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Siemens Building Technologies
Basic Documentation RVL471
CE1P2524E
HVAC Products
10 Function block "Space heating"
23.10.2002
2522
Z
1
1
The setting is to be made on operating lines 14 and 15.
Operating line
Setpoint
14
TV1, current flow temperature setpoint at an outside temperature of
15 °C
15
TV2, current flow temperature setpoint at an outside temperature of
–5 °C
The type of setting is to be entered on operating line 73.
Operating line
73
Bar
Operating line 14
Operating line 15
0
Acting
No action
No action
1
No action
Acting
Acting
2
No action
Display function only,
adjustment only via LPB
Display function only,
adjustment only via LPB
10.6.3 Deflection
The heat losses of a building are proportional to the difference between room tem-
perature and outside temperature. By contrast, the heat output of radiators does not
increase proportionally when the difference between radiator and room temperature
increases. For this reason, the radiators' heat exchanger characteristic is deflected. The
heating curve's deflection takes these characteristics into consideration.
In the range of small slopes (e.g. with underfloor heating systems), the heating curve is
practically linear – due to the small flow temperature range – and therefore corresponds
to the characteristic of low temperature heating systems.
The slope ”s” is determined according to the following formula:
T
Vw(
−
5)
– T
Vw(+15)
s =
20 K
s
Heating curve slope
T
Vw(
−
5)
Flow temperature setpoint at an outside temperature of
−
5 °C
T
Vw(+15)
Flow temperature setpoint at an outside temperature of +15 °C
On the controller, the heating curve is shown as a straight line. This straight line corre-
sponds exactly to the deflected heating curve, because the non-linear outside tem-
perature scale corresponds to the deflection.
The heating curve is valid for a room temperature setpoint of 20 °C.
Setting with the bar
Setting on the operating
lines
Selection of setting
