Heating Curve Adjustments - Viessmann VITODENS 200-W Service Instructions Manual

Vitodens 200-W B2HA 19, 28, 35 Service
Heating Curve Adjustment
The heating curves represent the relationship between
the outdoor temperature and the boiler water or supply
temperature.
Put simply: The lower the outdoor temperature, the
higher the boiler water or supply temperature.
In turn, the room temperature is dependent on the boiler
water or supply temperature.
If a different room temperature is set, the curves are
shifted parallel to the desired room temperature axis.
The control unit regulates the boiler water temperature
(= supply temperature of heating circuit without mixing
valve) and the supply temperature of the heating circuit
with mixing valve (in conjunction with the accessory
kit for a heating circuit with mixing valve) according to
the outdoor temperature. The boiler water temperature
is automatically raised by 0 to 72 F / 0 to 40 K higher
than the currently required set supply temperature (in the
factory default setting the differential temperature is
14.4 F / 8 K). See coding address "9F" in General Group.
Room
set-point
temperature
Outdoor temperature
Outdoor Reset Programming Unit
The supply temperature that is required to achieve a given
room temperature depends on the heating system and
the thermal insulation of the building that is being heated.
The adjustment of the two heating curves is used to
match the boiler water temperature and the supply
temperature to these conditions. The boiler water
temperature is limited upwards by the fixed high limit
and the temperature set for the electronic high limit.
The supply temperature cannot rise above the boiler water
temperature.
Factory settings:
H slope = 1.4
H shift = 0
Note: If the heating system includes heating circuits with
mixing valves, then the flow temperature of the
heating circuit without mixing valve is higher by a
selected differential (8 K in the factory setting) than
the flow temperature of the heating circuits with
mixing valves. The differential temperature can be
changed at coding address 9F.
A Low-temperature heating system,
e.g. radiant floor heating, 0.2 - 0.7
B Medium-temperature heating system, e.g. cast iron
radiation, panel radiant floor heating, 0.7 - 1.2
C High-temperature heating system,
e.g. fintube radiation, fan coils,1.2 - 1.5
35