Boiler control and control system
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6 720 807 794 (2013/04)
UNIMAT
Fig. 25 Frequency analysis of noise at the chimney outlet,
subject to the boiler output
f
Frequency
L
Sound pressure level
The following comments apply to the values specified:
• Sound pressure level measured in accordance with
DIN-EN 60804, DIN-EN 60651 and DIN 45635
• Frequency assessment curve A to DIN-EN 60561
• Flue system routed with favourable flow
characteristics
• Suitable anti-vibration mounts installed in the boiler
system
7
Boiler control and control system
A boiler control is required to operate the UNIMAT UT-L
boilers.
Depending on the requirements and structure of the
heating system, the following boiler controls are
available:
• CFB 810 control unit
• CFB 9xx control unit
• BCO boiler control incl. control panel and safety chain
The Bosch CFB control units are of modular design. This
enables the selection of well-matching and economical
units for all applications and stages of development in
the proposed heating system. An additional control unit
is required to provide the electrical connection to the
burner for the burner power contactors controlled by
the control units.
7.1
CFB 810 control unit with CME 930
auxiliary module
Brief description of possible applications
The CFB 810 analogue control unit is suitable for
controlling a floor standing oil or gas boiler with
constant boiler temperature, without operating
conditions, or in conjunction with an overriding control
system (e.g. DDC/GLT). The CFB 810 analogue control
unit can control single stage, 2-stage or modulating
burners.
The CME 930 auxiliary module is only intended for use in
the CFB 810 analogue control unit and is suitable for
safeguarding boiler operating conditions in
conventionally operated boilers. Only one can be fitted
in each control unit.
Boiler safety functions
By actuating a boiler circuit pump and an actuator (3-
way mixer), the CME 930 auxiliary module safeguards
the required boiler operating conditions for boilers with
a minimum return temperature.
In conjunction with the appropriate plumbing
configuration, compliance with the required boiler
operating conditions is guaranteed. When the boiler
circuit is in automatic mode, appropriate adjustments
should be made on the CME 930 auxiliary module PCB
(service level). The CME 930 can also be used to
hydraulically shut off lag boilers in multi boiler systems,
by actuating the actuator.
Burner control
The CME 930 auxiliary module controls single stage, 2-
stage, modulating or 2 × single stage burners.
There are two ways to control the burner which can be
adjusted via manual mode level:
• Direct, potential-free enabling of stages in an
overriding control system (AUT), e.g. DDC/GLT
or
• Enabling of all burner stages by the control unit via
the hand or full load symbol, in which case burner
modulation may also be manually adjustable
Return temperature control
With return temperature control mode, the boiler is
operated with a fixed figure for the return temperature.
This return temperature can be set on the PCB (service
level) of the module with potentiometer P1 to 50–60 °C.
Return temperature control is constantly active:
• Via a separate actuator (3-way mixer) and with bypass
pump (without hydraulic separation)
• Via a separate actuator (3-way mixer) with a boiler
circuit pump (with hydraulic separation via low loss
header)
The values specified are only a guide and
approximate values. They depend on the
fuel, burner manufacturer, burner
construction and design of the entire flue
system.
50
60
70
80
90
100
110
f [Hz]
L [dB (A)]
31,5
63
125
250
500
1000
2000
4000 8000
6 720 642 347-76.1il
> 15000 kW
≤
15000 kW
≤
10000 kW
≤
5000 kW
≤
2500 kW
According to the Energy Savings Order
(EnEV, para. 12), the CFB 810 control unit
must be operated in conjunction with an
automatic device for weather-compensated
or room temperature-dependent mode with
time programs.