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Your new Robertshaw thermostat has been designed to provide
accurate control and display of the room temperature. In addition, it
will also display all relevent 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
heating is currently on. The two buttons on the front of the unit
allow complete control of the equipment.

Raising or lowering the setpoints in heating is as simple as push-
ing a button. In addition, you may choose to display the tempera-
ture in °F or °C.

ENERGY STAR COMPLIANT

Energy Star labeled products use less energy than other prod-
ucts, save you money on utility bills and help protect the environ-
ment. Energy Star setpoints are now standard on all thermostats
to ensure maximum efficiency and comfort.

Non-Programmable
Heating 70°F (21°C)/Setback Heating 62°F (17°C)

THERMOSTAT OPERATION

MODE

The 300-204 thermostat is a heat-only control and is permanently
in the heat mode.

HEATING 

Controls the heating system only. Select the temperature you
want while in the heating mode by pressing the 

or 

buttons.

(The word HEAT 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 thermo-
stat 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 ºC.

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 sub-
base as a template, mark the location of the two mounting
holes (exact vertical mounting is necessary only for appear-
ance).

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 Heating Thermostat

Model    300-204

111-133

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