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Siemens Building Technologies
Basic documentation RVD240
CE1P2384en
HVAC Products
12 Function block Space heating
27.05.2004
•
The composite outside temperature (T
AM
). Since the composite outside temperature
is attenuated compared to the actual outside temperature, it represents the effects of
short-time outside temperature variations on the room temperature as they often oc-
cur during intermediate seasons (spring time and autumn)
The thermal inertia of the house or building in the case of outside temperature varia-
tions is taken into account by including the composite outside temperature in the auto-
matic ECO function.
12.6.3 Heating
limit
The automatic ECO function necessitates a heating limit. An ECO temperature can be set
separately for each heating circuit in the range –10 K...+10 K (operating line 61). From
this setting value and the room temperature setpoint, the heating limit will be calculated.
The switching differential of 1 K for switching on / off is entered as a fixed value.
12.6.4 Mode of operation of ECO function 1
ECO function 1 operates as an automatic summer / winter function. The heating will be
switched off (mixing valve closed and heating circuit pump off) when the attenuated
outside temperature exceeds the heating limit.
The heating will be switched on again when all 3 outside temperatures have dropped
below the heating limit by the amount of the switching differential.
The heating limit is determined as follows:
Heating limit = T
RwN
+ T
ECO
(nominal room temperature setpoint plus ECO temperature).
A nominal room temperature setpoint w
N
of +20 °C and an ECO temperature T
ECO
of
–5 K result in a heating limit of +15 °C.
12.6.5 Mode of operation of ECO function 2
ECO function 2 operates as an automatic 24-hour heating limit. The heating will be
switched off (mixing valve closed and heating circuit pump off) when the actual
or
the
composite outside temperature exceeds the heating limit.
The heating will be switched on again when all 3 outside temperatures have dropped
below the heating limit by the amount of the switching differential.
The heating limit is determined as follows:
Heating limit = T
Rw akt
+ T
ECO
(current room temperature setpoint plus ECO tempera-
ture).
In contrast to ECO function 1, function 2 also considers when reduced heating is used.
A current room temperature setpoint T
Rw akt
of +18 °C and an ECO temperature of T
ECO
of –5 K result in a heating limit of +13 °C.
The heating limit has a minimum limitation; it cannot be lower than 2 °C.
12.7 Pump
overrun
Pump overrun for the heating circuit pump can be set in the range 0...40 minutes (op-
erating line 72). Setting 0 deactivates pump overrun.
12.8 Maximum
limitation
of the room temperature
The room temperature for each heating circuit can be separately limited to a maximum
value. For that purpose, a room sensor is required (sensor or room unit).
The limit value is generated from the nominal room temperature setpoint plus the value
entered on operating line 73.
Example
Example
