22
Compact
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
AT REST MODE
When the appliance is at rest, (no demand for
heat or water) the green LED will be illuminated
to indicate there are no faults, if the appliance has
been inactive for aproximately 24 hours, it will
energise the pump for a short period to ensure
the pump does not seize due to inactivity. The
appliance also has built-in frost protection, which
will operate even if the mode selector switch is in
the ‘off’ position.
7.3
HOT WATER MODE
Opening a hot water outlet and enabling a flow
rate of 2 litres or more, causes the domestic water
flow switch to activate. Activation of the domestic
hot water flow switch allows the fan to run. When
the fan is running it proves (switches) the air
pressure switch. The air pressure switch delivers
current to the PCB and enables an ignition se-
quence to begin. The ignition sequence begins
with the energising of the gas valve and a simul-
taneous sparking at the spark/sense electrode.
This will continue for aproximately 10 seconds or
until successful ignition has been established. (If
no ignition has been established within the ten
seconds, the ignition attempt will be terminated
and the appliance will go to lockout). When ignition
has been established, the appliance will quickly
achieve and maintain the desired hot water tem-
perature (see 5.13). The appliance monitors the
setting of the hot water potentiometer against the
temperature of the secondary thermistor, and
increases or decreases current to the modulating
coil, this in turn adjusts the burner pressure, thus
enabling the temperature to be maintained to
within a few degrees. When the temperature of
the secondary thermistor exceeds the setting of
the hot water potentiometer, ignition will be termi-
nated until the temperature drops.
NOTE
The primary thermistor will overide the secondary
thermistor if the temperature of the primary
thermistor exceeds 80 ºC.
When the mode selector switch is set to heating
and hot water, the pump will over-run for 30
seconds after any demand for heating or water
has been satisfied.
When the mode selector switch is set to hot water
only, the fan will over-run for one minute if the
temperature of the primary thermistor exceeds
55 ºC.
7.4
HEATING MODE
With all controls calling for heat, the pump and fan
will run. When the fan runs it proves the air
SECTION 7 CHECKS, ADJUSTMENTS AND FAULT FINDING
pressure switch. The air pressure switch delivers
current to the PCB and enables an ignition
sequence to begin. The ignition sequence begins
with the energising of the gas valve and a
simultaneous sparking at the spark/sense
electrode. This will continue for approximately 10
seconds or until successful ignition has been
established. (If no ignition has been established
within the ten seconds, the ignition attempt will be
terminated and the appliance will go to lockout).
The appliance monitors the setting of the heating
potentiometer against the temperature of the
primary thermistor, and increases or decreases
current to the modulating coil, this in turn adjusts
the burner pressure, thus enabling the
temperature to be maintained to within a few
degrees (see section 5.10). When the temperature
of the primary thermistor exceeds the setting of
the heating potentiometer, ignition will be
terminated and the appliance will anti-cycle for
three minutes (timer delay). When a new ignition
sequence begins the output of the appliance is
set at minimum for two minutes.
NOTE
Any demand for hot water has the priority.
If there is a demand for hot water whilst the
appliance is anti-cycling, the timing will be can-
celled once the demand for hot water has been
satisfied.
7.5
FROST PROTECTION MODE
The built-in frost protection system will operate
the appliance in the OFF, HOT WATER ONLY
MODE, AND HEATING AND HOT WATER
MODE. Should the temperature of the appliance
fall to 7 ºC. the pump will run for fifteen minutes, this
will be repeated every two hours. Should the
temperature rise above 10 ºC. the fifteen minutes
will be cancelled. Should the temperature fall below
5 ºC. the boiler will fire at minimum output until the
temperature of the appliance exceeds 30 ºC.
NOTE
If the appliance is at lockout the frost protection
mode is disabled.
Although the frost protection mode is active even
when the appliance is switched off. The electrical
supply to the appliance must be maintained for it
to function.
Any demand for hot water or heating will reset
any frost protection settings.
7.6
BURNER PRESSURE SETTINGS
Burner pressure settings should be checked and/
or adjusted whenever the appliance is being
serviced, commissioned, or the gas valve/control
PCB have been replaced.
The procedure for setting or adjusting must be
carried out in the following order:
●
set the maximum DHW gas pressure
●
set the minimum DHW gas pressure
●
set the maximum heating gas pressure
●
set the minimum heating gas pressure.
