Engineering Notes - Siemens RDU50U Technical Instructions

Technical Instructions
Document Number 155-735
November 1, 2006

Engineering Notes

Mounting,
Installation and
Commissioning
Notes
Page 8
RDU50U with heating-cooling changeover input 2–3 and
RDU20U with heating-cooling changeover input 7–8:
• In systems without automatic changeover, the temperature sensor can be replaced
by an external switch for manual changeover.
• In systems with Heating only mode, do not connect a sensor to the controller's input.
• With Cooling only mode, the controller input must be bridged.
• Check the position of the DIP switches and change them, if necessary.
• After applying power, the controller makes a reset, which takes approximately three
seconds; it is then ready to operate.
• Mount the unit on a wall of the room to be heated or cooled. Do not mount in direct
sunlight or near other heat or refrigeration sources. (See Figure 11.)
• Mounting height is approximately 60 inches (150 cm) above the floor.
(See Figure 11.)
• The connecting wires can be run to the controller from a recessed conduit box.
Figure 11. Acceptable Mounting Locations.
• Prior to fitting the changeover sensor on a pipe, thermal conductive paste must be
applied to the location on the pipe where the sensor is to be placed.
• The cables used must satisfy the insulation requirements for 24 Vdc potential.
• To access the wire terminal block, loosen the cover screw and open the plastic
cover. See Figure 12.
Figure 12. Accessing the Wire Terminal Block.
• Sensor inputs 4–3 and 2–3 (RDU50U and RDU50.2U) and 8–9 and 8–7 (RDU20U)
carry 24 Vdc potential. If the sensor's cables must be extended, they must be suited
for 24 Vdc voltage.
• Complete installation instructions are included with the controller.
RDU20U, RDU50U and RDU50.2U Room Temperature Controllers
with LCD for Heating and Cooling Systems
Siemens Industry, Inc.