6
1.2 Operating the boiler
1.2.1 Switching on
• Open the gas stop cock.
• Connect power mains to the
boiler (no.1 light on control panel
turns on).
• Choose boiler mode by turning
the “OFF/summer/winter/anti-
freezing” selector (9).
• Adjust CH temperature adju-
stment knob (11) to set the tem-
perature required for the heating
system.
• Adjust DHW water temperature
knob (10) to set the temperatu-
re required for the DHW (CTN,
CTFS).
• Set room temperature by means
of a room thermostat (if installed).
• When CH is required, no. 8 light
comes on.
WARNING:
should the boiler be
left inactive for a long time, par-
ticularly if boiler is LPG powered,
ignition might be difficult.
Before starting the boiler switch
on another gas powered device
(e.g. kitchen range, oven, etc.).
Beware that even by following this
procedure, the boiler might still
experience some starting difficul-
ties and shut down once or twice.
Reset boiler by acting on (9) knob
(see paragraph 1.2.4).
1.2.2 Operation
To prevent frequent ignition and
switching off in the heating mode,
the boiler has a 4 minute waiting
time between subsequent igni-
tions. Should water temperature
in the system fall below 40°C,
waiting time procedure is aborted
and boiler re-ignites.
Boiler electronics always gives
priority to DHW over CH supply.
DHW temperature can be adjusted
within a 35°C to 62°C range.
The boiler is fitted with a flow-limi-
ting device that allows a maximum
DHW flow of 10 litre per minute.
DHW litre per minute flow depen-
ds on the boiler’s thermal capacity
and water mains supply tempera-
ture, according to the following
formula:
l = DHW litre per min. = K
6
T
K represents:
- 334 (CTN 24)
- 341 (CTFS 24)
- 410 (CTFS 28)
6
T = DHW temperature – water
mains supply temperature
E.g. In CTFS 24 model, should
water mains supply temperature
be 8°C and DHW is required to be
38°C, the value of
6
T is:
6
T = 38 °C – 8 °C = 30 °C
and DHW litre (l per minute) avai-
lable at the required temperature
of 38°C is
I = 341 = 11.4 [litre per minute -
30
mixed water to the
tap]
This boiler is fitted with anti-free-
zing protection system.
The anti-freezing function is acti-
ve when selector 9 is in the sum-
mer/winter/anti-freezing and OFF
modes.
Please Note: The anti-freezing
function only protects the boiler
and not the heating system.
The heating system must be pro-
tected by using a room thermo-
stat, although this is disabled
when the selector is set to the
anti-freezing mode.
Therefore, if you want to protect
both the boiler and the system,
select the winter mode with
selector 9.
When selector 9 is set on the OFF
position, anti-freezing function is
not active.
When the heating water tempera-
ture sensor detects a water tem-
perature of 5°C the boiler switches
on and stays on at its minimum
thermal power until the tempera-
ture of the CH reaches 30°C or 15
minutes have elapsed.
Should the boiler shut down, pump
operation continues.
In CH only boilers equipped with
a DHW supply external cylinder,
anti-freezing function protects
cylinder as well.
When DHW temperature sensor
detects a water temperature of
5°C the boiler switches on and
stays on at its minimum thermal
power until the temperature of
DHW reaches 10°C or 15 minutes
have elapsed.
Should the boiler shut down, pump
operation continues.
CH system can be effectively pro-
tected from freezing by means of
specific anti-freezing addictives
suitable in multi-metal systems.
Do not use car engine anti-free-
zing products, and periodical-
ly check anti-freezing product
effectiveness.
Where the boiler is to remain inac-
tive and
is not disconnected from
the electric mains power supply,
the circulation pump is activated
for 6 seconds every 24 hours to
prevent seizure.
1.2.3 External temperature probe
operation
The boiler can be fitted with an
external temperature probe through
which the boiler adjusts CH water
temperature accordingly, in other
words increasing CH water tempe-
rature when external temperature
decreases and vice-versa. External
probe favors efficient and energy
conserving boiler operation.
Boiler electronics microprocessor
program determines CH water tem-
perature accordingly to external
probe information.
When an external temperature
probe is wired to the boiler, CH
water temperature knob settings
determine boiler operational mode
as shown in pic. 2.
When CH water temperature knob
is set to max., CH water tempe-
rature will gradually increase from
min. value, when external tempe-
rature is 25°C, to max. temperature
of 83°C when external temperature
is 10°C.
pic. 2
