Control Unit For Weather-Responsive Operation - Viessmann Vitodens 200 Start-Up/Service Instructions

Vitodens 200 WB2 Service

Control Unit for Weather-Responsive Operation

Functional description
Space heating mode
The control unit calculates a boiler water setpoint
temperature based on the outdoor or room temperature
(where a room temperature dependent remote control is
connected) and on the slope/shift of the heating curve.
The computed boiler water setpoint temperature is
transmitted to the burner control unit.
From the boiler water setpoint and the actual temperature
the burner control calculates the degree of modulation
required, and regulates the burner accordingly.
The maximum operating boiler water temperature is
limited in the burner control unit:
to 167ºF / 75ºC by the electronic temperature control.
The maximum adjustable high limit of the boiler is 180ºF
/ 82ºC.
The fixed high limits of the safety chain interlock the
burner control unit at 210ºF/99ºC boiler water temperature.
Domestic hot water supply with Combi boiler
When the water flow switch detects that hot water is
being drawn (> 0.8 USG/3 ltr), the burner and circulating
pump switch on, and the 3-way solenoid valve switches
to domestic hot water production.
The burner modulates based on the required domestic hot
water outlet temperature and is limited by the electronic
limit thermostat on the boiler side. When the comfort
function is activated, the plate heat exchanger is kept at
a standby temperature of "108 ºF/42 ºC on" and "115ºF /
46ºC off".
With comfortrol menu driven progamming unit' (removable)
Domestic hot water supply
with gas-fired space heating boiler
Domestic hot water heating is activated when the tank
temperature is 4.5ºF/2.5ºC below the tank temperature
setpoint value.
The burner and the tank DHW pump are switched on.
In the factory default setting, the desired boiler water
temperature is set at 36ºF/20ºC above the tank
temperature setpoint value. When the actual tank
temperature rises 4.5ºF/2.5ºC above the tank temperature
setpoint value, the burner is switched off and the time
delay function of the tank DHW pump is activated.
Additional heating function (anti-legionnaire function)
for domestic hot water production
The additional heating function is activated when an
activation period of10 minutes is selected (e.g. 22.10
to 22.20 hrs).
This period must lie outside the switching times for normal
domestic hot water heating so that the signal is recognized
by the control unit. The temperature setpoint value for
additional heating is set in coding address "0A7".
Additional Information
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