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Siemens Building Technologies
Basic Documentation RVL471
CE1P2524E
HVAC Products
10 Function block "Space heating"
23.10.2002
10 Function block "Space heating"
This function block performs the ECO function, the optimization functions with boost
heating and quick setback, as well as the room influence.
10.1 Operating lines
Line
Function, parameter
Unit
Factory
setting
Range
61
Heating limit for NORMAL heating (ECO day)
°C
17.0
--.- /
−
5...+25
62
Heating limit for REDUCED heating (ECO night)
°C
5.0
--.- / –5...+25
63
Building time constant
h
20
0...50
64
Quick setback
1
0 / 1
65
Room temperature source
A
0 / 1 / 2 / 3 / A
66
Type of optimization
0
0 / 1
67
Maximum heating up time
hh:mm
00:00
00:00...42:00
68
Maximum early shutdown
hh:mm
0:00
0:00...6:00
69
Maximum limitation of room temperature
°C
--.-
--.- / 0...35
70
Gain factor of room influence
4
0...20
71
Boost of room temperature setpoint
°C
5
0...20
72
Parallel displacement of the heating curve
°C
0.0
−
4.5...+4.5
73
Heating curve slope
0
0...2
10.2 ECO function
The ECO function controls space heating depending on demand. It gives consideration
to the progression of the room temperature depending on the type of building construc-
tion as the outside temperature varies. If the amount of heat stored in the house or
building is sufficient to maintain the room temperature setpoint currently required, the
ECO function will switch the heating off.
When using the ECO function, the heating system operates only, or consumes energy
only, when required.
10.2.1
Compensating variables and auxiliary variables
As compensating and auxiliary variables, the ECO function takes into account the de-
velopment of the outside temperature and the heat storage capacity of the building.
The following variables are taken into consideration:
•
The building time constant: this is a measure of the type of building construction and
indicates how quickly the room temperature would change if the outside temperature
was suddenly changed. The following guide values can be used for setting the building
time constant: 10 hours for light, 25 hours for medium, and 50 hours for heavy building
structures
•
The actual outside temperature (T
A
)
•
The composite outside temperature (T
AM
), which is the mean value of:
−
the actual outside temperature, and
−
the outside temperature filtered by the building time constant
Compared with the actual outside temperature, the composite outside temperature is
attenuated. Hence, it represents the effects of short-time outside temperature varia-
tions on the room temperature as they often occur during intermediate seasons
(spring and autumn)
•
The attenuated outside temperature (T
AD
): it is generated by filtering twice the actual
outside temperature by the building time constant. This means that, compared with the
actual outside temperature, the attenuated outside temperature is considerably damp-
ened. This ensures that no heating will take place in the summer when, under normal
circumstances, the heating would be switched on because the outside temperature
drops for a few days
