RDF20U Room Temperature Controller with LCD
Technical Instructions
For Two-Pipe Fan Coil Units with Electric Heat
Document Number 155-334
September 27, 2007
Siemens Industry, Inc.
Page 9
Table 3. DIP Switches.
DIP Switch
No.
Description
Position ON (Factory Setting)
Position OFF
1
Fan control
Fan control is temperature-
independent
Fan control is temperature-
dependent
2
Display of temperature or setpoint
Room (or return air) temperature
display
Setpoint display
3
Operating action of switch for external
operating mode changeover
Changeover activated when switch is
closed (NO)
Changeover activated when
switch is open (NC)
4
Electric heat
Active in Cooling mode
Inactive in Cooling mode
Engineering Notes
With the RDF20U, the controller input for automatic heating/cooling changeover can
also be used without the QAH11.1 cable temperature sensor:
▪
In systems without automatic changeover, the temperature sensor can be replaced
by an external switch (suited for live voltage) for manual changeover.
▪
In systems with continuous heating mode, no sensor is connected to the
controller’s input.
▪
In systems with continuous cooling mode, the controller input (7-8) must be
bridged.
Mounting,
Installation and
Commissioning
Notes
▪
Mounting location: On a wall or inside the fan coil unit.
▪
Do not mount in niches or bookshelves, behind curtains, above or near heat
sources.
▪
Do not mount in direct sunlight.
▪
Mounting height is approximately 60 inches (1.5 m) above the floor.
▪
The connecting wires can be run to the controller from a recessed conduit box.
Figure 8. Acceptable Mounting Height in Inches.
▪
Check the positions of the DIP switches and change them, if required.
▪
After applying power, the controller makes a reset during which all LCD segments
flash, indicating that the reset has been correctly made. This takes about three
seconds. Then, the controller is ready to operate.
▪
Prior to installing the changeover sensor, thermal conductive paste must be applied
to the location on the pipe where the sensor is placed.
.
.
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