B03 Start Threshold External Heat Source - Viessmann VITOTRONIC 200 Service Instructions Manual

Parameter group External heat source

7B03 Start threshold external heat source

To prevent the external heat generator starting immedi-
ately if the set flow temperature in the secondary cir-
cuit is not reached for a short time, the control unit
uses the output integral as start criteria. This output
integral is the integral from duration and extent of the
deviation of the set flow temperature to the actual
value. In fig 54, the output integral is the grey area
between the time line of the actual value and the hys-
teresis of the flow temperature secondary circuit.
C
Fig. 54
Set flow temperature, secondary circuit
A
Secondary circuit flow temperature actual value
B
Hysteresis, flow temperature secondary circuit
C
Output integral
D
7B04 Start delay external heat source
The external heat generator does not start within the
specified period following a change of the set flow tem-
perature in the secondary circuit. This may occur
for example during a change in operating status in the
time program ("Standard", "Reduced", "Fixd value")
or following a changeover between central heating and
DHW heating.
7B05 Min. flow temperature mixer external heat source ON
The following components for the hydraulic connection
of the external heat generator will only be switched
when the boiler water temperature has reached the set
value. This prevents cold heating water from entering
the system flow or the DHW cylinder.
■ Central heating: External heat generator mixer
opens.
DHW heating: Circulation pump for cylinder reheat-
■
ing starts.
7B06 Min. runtime external heat source
Following a demand, the control unit will not switch the
heat generator off within this time (demand signal at
terminals 222.3/222.4 'live').
212
A
D
B
t
!
!
!
Setting in K . min
Setting in min
!
If the boiler water temperature falls below the set
value, the mixer will be closed, and the circulation
pump for cylinder reheating is switched off.
≙
Setting 1 0.1 °C
Setting in min