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2.3
Notes on commissioning
DANGER: Risk to life and of system damage through
excessively high temperatures.
All parts directly or indirectly subject to high
temperatures must be designed for use at such
temperatures.
B Ensure that wiring and other lines are routed at a safe
distance from hot boiler parts.
B Route wiring and other lines, in the wiring ducts
provided or above the boiler insulation.
B Before switching the control unit on, check that its manual switches
and those on the function modules are set to AUT.
B Enter the settings made during commissioning and the allocation of
the heating circuits into the commissioning report in the operating
instructions of the control unit.
B Switch on the control unit first and then the boiler.
B To shut down, switch off the boiler first and then the control unit.
B Ensure that there is sufficient heat load, otherwise the boiler will
switch off and generate a fault condition.
2.4
Cleaning the control unit
B Only clean the control unit with a damp cloth.
2.5
Product description
The digital CFB 840 control unit is suitable for regulating a floor-standing
oil/gas-fired boiler with single stage, two-stage or modulating burner.
As standard, the unit includes the DHW heating (cylinder system) and
heating circuit control (one heating circuit without actuator) functions. It
can be expanded by adding up to two function modules to suit the
requirements of the heating system.
2.6
Scope of supply
Included in the standard delivery:
• Digital CFB 840 control unit with programming unit
• FA outside temperature sensor
• Boiler water temperature sensor FK
2.7
Technical data
2.7.1 Controller CFB 840
Dimensions B/H/L
Operating voltage (at 50 Hz ±4 %)
Power consumption
Control unit fuse
Maximum switching current
• Burner output
• Boiler or heating circuit pump
output
Boiler circuit actuator control
Servomotor runtime, burner
modulating
Type of controller - burner and
heating circuit actuator
Ambient temperatures
• Operation
• Transport
Table 2 Specification - CFB 840 control unit
CFB 840
Unit
CFB 840
mm
460/240/230
V
230 ± 10 %
VA
5
A
10
8
A
5
V
230
sec
120
(adjustable from 5 to
60)
Three-point stepper
controller (PI
characteristics)
+5...+50
°C
–20...+55
smallest
lower fault
display value
Sensor
limit in °C
in °C
FA
–50
–40
FK
< –5
0
FB
< –5
0
Table 3 Sensor measuring range
2.7.2 FM442/CMM 920 function module
Operating voltage (at 50 Hz ± 4 %)
Power consumption
Maximum switching current - heating
circuit circulation pump output
Heating circuit actuator control
Servomotor runtime
Type of controller
Table 4 Technical data for FM442/CMM 920 function module
lower
smallest
fault
display
limit
value
Sensor
in °C
in °C
FV1 flow temp. HC
< –5
0
on left
FB flow temp. HC
< –5
0
on right
Table 5 Sensor measuring range
3
Setting instructions
3.1
Setting instructions and replacement instructions for
high limit safety cut-out (STB)
3.1.1 Setting and installation of the high limit safety cut-out
DANGER: Risk to life from electric shock!
B Before opening the control unit, isolate all poles of the
control unit and secure against unauthorised re-
connection.
To be able to set the temperatures, the high limit safety cut-out (STB)
must be removed from the control unit housing.
B Undo screws [1].
B Remove cover [2].
B Remove protective cap [3].
B Undo the screw connection.
B Remove the STB with its assembly plate and make the adjustments
(
chapter 3.1.2).
Setting instructions | 5
highest
display value
upper fault
in °C
limit in °C
50
> 70
> 108
> 125
99
> 125
Unit
Value
V
230 ± 10 %
VA
2
A
5
V
230
sec
120 (adjustable
10 – 600)
–
Three-point stepper
controller (PI
characteristics)
highest
display
value
upper fault limit
in °C
in °C
99
125
99
125
6 720 802 836 (2012/05)
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