Energy Balance Control; Flow Temperature Setpoint Control; Fixed Value Controlling - Vaillant geoTHERM VWS 220/2 Instrucciones De Operación

The heating engineer will set up a control diagram appro-
priate to your heating installation in the controller of the
heat pump. Depending on which control diagram is set up,
the controller performs either energy balance control or
flow temperature setpoint control. In the case of a system
without a heating water buffer tank, the controller performs
energy balance control. In the case of a system with a heat-
ing water buffer tank, the controller performs flow tempera-
ture setpoint control.
3.3.1

Energy balance control

Energy balance control is only applicable to heating installa-
tions without a heating water buffer tank.
For economical and fault-free operation of a heat pump, it
is important to regiment the starting of the compressor.
The start-up of the compressor is the point at which the
highest loading occurs. Using the energy balance control, it
is possible to minimise the number of heat pump start-ups
without having to forgo the convenience of a comfortable
room environment.
As with other weather-controlled heating controllers, the
controller determines a flow temperature setpoint for the
heating water by capturing the outside temperature by
means of a heating curve. The energy balance calculation is
made on the basis of this flow temperature setpoint and the
current flow temperature - the difference per minute is
measured and totalised:
The heat pump starts up at a defined heat deficit and only
switches off again when the supplied heat is equal to the
heat deficit.
The larger the heating engineer presets the negative
numerical value for the compressor start-up, the longer the
periods for which the compressor is kept running or at
standstill.

3.3.2 Flow temperature setpoint control

Flow temperature setpoint control is only applicable to
heating installations with a heating water buffer tank.
As with other weather-controlled heating controllers, the
controller determines a flow temperature setpoint by cap-
turing the outside temperature by means of a heating
curve. The heating water buffer tank is controlled based on
this flow temperature setpoint.
The heat pump heats when the temperature of the VF1
buffer tank head temperature sensor is lower than the flow
temperature setpoint. It heats until the temperature meas-
ured by the RF1 sensor at the base of the buffer tank has
reached the flow temperature setpoint plus 2 K.
A temperature difference of 2 K (Kelvin = unit of tempera-
ture), for example, corresponds to a temperature difference
of 2 °C.
When connected to a DHW cylinder heating circuit, the
buffer tank is also heated when the temperature of the VF1
Operating instructions geoTHERM 0020051578_03
Unit function and design
head temperature sensor is less than 2 K higher than the
flow temperature setpoint (premature reheating).
With heating installations of this type, the first task of the
heating water buffer cylinder is to compensate any heat
deficit. Downstream, the heat pump compensates the heat
deficit of the heating water in the buffer cylinder. This pre-
vents the frequent start-up of the compressor due to the
presence of the highest loading (¬ section 3.3.1). The com-
pensation takes place as soon as this occurs, regardless of
the increased heat deficit, over a specific time interval.

3.3.3 Fixed value controlling

The controller allows a fixed flow temperature setpoint to
be set. This control is only set temporarily and is used, for
example, for the manually adjustable „Floor drying" func-
tion.
The controller regulates the flow temperature setpoint of
the heating mode at a set value, regardless of the outside
temperature. This regulation results in the frequent start-up
of the compressor and is energy-intensive. It is set up by
the heating engineer.
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