26
7.1
CHECKING APPLIANCE OPERATION
When carrying out any repairs or servicing to the
appliance, the relevant commissioning procedure
must be undertaken to ensure the continued safe
operation of the appliance. Particular attention
should be made to ensure gas soundness, water
soundness, and the electrical integrity of the
appliance.
7.2
APPLIANCE MODES OF OPERATION
NOTE
There must be sufficient system water pressure
(min. 0.5 bar) to ensure the water pressure switch
is activated. If there is insufficient system pres-
sure the pump and fan will be prevented from
operating and the low-pressure fault indicator will
be displayed.
7.2.1
SELECTOR SWITCH IN THE OFF POSITION
When the selector switch is in the STANDBY
position, no status indicators (see fig. 1A) are
displayed.
Active functions
:
●
Frost-protection system
●
Pump anti-block
●
Valve actuator anti-block.
7.2.2
BOILER “ON” IN WINTER MODE
When the function switch is in the
Winter position,
the relevant status indicators (see fig. 1A) are
displayed and the appliance is active for both
heating and DHW requests.
Active functions
:
●
DHW pre-heat
●
Booster function
●
Frost-protection system
●
Pump anti-block
●
Valve actuator anti-block.
7.2.3
BOILER “ON” IN SPRING MODE
When the function switch is in the
Spring position,
the relevant status indicators (see fig. 1A) are
displayed and the appliance is active for DHW
requests.
Active functions
:
●
Frost-protection system
●
Pump anti-block
●
Valve actuator anti-block.
7.2.4
BOILER “ON” IN SUMMER MODE
When the function switch is in the
Summer posi-
tion, the relevant status indicators (see fig. 1A) are
displayed and the appliance is active for DHW
requests.
Active functions
:
●
TSC function
●
Frost-protection system
●
Pump anti-block
●
Valve actuator anti-block.
7.2.5
BOILER “ON” IN AUTUMN MODE
When the function switch is in the
Autumn posi-
tion, the relevant status indicators (see fig. 1A)
SECTION 7 CHECKS, ADJUSTMENTS AND FAULT FINDING
are displayed and the appliance is active for both
heating and DHW requests.
Active functions
:
●
SARA function
●
TSC function
●
Frost-protection system
●
Pump anti-block
●
Valve actuator anti-block
7.2.6
APPLIANCE FUNCTIONS
●
●
●
●
●
DHW pre-heat:
this function is only active when
there are no requests for heating or hot water.
The pre-heat function has priority on CH request.
When the secondary thermistor drops to 35°C,
the pre-heat function is enabled, the appliance
operates on minimum power until the second-
ary thermistor reaches 55°C. Thereafter the
pump and fan will over-run.
●
SARA:
this function will automatically raise the
outlet flow temperature when the heating tem-
perature selector is in the 55-65°C range, if the
appliance is unable to reach the room tempera-
ture set with room thermostat.
●
TSC:
the temperature stability control function
(TSC) ensures that a steady temperature is
maintained. This is achieved by the TSC func-
tion overriding the set DHW temperature – if
necessary – during DHW operation/requests
rather than switching the burner off when the set
temperature is reached.
●
Booster function:
this function will automati-
cally raise the flow outlet temperature if/when
the appliance is unable to reach or maintain the
desired flow outlet temperature (Heating).
●
Frost-protection:
this function is only active
when there are no requests for heating or HW.
Should the temperature of the primary thermis-
tor drop below 7°C, the valve actuator will mo-
tor to the heating position. Should the tempera-
ture of the primary thermistor exceed 10°C dur-
ing this period, the cycle will be aborted. If the
temperature drops below 4°C, the boiler will op-
erate on minimum power until the temperature
of the primary thermistor reaches 30°C. There-
after the pump & fan will over-run for 30-sec-
onds.
●
●
●
●
●
Pump/actuator anti-block cycle:
when there
has been no heating or HW request for 24-hours,
the anti-block cycle is activated. The valve
actuator will motor from the DHW position to the
heating position for a period of 10-seconds and
then motor back to the DHW position. Thereafter
the pump will be activated for a period of 1-
minute. If the selector switch is in the Heating &
HW position, the fan will also be active for 1-
minute.
7.2.7
HEATING MODE
With the selector switch in the autumn or winter
position and any additional controls (time clock,
room thermostat, etc,) calling for heat, the appli-
ance will operate in the heating mode.
The valve actuator will motor to the heating posi-
tion and the pump and fan will be activated via the
