User Manual

Siemens Building Technologies Application :48 RWD68/48 - 02.2001
HVAC Products RWD68 2
The main temperature sensor senses the room conditions and on a fall in
temperature the RWD68 via Q1 digital output switches the air electric heater on
and off as determined by the heating set point and differential settings.
On a rise in temperature the RWD68 via the Y1 analogue output modulates the
chilled water valve as determined by the cooling set point and proportional band
settings.
On a rise in relative humidity the output Y1 of the humidity controller is fed to the
X2 temperature controller and via the priority function the highest call for cooling
controls the position of the cooling valve.
Heating and cooling sequences
Y1
Q1
Cooling
Load
Setpoint
Output
Voltage
OFF
ON
SD1 SD1
22
SD1
Heating Setpoint
Min V
Max V
CCV
G
Y1
S1
D1
GO
Y..
BM
Y1
M
X1 X2MM
3367A03
X1
M
M
GO
G
24 V SN
24 V SP
N1
TOOL
PC
Q12 Q14
Q11
Q1
E1
G
G
PS
HLT
X2
N2
RWD68
N1 RWD68 temperature controller
N2 RWD68 humidity controller
X1 Main temperature sensor
X2 Input from humidity controller.
S1 Timer or summer/winter thermostat
Q1 Potential-free relay contacts for 2-position output
Y1 Proportional 0..10Vdc output
CCV
Chilled water control valve 0…10Vdc input
E1 Electrical load 2-position control
HLT High limit safety thermostat
PS Pressure switch
PC Personal Computer
Description of operation
Function diagram
Connection diagram