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Siemens Heating and D.h.w. Controller RVL481 CE1P2541en
Building Technologies 12 Function block "Boiler" 20.05.2008
12 Function block "Boiler"
Function block "Boiler" acts as a 2-position controller and is used for direct burner con-
trol. Depending on the type of plant, it acts as a:
• boiler temperature controller for weather-compensated control of a space heating
system (plant type 2–x)
• boiler temperature controller for demand-compensated control of a main flow (plant
type 5–x)
12.1 Operating lines
Line Function, parameter Factory setting (range) Unit
91 Operating mode of the boiler 0 (0 / 1)
92 Maximum limitation of the boiler temperature 95 (25…140) °C
93 Minimum limitation of the boiler temperature 10 (5…140) °C
94 Switching differential of the boiler 6 (1…20) °C
95 Minimum limitation of the burner running time 4 (0…10) min
96 Release limit for second burner stage 50 (0…500) °C×min
97 Reset limit for second burner stage 10 (0…500) °C×min
98 Waiting time for second burner stage 20 (0…40) min
99 Operating mode pump M1 1 (0 / 1)
12.2 Operating mode
The boiler’s operating mode for situations when there is no demand for heat (e.g. due
to the ECO function),can be selected: 3 operating modes are available:
• With manual shutdown: The boiler will be shut down when there is no demand for heat
and protection mode
is selected (setting 0 on operating line 91)
• With automatic shutdown: The boiler will be shut down when there is no demand for
heat, irrespective of the selected operating mode (setting 1 on operating line 91)
Boiler operating modes, when there is no demand for heat:
Boiler operating mode
Controller's operating
mode
with manual shutdown with automatic shutdown
Protection Boiler OFF Boiler OFF
AUTO Boiler at minimum limit value Boiler OFF
REDUCED Boiler at minimum limit value Boiler OFF
NORMAL Boiler at minimum limit value Boiler OFF
With plant types 5–x, it is not possible to select all operating modes (refer to section
“3.7 Plant type and operating mode").
When there is demand for heat, the boiler always supplies heat, which means that the
boiler's operating mode in that case is always ON.
12.3 Limitations
12.3.1 Maximum limitation of the boiler temperature
For maximum limitation of the boiler temperature, the maximum limit value can be ad-
justed. The switch-off point cannot exceed the maximum limit value. The switch-on
point will then be lower by the amount of the set switching differential.
If the return temperature is limited, the display shows
.
This maximum limitation cannot be used as a safety function; for that purpose, thermo-
stats, thermal reset limit thermostats, etc., must be used.
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