Robertshaw 300-205 User Manual

Your new Robertshaw thermostat has been designed to provide
accurate control and display of the room temperature. In addition, it
will also display all relevant information pertaining to your system.

The clearly marked buttons and informative display make it
extremely easy to understand and simple to use.

Please take a few moments to read the brief instructions and
familiarize yourself with the various functions in order to obtain
maximum benefit from this truly unique electronic control.

GENERAL INFORMATION

The thermostat normally displays room temperature, and whether
cooling is currently on. The six buttons on the front of the unit
allow complete control of the equipment.

Raising or lowering the setpoints in cooling is as simple as push­ing a button. In addition, you may choose to display the tempera­ture in °F or °C.

THERMOSTAT OPERATION

MODE

The 300-205 thermostat is a cooling-only control and is
permanently in the cool mode.

COOLING



Controls the cooling system only. Select the temperature you
want by pressing the  or  buttons. (The word COOL and the
temperature setting is displayed for 5 seconds.)

CELSIUS / FAHRENHEIT

Simultaneously press  and  to switch between Celsius (C) and
Fahrenheit (F) temperature display.

TEMPERATURE ACCURACY

Full temperature accuracy will only be realized after the thermo­stat has been installed and powered for at least one (1) hour.

POWER FAILURES

Your thermostat employs the latest in solid state electronic
technology.

One of the unique features of your thermostat is that there is no
battery required to maintain your selected setpoints in the event
of a power loss as the memory is unaffected by power failures of
any duration.

When power is restored, the thermostat will continue operating as
if the power had never been off.

LIMITED OVERRIDE

When the keyboard is locked (switch #2 locked), the user may
override the temperature setpoint for 1 hour by pressing either the
 or  button. The range of temperature override is ± 3 ºF or
± 3º C.

INSTALLATION INSTRUCTIONS

LOCATION

To ensure proper operation, the thermostat should be mounted on
an inside wall in a frequently occupied area of the building. In
addition, its position must be at least 18" (46cm) from any outside
wall, and approximately 5' (1.5m) above the floor in a location
with freely circulating air of an average temperature. You should
avoid the following locations:

– behind doors or in corners where freely circulating air is

unavailable;

– where direct sunlight or radiant heat from appliances might

affect control operation;
– on an outside wall;
– adjacent to, or in line with, conditioned air discharge grilles,

stairwells, or outside doors;
– where its operation may be affected by steam or water pipes or

warm air stacks in an adjacent partition space, or by an area

behind the thermostat which is not climate controlled;
– where its operation will be affected by the supply air of an adja-

cent climate control HVAC device; and
– near sources of electrical interference such as arcing relay

contacts

REMOVING THE THERMOSTAT FROM THE SUBBASE

1. Insert a flat blade screwdriver or a coin 1/8" into the slot locat-

ed in the bottom center of the thermostat case and twist 1/4
turn. When you feel or hear a “click,” grasp the case from the
bottom two corners and separate from the subbase. Some

models require more force than others when separating due to
the number of terminals on the subbase.

2. Swing the thermostat out from the bottom.

3. Lift the thermostat up and off the subbase.

4. Place the rectangular opening in the subbase over the equip-

ment control wires protruding from the wall and, using the sub­base as a template, mark the location of the two mounting
holes (exact vertical mounting is necessary only for appear­ance).

5. Use the supplied anchors and screws for mounting on drywall

or plaster; drill two 3/16" (5mm) diameter holes at the marked
locations; use a hammer to tap the nylon anchors in flush to
the wall surface and fasten subbase using the supplied screws.
(Do not overtighten!)

CAUTION

THIS DEVICE SHOULD BE INSTALLED BY A
QUALIFIED TECHNICIAN WITH DUE REGARD
FOR SAFETY, AS IMPROPER INSTALLATION
COULD RESULT IN A HAZARDOUS CONDITION

Operating Instructions

Digital Cooling Thermostat

Model 300-205

111-134C

INSTALLATION INSTRUCTIONS (CONT)

6. Connect the wires from your system to the thermostat termi­nals. Carefully dress the wires so that any excess is pushed
back into the wall cavity or junction box. Ensure that the wires
are flush to the plastic subbase. The access hole should be
sealed or stuffed to prevent drafts from the wall affecting the
thermostat.

7. Before the thermostat is reinstalled on the subbase, install the
optional clock/timer, indoor remote sensor and outdoor remote
sensor, if used. Refer to the installation instructions supplied
with each option. Also check the position of the DIP switches
on the back of the thermostat.

REPLACING THE THERMO­STAT ON SUBBASE

1. Position the thermostat on the

hinged tabs at the top of the
subbase.

2. Gently swing the thermostat

down and press on the bottom
center until it snaps into place.

THERMOSTAT COVER LOCK

You may lock the cover down to
prevent unauthorized access to
the thermostat by adding the clear
plastic lock (included in the instal­lation bag.) Insert the plastic lock
piece into the bottom of the
mounted base. The ends of the
lock piece fit snugly under the
lock pins extending from the bot­tom of the mounted base. The tab
in the middle of the lock piece
extends down from the base.
To release the locking mechanism,
press the lock piece up and into
the base while gently prying open.

THERMISTOR MOUNTING INSTRUCTIONS

Outside rear view with backplate closed

WIRING DIAGRAM

TERMINAL AND SWITCH DESIGNATIONS

RC .............24 VAC from equipment transformer

Y ................Energizes on a call for cooling

G................Energizes the fan circuit

CLK1 .........Use with remote clock/timer for

CLK1 alternate setpoints

RS2............Use to connect remote temperature sensor(s).

RS1 Refer to the instructions included
RS+V with the sensors.

CLOCK TERMINALS (OPTION) CLK1 – CLK2

This thermostat is equipped with remote clock terminals. By con­necting a remote clock/timer the thermostat can be alternated
between the DAY/NIGHT setpoints automatically.

REMOTE SENSOR (OPTION) RS1 – RS2 – RSV+1

The thermostat is designed to accept the electronic remote sen­sor (Uni-Line part #10-528), which will allow you to locate your
thermostat in an area away from view.

DIP SWITCH OPTIONS

Located on the back of the thermostat, once the subbase is
removed.

Switch #1 – Allows for a 4-minute or 2-minute minimum on/off time.
Switch #2 – Allows for the keypad to be locked or unlocked.

SPECIFICATIONS

Rated Voltage 20-30 VAC, 24 nominal
Rated Current 0.08 Amps to 1.5 Amps continuous per

output with surges to 4 Amps max.

Control Cooling: 60° to 108°F in 1° Steps
Range 16° to 40°C in 1° Steps

Thermostat
Measurement Range 28° to 124°F or 0° to 48°C

O.D.T. Displayed
Range

-50° to 124°F or -48° to 48°C

Control Accuracy ±0.5°C at 20°C, ±1°F at 68°F

300-205

CLK1

CLK2

RS2

RS1

RS+V

Y

G

RC

4 min. (on/off) 2 min. (on/off)

Unlocked Locked

1

2

Y

RC

G

CLK1

G

Y

CLK2

24 VAC
Transformer

Line
Voltage