Satchwell DRT Series User manual

DS 1.002 02/99
DRT
Controllers
DS 2.201 - CZU
DS 2.801/2.951 - IAC
ROOM TEMPERATURE SENSOR
with fan speed control switches
Specification No. 337-X-XXX*
The DRT Room Temperature Sensor incorporating fan speed control
switches is used in conjunction with the CZU temperature controller.
This system is used for the control of temperature zones of buildings,
such as hotel bedrooms or individual offices, which are air conditioned
by means of fan coil units. The room occupant is provided with local
adjustment of room temperature and also fan speed (ON/OFF or OFF,
1, 2 and 3), for optimum comfort settings.
The instrument can, alternatively, be applied as a remote temperature
setting unit, in conjunction with a DDU temperature sensor located in
the fan coil unit return air space, for example.
Alternative models are available to suit units with either single-speed
or 3-speed fans.
* For the full specification number replace the 4Xs with the appropriate figures
from the TYPE column in the table overleaf.

DS 1.002 2 - 4 02/99
SPECIFICATION
Sensor Control Range: 10 to 35°C.
Sensing Element: Negative temperature coefficient thermistor.
Sensor Characteristics: Non-linear. See page 3 for table of resistance values.
Sensor Wiring: 2-wire low Voltage dc, non-polarised to controller.
Switch Rating: 2.5A 250Vac. Motor full load current.12A motor starting, 250Vac
Note: Manual switches suitable for choke controlled or capacitor controlled fan motors only.
Slide switch.
Terminals: Screw-type to accept one 2.5mm2wires.
Housing: Tough fire resistant plastic case and backplate. Protection class IP20.
Ambient Temperature Limits: -10 to 55°C.
Associated Controller: CZU temperature controller. Refer to DS2.201 for details.
IAC controller. Refer to DS2.951 or DS2.801 for details. A look up table module should be used to offset the
control module RPW input by -10°C if terminals A and B are used. If terminals A and C are used, set the control
module set value to 10°C.
Type Adjustable Scale Number of Switch
Positions Switch Position Switch Function
10 to 35°C
DRT 3801 •20
1OFF ON
DRT 3851 •40
1
2
3
OFF
LOW
MEDIUM
HIGH

02/99 3 - 4 DS 1.002
CONNECTION DIAGRAMS
INSTALLATION
1. Select location for sensor which is representative of the space to
be controlled and where it will be readily affected bychanges in the
general space temperature (See Fig.4). When used as remote
setting unit, select location which is most convenient for room
occupant.
2. Remove the backplate by pushing in the fixing lugs on the top and
bottom of the sensor with a small screw driver or similar tool.
3. Thread the wires through the backplateand baffle card and fix it to
the wall or conduit box with the arrow pointing upwards. The baffle
card is used to ensure that there are no draughts from the cable
entries to influence the sensed temperature.
4. Unscrew the mains wiring cover screw and slide the cover away
from the mains terminals on the backplate.
5. Connect mains voltage wiring to switch terminals in accordance
with the appropriate scheme diagram (See Fig.2 or Fig.3). This
mains wiring must be suitably sized for the load and comply with
local regulations. When 1 CZU controls a group of fan coil units,
use interface relays or contactors for fan circuits, as required.
6. Slide the mains cover over the mains terminals and tighten the
fixing screw.
7. CZU Controllers Only
i. Connect sensor wires to non-polarised terminalsA&Cof
sensor, when used as temperature sensor (See Fig.3).
Connect to terminals A & B when used as remote setting unit.
(See Fig.3).
IAC Controllers Only
i. When connecting terminals A and C (A is the common) to an
IAC control module sensor input set the control module set
value to 10°C. This allows temperature sensing and remote
setting from the DRT.
.
ii. When connecting terminals A and B (A is the common) to an
IAC control module RPW input a 300 Ohm resistor should be
added between DRT terminal B and the IAC control module
RPW input. A Look Up Table module must also be inserted
between the control module RPW input and the DRT
connection. The Look Up Table module must be set up as
follows:-
Sensor wiring precautions:-
Refer to DS 2.201, 2.801 or 2.951 for wiring precautions.
8. Refit the sensor housing to the backplate.
DRT SWITCH WIRING DRT SENSOR CONNECTIONS
ON
OFF
SUPPLY Fan Off Indication
Fig.1
HIGH
MEDIUM
LOW
SUPPLY
OFF Fan Off Indication Fig.2
+ Room Temperature
Common
Remote Set Value
Remote Set Value
Fig.3
IN OUT
145 35
253 30
362 25
474 20
594 15
6145 10
7--- ---
Fig.4

DS 1.002 4 - 4 02/99
Satchwell Control Systems Limited
Farnham Road
Slough
Berkshire SL1 4UH
United Kingdom
Telephone[phone]
Facsimile [phone]
A Siebe Group Company © 1984 Satchwell Control Systems Limited (revised February 1999)
All rights reserved. Unauthorised copying of any part of the contents is prohibitied.
Printed in England.
DIMENSION DRAWING
Dimensions in mm
CAUTION
•This is a mains operated device. Local wiring regulations and usual
safety precautions must be observed.
•Observe sensor wiring precautions. See DS 2.201, 2.801 or 2.951.
•Do not short circuit sensor terminals for test purposes.
•Observe maximum ambient temperature.
•Interference with those parts under sealed covers renders the guarantee
void.
•Design and performance of Satchwell equipment are subject to continual
improvement and therefore liable to alteration without notice.
•Information is given for guidance only and Satchwell do not accept
responsibility for the selection or installation of its products unless
information has been given by the Company in writing relating to a specific
application.
•Aperiodic systemandtuning checkofthecontrolsystem isrecommended.
Please contact your local Satchwell Service Office for details.