Strebel S-CB+ Series, Installation Operating & Maintenance Manual

Page: 91 / 125

S-CB
+
Boiler Range Manual
91
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 water flow (but filled with water!) will
cause the so called
“boiling noises”. Check during this “service function” operation also the flow and return tem-
peratures
of the boiler by pressing the [◄] button once. The temperature difference of the flow and return must be
between 13°C and 25°C at high fire. This temperature difference indicates that there is a sufficient water flow over
the boiler; this water flow protects the heat exchanger against 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 (T1 and T2). When the temperature difference (delta T) between the 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, as set in
the parameters.
Display message
d T B l o c k
9 9 9 , 5 h r s
Reason Temperature difference T1-T2 has exceeded the blocking value.
When the T1-T2 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 T1-T2 has exceeded the blocking value more
than three 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 ex-
changer.
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.