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Building Technologies
Boiler Sequence Controller RMK770
CE1P3132en
HVAC Products
6 Boiler sequence management
23.04.2009
T
T
T
TMnRt
TMnFl
T
1
2
m
2
.
m
1
31
32
S
58
T
T
T
TMnRt
TMnFl
T
1
2
m
2
.
m
1
313
2S
5
9
Startup and part load operation (m
1
< m
2
)
Setback operation (m
2
= 0)
Usually, the main flow temperature TMnFl is a mixture of heating circuit return tempera-
ture and boiler temperature. The level of mixing depends on the water volumes on the
boiler and consumer side.
If no more water can circulate on the consumer side, it can well be that the temperature
acquired by the return temperature sensor TMnRt is higher than the main flow tempera-
ture TMnFl since there is no circulation at that sensor. To ensure that in such cases
there is no demand for unnecessarily high boiler temperatures, it is practical to use the
main return temperature as an additional controlled variable. The controller makes
automatically a maximum selection of the 2 sensors.
With plant types K1.x, K2.x and K3.x, a main pump is preconfigured since these plant
types do not have their own boiler pump. Basically, a main pump can be configured for
each plant type (
… > Outputs… > Main pump
). If, in addition, main pump B is configured,
the main pump is automatically set as a twin pump.
The main pump always operates when there is demand for heat.
If sustained mode is required for the boiler sequence,
… > Settings > Boiler sequence
manager > Sustained mode
can be used to parameterize whether the main pump shall also
operate in sustained mode.
For types of plant without individual maintained boiler return temperature, a common
maintained boiler return temperature can be delivered. This is activated by assigning a
terminal (
… > Outputs > Maint boiler return temp 3-pos
or
Maint boiler return temp mod
). In
addition, a return sensor for the maintained boiler return temperature must be config-
ured (
…> Inputs > MBRT return sensor
).
If a frost protection function is required due to the return on the consumer side, a
separate return sensor must be configured on the consumer side (
… > Inputs… Consumer
return sensor
).
In addition to fault supervision of the main pump and supervision of the main flow
temperature sensor, 3 binary fault inputs are provided for fault supervision of the boiler
sequence. These are freely configurable.
Heat requests from other devices can be accepted via bus. In addition, 3 binary inputs
and 1 analog input are available for indicating heat requests.
Main flow and main return
temperature sensor
Main pump
Common maintained
boiler return temperature
Return sensor on the
consumer side
Fault supervision
Heat request
