Siemens Building Technologies
Basic Documentation RVL470
CE1P2522E / 30.03.2000
Landis & Staefa Division
Function block "Space heating"
19/68
T
A
(B9 or BUS)
25
22
B
0
2e
T
A
k
t
k
t
T
AD
T
AM
Generation of the composite and attenuated outside temperature
T
A
Actual outside temperature
T
AD
Attenuated outside temperature
T
AM
Composite outside temperature
kt
Building time constant
0
5
10
15
20
25
T
AD
T
AM
t
25
2
2
D1
7
T
A
T
A
Development of the actual, composite and attenuated outside temperature
T
A
Actual outside temperature
T
AD
Attenuated outside temperature
T
AM
Composite outside temperature
t
Time
8.2.2. Heating limits
Two heating limits can be set:
•
"ECO day" for NORMAL heating
•
"ECO night" for the lower temperature level; this may be REDUCED heating or OFF
(holidays / frost protection)
In both cases, the heating limit is the outside temperature at which the heating shall be
switched on and off. The switching differential is 1 °C.
8.2.3. Mode of operation
8.2.3.1. Switching the heating off
The heating will be switched off when one of the three following conditions is satisfied:
•
The actual outside temperature exceeds the current ECO heating limit
•
The composite outside temperature exceeds the current ECO heating limit
•
The attenuated outside temperature exceeds the "ECO day" heating limit
In all these cases, it is assumed that the amount of heat entering the building envelope
from outside or the amount of heat stored in the building structure will be sufficient to
maintain the required room temperature level.
When the ECO function has switched the heating off, the display shows
ECO
.
