Bosch Thermotechnology MBC 2, Руководство пользователя

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Description
MBC 2 – 6 720 810 583 (2014/02) 18
2.2.2 Switching method
Figure 4 depicts in diagrammatic form the switching method for the
MBC 2 and the associated boiler process. This figure is based on 2
identical boilers without hot water supply and with a set waiting time of
0 minutes for switching on the second boiler.
The figure is also based on a modulating weather-dependent regulator.
The switching method for a modulating room temperature regulator is
more or less the same.
Fig. 4 Switching method of the MBC 2 in combination with a
modulating weather-dependent regulator
[1] output of second boiler
[2] output of first boiler
[3] demand for heat ModuLine iRT thermostat
[t] time
Line A At the moment that there is no demand for heat, neither of the
boilers will be in operation.
Line B In the event of a minimum demand for heat from the ModuLine
(
i
RT) thermostat, the first boiler will be switched on at mini-
mum output and the second boiler will not come into operation.
Line C As the demand for heat from the ModuLine (
i
RT) thermostat
increases to 50%, the first boiler will modulate upwards from
minimum to maximum output and the second boiler will not
come into operation.
Line D As the demand for heat from ModuLine (
i
RT) thermostat
increases from 50%, the second boiler will be switched on at
minimum output in addition to the first boiler, and at the same
time the first boiler will modulate back so that the supplied
output from the first boiler plus the supplied output from the
second boiler is equal to the required output of 50%.
Line E As the demand for heat from the ModuLine (
i
RT) thermostat
increases from 50% to maximum, the first boiler will modulate
upwards to maximum output, and then the second boiler will
modulate upwards to maximum output.
Line F/H In the event of a maximum demand for heat from the ModuLine
(
i
RT) thermostat, both the first boiler and the second boiler will
supply maximum output.
Line G/I In the event of decreasing demand for heat from the ModuLine
(
i
RT) thermostat from maximum to 50%, first the second boiler
will modulate back downwards to minimum output, and then
the first boiler will modulate back from maximum so that the
output supplied by the first boiler plus the output supplied by
the second boiler is equal to the required output of 50%.
LineJ In the event of a demand for heat from the ModuLine (
i
RT) ther-
mostat of 50%, the second boiler will be switched off and, at
the same time, the first boiler will modulate upwards to maxi-
mum output.
Line K As the demand for heat from the ModuLine (
i
RT) thermostat
decreases from 50% to minimum, the first boiler will modulate
back to minimum output.
Line L In the event of a minimum demand for heat, the first boiler will
continue to burn at minimum output.
Line M Both boilers will switch off if there is no demand for heat.
2.2.3 Control of system pump
The system pump is switched on if one of the following conditions is met:
• The MBC 2 has just been connected to the mains electricity supply;
• The desired output exceeds 0 kW;
• The system pump has not been switched on in the previous 24 hours;
• Frost protection supply temperature is active;
• Frost protection outside temperature is active.
As soon as none of the above conditions are being met any longer, the
system pump will switch off after 5 minutes.
2.2.4 Frost protection - general
The MBC 2 has two methods of frost protection, namely:
• frost protection at outside temperature;
• frost protection at supply temperature.
Frost protection at outside temperature
Frost protection at outside temperature is possible both with a
modulating weather-dependent regulator and with a modulating room
temperature regulator on the condition that the outside temperature
sensor is connected to the MBC 2.
The frost protection based on outside temperature becomes active
when the outside temperature decreases to below 3 °C, and it is
deactivated when the outside temperature exceeds 5 °C.
When the frost protection is active, there is a demand for heat for which
the required supply temperature is 15 °C.
Frost protection at system temperature
Frost protection at system temperature applies to both a modulating
weather-dependent regulator and to a modulating room temperature
regulator.
The frost protection at system temperature becomes active as the
system temperature is lower than 3 °C, and is deactivated again when
the system temperature exceeds 15 °C.
When the frost temperature is active, there is a demand for heat for
which the required system temperature is 15 °C.
6 720 810 583-04.1TD
min.
min.
max.
max.
min.
max.
A B C D E F G H I J K L M
50%
1
2
3
[t]
CAUTION:
In spite of the MBC 2 frost protection, the equipment
cannot be guaranteed to be free of frost in all
circumstances.