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Control sequences
Water-based fan coil
application
Compressor based
application
ON
OFF
Notes:
Heat/Cool mode
Minimum output
on/off time Y11, Y12
Fan operation
Siemens
Building Technologies
kept running all the time (e.g. in apartments or shops during unoccupied periods),
when setting parameter P21 "ON in dead zone". In this case, the fan keeps running
at minimum fan speed 1.
Used in conjunction with a valve, either for heating/cooling with changeover, heat-
ing only or cooling only.
Used in conjunction with a 1-stage compressor for cooling only or heating only.
Heating mode
T[°C]
Room temperature
W
Room temperature setpoint
Control output "Valve" or "Compressor"
Y11
The valve or compressor receives OPEN command via control output Y11 when:
• the acquired room temperature lies by half the switching differential below the
setpoint (heating mode) or above the setpoint (cooling mode), and
• control output Y11 was not energized for more than 1 minute (the "Minimum
output off time" is a fix value)
The valve or compressor receives CLOSE command via control output Y11 when:
• the acquired room temperature lies by half the switching differential above the
setpoint (heating mode) or below the setpoint (cooling mode), and
• control output Y11 was energized for more than 1 minute (the "Minimum output
on time" is a fix value)
Control output Y12 delivers a control command which is inverted to the control
command at output Y11 and which can be used for open valves normally.
When pressing the Heat/Cool mode selector, the controller will change from heat-
ing to cooling, or vice versa.
If the controller is set to "Cooling only" or "Heating only", changeover will not be
possible. Only the corresponding mode can be selected by the Heat/Cool mode
selector (parameter P22, factory setting is "manual changeover").
The minimum output on/off time of Y11 and Y12 fixed at 1 minute. It means that
any readjustment of the setpoint or of Heat/Cool mode changeover will be hold for
1 minute before Y11 and Y12 react.
The fan operates either in automatic mode or at the selected speed when using
manual mode. In automatic mode, the fan speed depends on the setpoint and the
current room temperature. When the room temperature reaches the setpoint, the
control valve will close and the fan either remains in fan speed 1 or switches off
(parameter P21, factory setting: ON in dead zone).
In "Temperature-dependent" fan control the fan switches off (see diagram below).
The individual switching differentials of the fan speed 1 (Q1 only) can be adjusted
Semi-flush-mount Room Thermostats with LCD
Cooling mode
Switching differential "Heating"
SDH
Switching differential "Cooling"
SDC
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CB1N3064en
24.08.2010
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