Technical Instructions
RCU61U Room Temperature Controller
Document Number 155-328P25
for CAV Systems
October 6, 2016
Page 2
Siemens Industry, Inc.
Table 1. Equipment Combinations.
Product Number
Description
Technical
Instructions
SSB81U
Three-position valve
actuator
155-195P25
SSC81U
SSC81.5U*
155-314P25
SQS85.53U
155-308P25
SSB61U
0 to 10 Vdc valve
actuator
155-192P25
GLB16…
GDE16…
0 to 10 Vdc Air
damper actuator
155-187P25
* See
Wiring Diagram
.
Function
The controller measures the room temperature with its integrated sensor and maintains
the setpoint by delivering control commands.
At setpoint condition, the output is 0 Vdc. On increase in temperature in cooling mode,
the output signal goes up from 0 to 10 volts (Direct Acting
– D.A.).
The proportional band or the switching differential can be 2°F or 7°F (1°C or 4°C) in
heating mode and 1°F or 3.5°F (0.5°C or 2°C) in cooling mode (selectable with DIP
Switch No. 4).
Heating-Cooling with
Minimum Limitation
Cooling
T
Room or return air
temperature
L, L10 Output percentage
W
Room temperature set
point
Xdz
Deadband
XpH
Proportional band
heating
XpC
Proportional band
cooling
VR
0 to 100% minimum
limitation cooling output
Figure 1. RCU61U Function Diagram.
Minimum Limitation of
Cooling Signal
Using the potentiometer located on the circuit board, the cooling signal output can be
limited to a minimum value of 0 through 100%. This can be used to ensure a minimum
supply air volume. When used in connection with a VAV controller, this setting must be
taken into account. To set minimum limitation, use a screwdriver to adjust the
potentiometer (see Figure 2). Values on the scale are percentage of full operation.
