Viessmann VITOCROSSAL 200 Type CM2 Technical Manual page 60

Control units
(cont.)
Functions
■ Weather-compensated control of the boiler water temperature
(= system flow temperature).
■ Electronic maximum and minimum flow temperature limit.
■ Demand-dependent heating circuit pump and burner shutdown (not
for burners in boilers with a lower boiler water temperature limit).
■ Adjustment of a variable heating limit.
■ Pump anti-seizing protection.
■ Integral diagnostic system.
■ Flue gas temperature monitoring in connection with flue gas tem-
perature sensor.
■ Maintenance display.
9
■ Adaptive cylinder temperature controller with priority control (heating
circuit pump off).
■ Auxiliary function for DHW heating (short term heating to a higher
temperature).
■ Control of solar DHW heating and central heating backup, plus
graphic illustration of the solar yield in conjunction with the solar
control module, type SM1.
■ Control of a cylinder loading system with mixer assembly (only as
an alternative to control of a constant return temperature raising
facility with regulated 3-way mixing valve).
■ External fault message facility can be connected.
■ With boiler protection functions subject to boiler version:
– ThermControl start-up system
– Flow rate reduction for downstream heating circuits
– Shunt pump control
– Control of a constant return temperature raising facility with regu-
lated 3-way mixing valve (only as an alternative to the control of a
cylinder loading system with mixer assembly)
■ Functions via external contacts:
– External operating program changeover
– External blocking
– External demand with set minimum boiler water temperature
– External changeover of stepped/modulating burners
■ Additional functions via extension EA1 (accessories):
– External demand through default set boiler water temperature via
0 to 10 V input
– Switching a feed pump to a substation
or
Signalling of reduced mode (reduction of the heating circuit pump
speed) via a potential-free output
– 3 digital inputs for the following functions:
External blocking with fault message input
Fault message input
Brief operation of the DHW circulation pump
■ Additional functions via extension AM1 (accessories):
– Control of up to two circulation pumps, if output sÖ is already
assigned at the control unit:
Circulation pump for flue gas/water heat exchanger
Circulation pump for neutralising system
Heating circuit pump
The requirements of EN 12831 for calculating the heat load are met.
To reduce the heat-up load, the reduced room temperature will be
raised in the case of low outside temperatures. The flow temperature
will be raised for a limited time to reduce the heat-up time after a set-
back phase.
According to the Energy Saving Ordinance [Germany], the tempera-
ture in each room must be individually controlled, for example by ther-
mostatic valves.
Control characteristics
■ P-characteristics with two-point output when using a burner with
multiple stages
PI characteristics with three-point output when using a modulating
burner
■ Temperature controller for limiting the boiler water temperature:
95 °C, adjustable to 100, 110 °C
■ Adjusting the high limit safety cut-out:
110 °C, adjustable to 100 °C
VIESMANN
60
■ Heating curve setting range:
– Slope: 0.2 to 3.5
– Level: −13 to 40 K
– Maximum limit of the flow temperature: 10 to 127 °C
– Minimum limit of the flow temperature: 1 to 127 °C
■ Setting range of the set DHW temperature:
10 to 60 °C, adjustable between 10 and 95 °C
Boiler coding card
For matching to the boiler (supplied with the boiler).
Time switch
Digital time switch (integrated into the programming unit)
■ Individual day and seven-day program, annual calendar
■ Automatic summer/wintertime changeover
■ Automatic function for DHW heating and DHW circulation pump
■ The default settings for time, day and standard switching times for
central heating, DHW heating and the DHW circulation pump are set
at factory
■ Switching times are individually programmable, i.e. up to four time
phases per day
Shortest switching interval: 10 min
Power reserve: 14 days
Setting the operating programs
Frost protection monitoring (see frost protection function) for the heat-
ing system is enabled in all operating programs.
The following operating programs can be selected:
■ Heating and DHW
■ Only DHW
■ Standby mode
Optional external operating program changeover.
Frost protection function
■ The frost protection function is switched on if the outside temperature
drops below approx. +1 °C, i.e. the heating circuit pump is switched
on and the boiler water is maintained at a lower temperature (see
chapter "Operating conditions with Vitotronic boiler control units").
■ "Standby mode":
The frost protection function is switched off if the outside temperature
rises above approx. +3 °C. This means that the heating circuit pump
and burner are switched off.
■ "Heating and DHW"
The frost protection function is switched off if the outside temperature
rises above approx. +3 °C. This means the heating circuit pump is
switched off and the lower boiler water temperature for the relevant
boiler is maintained if required (see chapter "Operating conditions
with Vitotronic boiler control units").
Summer mode
("DHW only")
The burner starts only when the DHW cylinder needs reheating (con-
trolled by the cylinder temperature controller).
The respective lower boiler water temperature of each boiler is main-
tained if required.
Heating curve setting (slope and level)
The Vitotronic controls the boiler water temperature (= system flow
temperature) in weather-compensated mode.
The flow temperature required to reach a specific room temperature
depends on the heating system and the thermal insulation of the build-
ing to be heated.
Adjusting the heating curve matches the boiler water temperature to
these conditions.
The upper boiler water temperature is limited by the temperature con-
troller and the electronic maximum limiter.
Gas condensing boilers