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Siemens Building Technologies Application :21 RWD82/21 - 05.2001

HVAC Products RWD82 1

RWD82/21

RWD82 Universal Controller

Application 21

Remote set point

Room temperature control

Two stage electric heating

Control 2 stage digital

Room temperature control

Two stage ON / OFF electrical heating

Remote set point adjustment

Optional day / night set point adjustment .

........RWD82.......

RWD82/21

HLT

Room temperature sensor

Remote set point adjuster

Time clock or switch

First stage electric air heater

Second stage electric air heater

Personal computer

High limit thermostat

Pressure switch

Heater relay

Universal analogue input - main sensor

Auxiliary analogue input

Digital input

Digital output

Communication port

HLT

Digital output

• Room temperature sensor can be selected as Ni1000, Pt1000, or active sensor.

• Adjustable differential of digital output Q1.

• Adjustable set point of Q1.

• Adjustable differential of digital output Q2.

• Adjustable set point of Q2.

• 24Vac controller supply voltage

• Remote set point adjustment via auxiliary analogue input X2.

• Day / night set points can be selected via time clock or switch.

• Independent mode for the two heating outputs.

• A high limit manual reset thermostat is mounted downstream of the air electric heater,

and de-energises the heater on excessive duct temperatures. This thermostat has to

be manually reset following detection of overheating. It is often supplied by the

supplier of the electric heater.

• A pressure switch is also specified to detect loss of static pressure in the duct,

indicating loss of fan. This also de-energises the electric heater but it is auto reset and

allows electric heater function following the detection of fan operation.

These safety units can be connected directly in series with small electric heaters, but

for larger electric heaters they are connected to a heater contactor switching the

electric heater.

Supplemental features

Control

Operating modes

Safety functions

Summary of content (3 pages)

PAGE 1
RWD82/21 RWD82 Universal Controller Application 21 Remote set point Room temperature control Two stage electric heating Control 2 stage digital Room temperature control Two stage ON / OFF electrical heating Remote set point adjustment S1 X1 X2 S1 Q1 Q2 PC HLT PS HR RWD82/21 Optional day / night set point adjustment .
PAGE 2
Description of operation The temperature sensor senses the room conditions and on a fall in temperature the RWD82 via Q1 digital output energises stage 1 of the electric heater. On a further fall in temperature, Q2 digital output energises stage 2 of the electric heater. The remote set point adjuster is connected to X2 and adjusts the day set point for Q1 output. Q2 set point is adjusted by XDZ that sets the dead zone between Q1 and Q2 set points. The night set points are set on the controller.
PAGE 3
The main display shows , a) Whether Q1 is On or Off ( = off, = on ) b) Whether Q2 is On or Off ( = off, = on ) c) Whether day or night set point is selected. (¤ = day, = night) d) X1 value ( room temperature) in ° C. e) Auxiliary application selected ( REM for remote set point adjustment ) Other displays are available by pressing the + button, and the various displays are listed below in sequence from the main display.