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.
Position ON (Factory Setting)
Fan control is temperature-
independent
Fan control is temperature-
dependent
Display of temperature or setpoint
Room (or return air) temperature
display
Operating action of switch for external
operating mode changeover
Changeover activated when switch is
closed (NO)
Changeover activated when
switch is open (NC)
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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