using the special
kits (natural as or LPG).
The changeover consists in replacing the burner
nozzles and in moving to the modulation board of the
“NATURAL GAS- LPG” (S1) bridge.
The minimum and ma imum pressures are then set
on the gas valve in the way described above.
The burner ignition pressure is not adjusted
because the type of board operation does not require
such setting (see modulation board operation).
NOTE: any changes made to enable the unit to use
G110 gas (town as), besides the use of a special
nozzle kit and performance of the same operations
indicated above, also requires shifting jumper switch
“S1” onto switch “S2” on the electronic board (see
modulation board adjustments).

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Operation.
The products of combustion, after investing the water-
gas e changer (3), are conveyed to a draught diverter
(5) on top of which the fume e tractor (fan) (1) is fitted.
Fan operation ensures forced e pulsion of the fumes
and, at the same time, creates a vacuum in the sealed
chamber (2) so the combustion air can be e tracted
from outside.
Correct fume e traction is controlled by a special
pressure switch (4), the operation of which enables or
prevents the burner from igniting.
Fume pressure switch (4).
Positioned in the top inner part of the sealed chamber
and detects, by means of special pressure points, the
difference in pressure between the top of the draught
diverter (the point where the extractor is positioned
and operates) and the inside of the sealed chamber.
Operation of this switch causes a microswitch (S3) to
close. This affects the adjustment board and either
enables or prevents burner ignition.
Fan (1).
The e tractor operates downstream of the combustion
chamber and is fitted vertically in the top part of the
draught diverter (5) from which it e tracts the fumes
and conveys these into the e haust pipes to which the
boiler is connected.
Fume circuit.
It is controlled by the adjustment board and its
operation coincides with that of the burner.

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Extraction and exhaust systems.
The CAESAR Star is set for connecting to the coupling
e traction/e haust ducts and can be installed in sealed
chamber fan-assisted configuration (type C) or, thanks
to a special kit, in open chamber fan-assisted version
(type B22).
As regards the load losses relating to each accessory
and the various possible combinations and the use of
diaphragms to be fitted according to the length of the
pipes, see instructions relating to extraction and
exhaust ends (CAESAR Star instruction booklet).
Accessories (bends, extensions and end pieces) are
joined by coupling and seal is provided by special
silicone lip seals.
Open chamber and fan-assisted (type
B22) configuration for installation
outdoors in a partially protected area
(see illustration alongside).
Using a special cover (4) to be placed on the top part
of the sealed chamber, the CAESAR Star appliance
can be fitted in a partially protected place.
This way the appliance works in open chamber and
fan-assisted (B22) configuration.
Extraction.
To fit the cover (4), the two caps (1) that close the
holes in the top part of the sealed chamber must be
removed.
The e traction of comburent air is done directly from
the environment e ploiting the free space between the
lower part of the cover (4) and the upper part of the
boiler.
Exhaust.
The 80 mm diameter union to the e haust ducts is
obtained by means of a flange (3) used in doubled
systems.
The use of special accessories permits horizontal type
(A) or vertical type (B) e haust.
To avoid condensation problems, the e haust duct
must be restricted to 5 metres for normal pipes and
12 metres for insulated pipes.

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Sealed chamber fan-assisted
configuration (type C).
Exhaust.
Connection to the e haust pipes is by means of a
flange (1) or a flanged bend to be fitted on the centre
hole (6) on the top section of the sealed chamber,
placing in between a special shaped seal (5).
This flange differs according to whether the doubled
or concentric system is used.
In the former case, the duct for the combustion air (8)
is closed, while in the latter case it is used.
To ensure correct boiler operation, a diaphragm (7)
will have to be fitted on the e haust pipe (6) between
the flange used (1).
Diaphragms are envisaged of different diameter which
must be fitted according to the type of duct and its
length (see CAESAR Star instruction booklet).
Extraction.
Using the doubled system, connection to the e traction
ducts is done in the same way as for the e haust pipes,
linking up to one of the two holes with diameter 80 mm
(2) on the top section of the sealed chamber.
The hole which is not used is closed using one of the
caps (3), placing in between the relevant seal (4) fea-
tured on the appliance.
If coa ial pipes are used, e traction is done by e -
ploiting the concentric hole outside the e haust pipe
(8).
Extraction and Exhaust Kits.
The kits with the relevant accessories make it possible
to use two concentric systems and a doubled
system.As regards flow resistance relating to each
accessory, the various possible combinations and use
of the diaphragms to be installed according to the
length of the ducts, see the instructions relating to the
e traction and e haust ends (CAESAR Star
instruction booklet).
The accessories (bends, extensions and end pieces)
are connected by means of slot-in couplings and seal
is ensured by means of silicone-lip seals.
Horizontal concentric slot-in kit Ø 60/100.
The e haust pipe (Ø 60 mm) is fitted inside the
e traction pipe (Ø 100 mm).
Connection to the boiler is by means of a 90° (2) fully
adjustable bend which, by means of the necessary e -
tensions, must be connected to the e traction and e -
haust end piece (3).
The ma imum overall length allowed beyond the first
bend (2) is 3 straight horizontal metres.