Viessmann VITOTRONIC 200 Service Instructions Manual page 28

Function description
Heating circuits/cooling circuit
Fixed hystereses are programmed to
prevent brief fluctuations around these
limits from resulting in continual change-
over between central heating and central
cooling. Furthermore, the heat pump
control unit uses the long term aver-
age outside temperature for change-
over.
For frost protection, it is safer to also take
account of short term fluctuations.
Therefore, to start and stop the frost pro-
tection function, the heat pump control
unit uses the short term average out-
side temperature.
If a room temperature sensor is installed,
a short term average is also available for
the room temperature. The heat pump
control unit uses this value for room tem-
perature hook-up with weather-compen-
sated control or for room temperature-
dependent control.
Central heating/cooling stops if the room
temperature exceeds/falls below the
value "Standard room temperature
2000" by the set hysteresis.
Operating status for central heating/
cooling
Operating status "Standard"
Central heating/cooling is enabled with
the "Standard room temperature
2000".
Operating status "Reduced"
Central heating is enabled with the
"Reduced room temperature 2001".
Note
In this operating status central cooling is
not possible.
28
(cont.)
Operating status "Fixed value"
Central heating/cooling with "Max. flow
temperature heating circuit
200E"/"Min. flow temperature cooling
7103".
Operating status "OFF"
This operating status is enabled if no
other operating status has been selec-
ted.
Note
In this operating status central cooling is
not possible.
Central heating is activated if one of the
following criteria is met:
■ Short term average outside tempera-
ture falls below the frost protection
limit.
■ Room temperature falls below 5 °C
(Parameter "Remote control 2003"
set to "1").
■ System flow temperature falls below
5 °C.
For frost protection the heating circuit
pumps and the secondary pump are
started alongside the heat pump.
Heating in frost protection mode ends if
all the following criteria are met:
■ Short term average outside tempera-
ture exceeds the frost protection limit
by at least 2 K.
■ Room temperature exceeds 7 °C
(parameter "Remote control 2003"
set to "1").
■ System flow temperature exceeds
15 °C.