Starting Central Heating - Viessmann VITOTRONIC 200 Service Instructions Manual

Function description
Heating circuits/cooling circuits
The heat pump control unit switches automatically
between central heating and central cooling, subject to
the adjusted outside temperature ("Interval for long
term average outside temperature 7002").
Fixed hystereses are programmed to prevent brief fluc-
tuations around these temperature limits from causing
constant changeover between central heating and cen-
tral cooling.

Starting central heating

If all of the following conditions are met, central heat-
ing starts:
■ The adjusted outside temperature drops below the
heating limit: See page 51.
■ The "Heating and DHW" or "Heating/cooling and
DHW" operating program is switched on.
A time phase is active in "Time program heating"
■
or "Time proghtg/cooling" for the respective heat-
ing/cooling circuit.
■ System with heating water buffer cylinder: A time
phase is active in "Time prog buffer cyl".
■ / : System with heating water/coolant buffer
cylinder (system configuration
A time phase is active in "Time prog buffer cyl".
"Buffer cyl operating mode 721F" is set to "0".
"Vitotronic 200" operating instructions
Switching off central heating
In the case of weather-compensated control, central
heating is switched off under the following conditions:
■ One of the conditions for starting central heating is
no longer met: See chapter on "Starting central heat-
ing".
or
The adjusted outside temperature exceeds the heat-
■
ing limit by 2 K.
Starting central cooling
If all of the following conditions are met, central cooling
starts:
The adjusted outside temperature exceeds the cool-
■
ing limit: See page 51.
The "Heating/cooling and DHW" operating pro-
■
gram is activated.
■ A time phase with the operating status "Standard"
or "Fixd value" is active in "Time proghtg/cooling"
for the relevant heating/cooling circuit.
52
(cont.)
on page 49):
2
Note
■ For frost protection, it is safer to also take account of
short term fluctuations. Therefore, to start and stop
the frost protection function, the heat pump control
unit uses the short term average outside tempera-
ture.
If a room temperature sensor is installed, a short
■
term average is also available for the room tempera-
ture. The heat pump control unit uses this value for
room temperature hook-up with weather-compensa-
ted control or for room temperature-dependent con-
trol ("Room temperature control 2005").
Additional condition for weather-compensated con-
trol:
■ The flow temperature is below the set flow tempera-
ture: See page 50.
Additional condition for room temperature-dependent
control:
The room temperature drops below the set room
■
temperature: See page 51.
Note
If central heating is activated, the heating circuit pump
runs constantly. For heating/cooling circuits without
mixer which are connected directly to the heat pump,
the secondary pump is on constantly.
For room temperature-dependent control or weather-
compensated control with room temperature hook-
up, central heating is switched off under the following
conditions:
■ One of the conditions for starting central heating is
no longer met: See chapter on "Starting central heat-
ing".
or
The room temperature exceeds the set room temper-
■
ature by 5 K.
■ / : "Enable active cooling 71FE" is set to
"1".
/ : System with heating water/coolant buffer
■
cylinder (system configuration
A time phase is active in "Time prog buffer cyl".
"Buffer cyl operating mode 721F" is set to "1".
"Vitotronic 200" operating instructions
2 on page 49):