9
1.2.2. Operation
CENTRAL HEATING
Use the regulation knob (11, pic. 1) to set the temperature in the central heating system.
The temperature setting range is 35-78°C (from the counter-clockwise limit position to the time limit position).
The CH temperature can be read from lights 2÷7 (pic. 1) on the control panel.
To prevent frequent ignition and switching off in heating mode, the boiler has a 4-minute waiting time between subsequent ignitions.
If the water temperature in the system fall below 40°C, waiting procedure is aborted and the boiler re-ignites (
Antifast
function).
DHW
The domestic hot water supply function is active on models CTN and CTFS, and on models RTN and RTFS with an (optional) external water
heater. This function always has priority over central heating water.
For models CTN and CTFS, the temperature setting range is 35-57°C (from the counter-clockwise limit position to the time limit of regulation
knob 10).
For models RTN and RTFS with an (optional) external water heater with an NTC probe (10 kΩ @ β=3435; refer to the water heater specifica-
tions), the temperature setting range is 35-57°C (from the counter-clockwise limit position to the time limit of regulation knob 10).
For models RTN and RTFS with an (optional) external water heater with thermostat probe, the desired HDW temperature must be set on the
water heater (refer to the attached instructions). Regulation knob 10 has no effect on this configuration.
The boiler is fitted with a flow-limiting device that allows a maximum DHW flow of 10 litres per minute.
The DHW flow rate depends on the boiler’s thermal capacity and the mains water supply temperature, and can be calculated from the fol-
lowing formula:
K
l = DHW litres per min. = ---
Δ
T
K represents:
- 334 (CTN 24)
- 341 (CTFS 24)
- 410 (CTFS 28)
Δ
T = DHW temperature – mains water supply temperature
E.g. In model CTFS 24, if the mains water supply temperature is 8°C and DHW is required at 38°C, the value of
Δ
T is:
Δ
T = 38°C – 8°C = 30°C
and DHW litres (l per minute) available at the required temperature of 38°C is
I = 341 / 30 = 11.4 [litres per minute - mixed water to the tap]
ANTI-FREEZE
This boiler is fitted with an anti-freeze protection system, which works when the following functions are activated: SUMMER, WINTER and
ANTI-FREEZE.
The anti-freeze function only protects the boiler, not the whole heating system.
The heating system must be protected using a room thermostat, although this is disabled when the selector is set
to the ANTI-FREEZE or OFF mode.
Therefore, if you want to protect both the boiler and the system, turn to WINTER mode
on selector 9.
When the heating water temperature sensor detects a water temperature of 5°C, the boiler switches on and stays on at its minimum thermal
power until the temperature reaches 30°C or 15 minutes have elapsed. The pump continues to operate even if the boiler shuts down.
In models CTN and CTFS, anti-freeze function also protects the DHW circuit.
When the DHW temperature sensor detects a temperature of 5°C, the boiler switches on and stays on at its minimum thermal power until the
temperature reaches 10°C or 15 minutes have elapsed (the deviating valve is in the DHW position). The pump continues to operate even if the
boiler shuts down.
