Technical Instructions
RDU20U, RDU50U and RDU50.2U Room Temperature Controllers
Document Number 155-735
with LCD for Heating and Cooling Systems
November 1, 2006
Page 2
Siemens Industry, Inc.
Accessories
ARG70
Adapter Plate for 4-inch × 4-inch conduit boxes
QAH11.1
Changeover/Remote Temperature Sensor
141-570
Lockable Thermostat Guard
Ordering
The temperature sensor, valves, and damper actuators must be ordered separately.
Table 2. Equipment Combinations.
RDU50U
and
RDU
50
.2U
Product Number
Description
Technical
Instructions
SSB61U..
0 to 10 Vdc valve actuators
155-192P25
SSC61U..
155-313P25
SQS65U
SSC61.5U
SQS65.5U
155-190P25
GDE16…
44 lb-in NSR air damper actuators
155-187P25
GLB16…
88 lb-in NSR air damper actuators
155-187P25
RDU20U
SSB81U..
Floating control valve actuators
155-195P25
SSC61U..
155-314P25
SSC81U
SQS65.5U
155-308P25
GDE131…
44 lb-in NSR air damper actuators
155-187P25
GLB131…
88 lb-in NSR air damper actuators
155-187P25
All M
o
d
el
s
Powermite MZ Series
Two-way globe zone valves
155-198P25
Powermite MZ Series
Three-way globe zone valves
155-199P25
Powermite MT Series
Two-way globe zone valves
155-196P25
Powermite MT Series
Three-way globe zone valves
155-197P25
Powermite 599 Series
Two-way ball valves
155-704P25
Function
The controller measures the room temperature with its integrated sensor or via a
remote return air temperature sensor (QAH11.1) and maintains the setpoint by
delivering continuous control commands to the actuators (0 to 10 Vdc [RDU50U and
RDU50.2U] or 24 Vac on/off, or three-position [RDU20U]). The controller provides P+I
control. The factory setting for the proportional band in heating mode is 3.6°F (2°C),
and in cooling mode 1.8°F (1°C) (adjustable). The integral action time is five minutes
(adjustable). Motor run time for the RDU20U is adjustable from 50 to 150 seconds in
10-second increments.
RDU20U
Figure 1. Heating/Cooling Modes.
C/O
Changeover
P-band Proportional band
T
Room temperature
W
Room temperature setpoint
Y
Y output percentage
NOTE:
Diagram only shows
P-characteristic
