Siemens Building Technologies
Basic Documentation RVL470
CE1P2522E / 30.03.2000
Landis & Staefa Division
Function block "Space heating"
25/68
8.5.2. Room temperature influence
The room temperature is included in the control process, in which case a room tem-
perature sensor is required (sensor or room unit).
The gain factor for the room temperature influence can be adjusted. This indicates to
what extent deviations of the actual room temperature from the setpoint have an impact
on flow temperature control:
0
= room temperature deviations have no impact on the generation of the setpoint
20 = room temperature deviations have a maximum impact on the generation of the
setpoint
The reduction of the room temperature setpoint
∆
T
Rw
is calculated according to the fol-
lowing formula:
VF
∆
T
Rw
[K] =
–––––
*
( T
Rw
– T
Rx
)
2
T
Rw
T
R
T
Rw
The change of the flow temperature setpoint resulting from the change of the room tem-
perature setpoint is calculated as follows:
∆
T
Vw
[K] =
∆
T
Rw
*
( 1 + s )
where:
s
Heating curve slope
T
Rw
Room temperature setpoint
∆
T
Rw
Change of room temperature setpoint
-
∆
T
Rw
Reduction of room temperature setpoint
+
∆
T
Rw
Increase of room temperature setpoint
T
Rx
Actual value of room temperature
∆
T
R
Room temperature deviation (T
Rw
–
T
Rx
)
∆
T
Vw
Change of flow temperature setpoint
VF
Gain factor
8.6. Heating curve
8.6.1. Purpose
With the space heating systems (plant types 1, 2 and 3), flow temperature control is
always weather-compensated. Assignment of the flow temperature setpoint to the pre-
vailing outside temperature is made via the heating curve.
8.6.2. Basic setting
The basic setting of the heating curve is made with the little bar or via two operating
lines (also refer to section "19.1.2. Analog operating elements").
The following settings are required:
•
The flow temperature setpoint at –5 °C outside temperature
•
The flow temperature setpoint at +15 °C outside temperature
The basic setting during commissioning is made according to the planning documenta-
tion or in agreement with local practices.
