Vaillant VRC 470 Installation Instructions Manual page 45

14 Glossary
Auto_Off
In the "Auto_Off mode" (Installer level), in Automatic
mode the control functions outside active time periods
can be specified separately for each heating circuit.
There are three control modes (frost protection, ECO,
set-back temp.) available for selection, which can be fur-
ther adapted through the use of the room temperature
control.
Circulation pump
When you turn on the hot water tap it can take a few
moments - depending upon the length of the pipe -
before hot water comes out. A circulation pump pumps
hot water through the hot water pipe. This ensures that
hot water is immediately available when you turn on the
tap. Periods can be set for the circulation pump.
DCF77 receiver
A DCF77 receiver receives a remote time signal from
sender DCF77 (D-Germany C-Long-wave transmitter
F-Frankfurt 77). The time signal sets the time on the
controller automatically and provides automatic switch-
ing between summer time and winter time. The DCF77
time signal is not available in all countries.
Flow temperature
See Heating flow temperature.
Frost protection delay time
By setting a frost protection delay time
(Installer level) the activation of the frost protection
function (outside temperature < 3 °C) can be delayed by
a certain period of time (1 - 12 hours).
The frost protection delay setting also works in the
"ECO" function in the "Auto_Off" mode (see location).
The frost-protection delay time starts when the outside
temperature drops below 3 °C.
Frost protection function
The frost protection function protects the heating sys-
tem and dwelling against frost damage. It remains active
in the operating mode "OFF".
The frost protection function monitors the outside tem-
perature. When the outside temperature drops below
3 °C, the heating pump is switched on for approx. 10 min.
and then off for 10 to 60 min. (depending on the outside
temperature). If the heating flow temperature is lower
than 13 °C, the boiler is switched on. The target room
temperature is regulated at 5 °C. If the outside tempera-
ture rises above 4 °C, the outside temperature monitor-
ing remains active while the heating pump and boiler
are switched off.
When the outside temperature drops below -20 °C, the
boiler is switched on. The target room temperature is
regulated at 5 °C.
Installation instructions VRC 470 0020116690_00
Heating circuit
A heating circuit is a closed circulation system of pipes
and heat consumers (e. g. radiators). The heated water
from the boiler flows into the heating circuit and returns
to the boiler as cooled water.
A heating installation usually has at least one heating
circuit. However additional heating circuits can be con-
nected, e.g. to supply several dwellings or additional
underfloor heating.
Heating curve
The heating curve represents the relationship between
external temperature and the flow temperature. The
selection of a heating curve allows you to influence the
flow temperature of the heating system and therefore
also the room temperature.
Fig. 14.1 shows the possible heating curves for a target
room temperature of 20 °C.
If, for example, heating curve 0.4 is selected, a flow tem-
perature of 40 °C is maintained at an outside tempera-
ture of -15 °C.
Flow temperature in °C
4.0 3.5 3.0 2.5
70
60
50
40
30
15 10 5
Fig. 14.1 Heating curve diagram
Flow temperature in °C
70
60
50
40
30
22
20
15 10
Axis a
18
Target
room temperature
Fig. 14.2 Parallel displacement of the heating curve
If heating curve 0.4 is selected and 21 °C rather than
20 °C is specified as the target room temperature, the
heating curve is displaced as shown in Fig. 14.2. The
heating curve is displaced according to the value of the
room target temperature along axis a which is angled at
45°, This means that when the outside temperature is
-15 °C, the control provides a flow temperature of 45 °C.
Glossary
Heat curves
1.2
2.0 1.8 1.5
0 -5 -10 -15
Outside temperature in °C
5 0 -5 -10 -15
Outside temperature in °C
14
1.0
0.8
0.6
0.4
0.2
0.1
-20
0.4
-20
45