RCU50U and RCU50.2U Room Temperature Controllers Technical
Instructions
For VAV Systems
Document Number 155-327P25
Rev. 1, March, 2002
Siemens Building Technologies, Inc.
Page 3
Minimum Limitation of
Cooling Signal,
Continued
Figure 3. Potentiometer Location (RCU50U).
Inversion of Output
Signal
RCU50.2U
With the RCU50.2U, the output signal can be inverted with the help of DIP Switch
No. 1. If set to ON, 0V corresponds to 0% travel and 10V to 100% travel. In position
OFF, 0V corresponds to 100% travel and 10V to 0% travel.
Set Point Shifting
RCU50U
Signal Input 1 and 2 is used for outside temperature compensation. Using a 0 to 10 Vdc
signal, the set point can be shifted by ±22.5°F at 72°F set point. The neutral position is
at 5 Vdc and means no set point shift.
TH0621R1
1
0
0
5
(72ºF)
10
22.5ºF
22.5ºF
22.5ºF 22.5ºF
W2
W1
72ºF
W
T [ºF]
100
heating
cooling
Set Point Shift (K)
Input Voltage (V)
Q(%)
W
Original set point
W1
Highest set point at 10V input
W2
Lowest set point at 0V input
set point shift
(V) Input
voltage
Figure 4. Set Point Shifting (RCU50U).
Automatic Changeover
RCU50U
The water temperature measured by the changeover sensor (QAH11.1) is used by the
controller to switch from heating to cooling mode, or vice versa. When the water
temperature is above 82°F (28°C), the controller switches to heating mode; below
61°F (16°C) it switches to cooling mode.
TH0579R1
CM
HM
T
W
˚
F
(
˚
C)
61
(16)
82
(28)
M
CM Cooling
mode
HM Heating
mode
M Operating
mode
T
W
Water
temperature
Figure 5. Automatic Changeover Mode.
