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By pressing the [SERVICE] button of the boiler, the boiler can be started without a heating demand. The boiler will
start to fire and also the pump will start to run. Firing of the boiler without a water flow (but filled with water!) will cause
the so call
ed “boiling noises”. Check during this “service function” operation also the flow and return temperatures of
the boiler by pressing the [◄] button once. The temperature difference of the flow and return must be at least 13°C
and maximum 25°C. This temperature difference indicates that there is a (enough) water flow over the boiler; this
water flow prevents the heat exchanger of possible damage caused by a thermal overload.
Another safety feature of the boiler, to make sure that there is enough water flow over the boiler, is the monitoring of
the flow and return temperatures (T2 and T1). When the temperature difference (delta T) between flow and return
exceeds a certain (set) value, the following warning messages will be shown in the display.
Display message
T 2 - T 1
h i g h
9 9 9 , 5
h r s
Reason
Temperature difference T2-T1 has exceeded the blocking value which has been set in the param-
eters.
Display message
d T B l o c k
9 9 9 , 5
h r s
Reason
Temperature difference between flow and return exceeds the blocking value but not the lock out
value.
When this delta T value exceeds the lock-out setting, the boiler will switch off and the following lock out code will be
shown at the display.
Display message
F16
F l o w R e t u r n
d t
f a u l t
p u m p
o n
9 9 9 , 5
h r s
Reason
Temperature difference between flow and return exceeds limitation value or ‘dT Block’or ‘Delta
direct Block’ has occurred 3 times.
When these messages appear and/or the boiler will lock out, it means that there is not enough flow over the boiler.
In this case check the functioning of the pump.
The boiler has no built-in water-flow switch. If there is the possible risk of a water-flow blockage of the (external)
heating system, the following pre-cautions can be taken to ensure a water flow over the boiler:
•
Separate the boiler circuit from the (external) heating circuit by using a low loss header or plate heat
exchanger.
•
When the boiler is not equipped with an internal (built in) water pressure switch, install a water pressure
switch externally, in series with the room thermostat.
During and after the commissioning of the boiler, the operation of the boiler pump must be checked, before leaving
the installation room.
NOTICE: Always check the running of the pump before firing the boiler.
