Dhw Heating - Viessmann VITOTRONIC 200 Service Instructions Manual

Function description
Booster heaters
(cont.)
Note
The fault message "AB Instant.htg wtr heater" is dis-
played if the instantaneous heating water heater is
called for and the differential between flow and return
temperatures in the secondary circuit does not
increase by at least 1 K within 24 h.
Central heating
Enabling required
Parameter
"Enable instantaneous heating wa-
ter heater 7900"
"Enable instant. heating water
heater for central heating 7902"
!
Please note
After the value "1" has been set for "Enable
instantaneous heating water heater 7900",
the prompt "Secondary circuit filled?" auto-
matically appears. If this prompt is responded to
with "No", the instantaneous heating water
heater will not be enabled. Set "Enable instan-
taneous heating water heater 7900" to "2".
Fill the secondary circuit. Confirm prompt "Sec-
ondary circuit filled?" with "Yes".
The instantaneous heating water heater can only be
started for central heating if all of the following condi-
tions are met:
Operation of the instantaneous heating water heater
■
is enabled as per "Time prog elec heater".
"Vitotronic 200" operating instructions
■ Adjusted outside temperature falls below "Dual
mode temp instant. heating water heater 790B".
■ The secondary circuit flow temperature under-
shoots the set value by 2 K.
Note
Vitocal 300-A, type AWO 302.B:
The secondary circuit return temperature under-
shoots the set value by 2 K.

DHW heating

DHW heating by the heat pump
In the delivered condition, DHW heating by the heat
pump takes priority over central heating/cooling.
This setting can be changed by a heat pump installer
certified by Viessmann.
40
"Start threshold 730E" exceeded.
■
■ "Start delay instantaneous heating water heater
7905" e.g. after changing the operating status
expired.
Subject to how much the "Start threshold 730E" has
been exceeded, different stages of the instantaneous
heating water heater are switched on.
Note
As frost protection for the heating circuits or the buffer
Setting
cylinder, the instantaneous heating water heater will
"1"
also be switched on if none of the above criteria is
met.
"1"
Switching off the instantaneous heating water
heater
■ For direct heating circuits (without buffer cylinder):
Under the following conditions, the heat pump con-
trol unit switches off the individual stages of the
instantaneous heating water heater in succession:
The secondary circuit flow temperature exceeds the
set flow temperature.
Note
Vitocal 300-A, type AWO 302.B:
The secondary circuit return temperature exceeds
the set return temperature.
Heating circuits with mixer (with buffer cylinder):
■
If the return temperature in the secondary circuit
exceeds the set buffer temperature, the heat pump
control unit switches the instantaneous heating water
heater off.
DHW reheating
See chapter "DHW reheating with booster heaters" on
page 42.
If DHW priority has been set, and there is a simultane-
ous heat demand for heating circuits and the DHW cyl-
inder, the DHW cylinder is heated only for the duration
of "Max. runtime DHW heating in heating mode
6011". If the heat demand from the DHW cylinder is
then still active, heating circuits will only be supplied
for the duration of "Max. interruption of DHW heat-
ing for central heating 6012".