Technical Instructions
RDX42.22U Room Temperature Controller with LCD
Document Number 155-747
March 13, 2008
Page 2
Siemens Industry, Inc.
Table 1 Equipment Combinations.
Product Number
Description
Technical
Instructions
SFA/SFP Series
Zone valve actuators
155-321P25
599 Series Zone Valves Zone valve bodies
155-320P25
GDE16…
44 lb-in NSR air damper
actuators
155-187P25
GLB16…
88 lb-in NSR air damper
actuators
155-187P25
Temperature Sensor
QAH11.1
155-329P25
Functions
The controller acquires the room temperature with its integrated sensor or via a return
air temperature sensor (QAH11.1) and maintains the setpoint by delivering two-position
control commands. The switching differential is 4°F (2°K) in heating mode (adjustable)
and 2°F (1°K) in cooling mode (adjustable).
Fan Operation
Fan operation is selected on the controller’s front panel, either in "Auto” or “Fan On”
mode.
When function "(Auto) – temperature-dependent" is selected, the fan is switched on/off
(one-speed) depending on the temperature and the control output. When function “Fan
On” is selected, the fan will run continuously (one-speed).
The fan is switched off by:
•
leaving the heating or cooling sequence, if the “Temperature-dependent fan control“
function is activated.
•
manually setting the “Heat-Off-Cool” selector to “Off”.
•
turning the controller’s power supply off.
Fan overrun
When DIP switch 2 is set to OFF, the auxiliary heater is connected, the controller is in
heating mode, and the fan overrun function is activated. When the electric heater
output (terminal 7) is switched off by the controller in the heating sequence, the fan
overrun will start based on the time delay set with parameter P08. Fan overrun has the
highest priority and overrides the controller’s Off position.
