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Function
Effect on d.h.w. heating
Siemens Building Technologies
HVAC Products
12.9.8 Maximum rate of flow temperature increase
T
Vw
t
t
Time
∆
t
Unit of time
T
Flow temperature setpoint
Vw
∆
T
Rate of setpoint increase per unit of time
Vw
For each heating circuit, the rate of increase of the flow temperature setpoint can be
separately limited to a maximum. In that case, the maximum rate of increase of the flow
temperature setpoint is the selected temperature per unit of time (°C per hour). This
function
• prevents cracking noises in the piping
• protects objects and construction materials that are sensitive to quick temperature
increases (e.g. antiquities)
• prevents excessive loads on heat generating equipment
The limit value is to be set on operating line 77.
This function can be deactivated (setting ---).
Limitation of the rate of increase does not act on the d.h.w. circuit.
12.10 Frost protection for the building
12.10.1 General
Frost protection for the building acts separately on both heating circuits. It makes cer-
tain that the room temperature will not fall below a certain level. If the room temperature
falls below the setpoint for frost protection, the controller will maintain a room tempera-
ture equivalent to that setpoint plus the switching differential of 1 K.
For this purpose, both the controller and the heat source must be ready to operate
(mains voltage present).
The setpoint for frost protection is to be set on the end-user level, operating line 3.
This function cannot be deactivated.
12.10.2 Mode of operation with room sensor
The controller compares the room temperature with the adjusted setpoint for frost pro-
tection. If the room temperature falls below that setpoint, the controller will activate the
heating circuit pump to maintain the flow temperature at that setpoint plus the switching
differential of 1 K.
With the room temperature sensor, frost protection for the building has priority over the
ECO function.
12.10.3 Mode of operation without room sensor
The controller continually determines the room temperature as a function of the flow
temperature.
Basic documentation RVD240
12 Function block Space heating
T
Maximum rise: =
Vw
t
∆T
Vw
––––––––
∆t
51/126
CE1P2384en
27.05.2004
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