Honeywell RTH110B User Manual
RTH110B
69-1799-01
Non-programmable Electronic Thermostat
Installation and User Guide
1. Introduction
The RTH110B non-programmable thermostat can be used to control:
• a gas, fuel oil or electric furnace - 2 or 3 wires
• a central air conditioner - 2 or 3 wires
• a hot water system with or without pump - 2 wires
• a millivolt system - 2 wires
• a central heating and cooling system - 4 or 5 wires
Note: This thermostat is not compatible with heat pumps or multi-
stage systems.
q Wrap the wires around a pencil to prevent
them from falling into the wall.
r If the hole in the wall is too big, insulate it
using a non-flammable material in order
to avoid air draughts behind the thermostat.
2.2 Installing the New Baseplate
For a new installation, choose a location approximately 5 feet
(1.5 m) above the floor and on an inside wall. Avoid draughty
areas (top of staircase, air outlet, etc.), dead air spots (behind
doors), direct sunlight or areas near concealed pipes or chimneys.
Adjustment
Display
System operating
mode selector
Features
• System operating mode selection: heat, cool or off
• Fan operating mode selection: automatic or on (continuous)
• Programmable heating and cooling cycle lengths: 10, 12, 15, 20
or 30 minutes
• Temperature display in °F or °C
• Battery replacement indicator
Fan operating
mode selector
buttons
2. Installation
2.1 Removing the Old Thermostat
IN ORDER TO AVOID ANY RISK OF ELECTRIC SHOCK, CUT
POWER TO THE HEATING SYSTEM.
n Remove the old thermostat to access the wires.
Attention: If the old thermostat was mounted onto an electrical box,
it was probably powered by 120/240 volts. In this case, this thermostat cannot be used.
o Identify and label each wire (with the corresponding letter on
the wire terminal) and remove them from the terminals.
p If necessary, strip the end of each wire (maximum of 1/4 inch).
n Remove the thermostat faceplate.
o Loosen the locking screw to separate the thermostat from its
baseplate (the screw cannot be completely removed).
p Tilt the thermostat upwards.
q Mark and bore the appropriate mounting holes (or use the
existing holes). Insert the plastic anchors.
r Pass the wires through the opening of the baseplate and fix the
baseplate to the wall using the screws provided.
2.3 Connecting the Thermostat
The connection of the new thermostat should be similar to that of
the old thermostat; however, it can vary depending on the installation.
Rh Heating power supply
Rc Cooling power supply
W Heating signal
Y Cooling signal
GFan
Note: The red jumper wire between the Rc and Rh terminals must
be removed in 2- or 5-wire installations. The jumper must be used in
3- or 4-wire installations if you wish to use the mode selector switch
for the fan.
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2.3.1 2-wire Heating
2.4 Setting J2 Jumper
The jumper defines the fan operation when the fan is placed in automatic mode.
2.3.2 2-wire Cooling
2.3.3 3-wire Heating
2.3.4 3-wire Cooling
Heat relay
Cool relay
Heat relay
Fan relay
J2 jumper
Use this setting if you have an electric furnace. In
this setting, when the fan is placed in automatic
HE
mode, it works only when heating or cooling is
activated.
Use this setting if you have a gas or fuel oil furnace. In this setting, when the fan is placed in
automatic mode, it works as follows:
• When the thermostat is placed in cool mode,
HG
the fan works only when cooling is activated.
• When the thermostat is placed in heat mode,
the fan is controlled by the furnace fan control
circuitry.
2.5 Installing the Batteries
n Pull out the battery cover.
o Install the batteries as shown. Observe the polarity.
p Reinstall the battery cover. You will hear a clicking sound.
After the batteries are installed, the thermostat performs a series of
tests for approximately 5 seconds.
Afterwards, the screen displays the actual temperature. It is normal that the displayed temperature will
be higher than the ambient temperature if you hold
the thermostat in your hands. It will display the
ambient temperature after the thermostat is
installed on the wall. By default, the setpoint is 70°F (21°C).
2.3.5 4-wire Heating and Cooling
2.3.6 5-wire Heating and Cooling
Heat relay
Cool relay
Heat relay
Cool relay
Cool relay
Fan relay
2.6 Completing the Installation
Fan relay
n Once the baseplate and the batteries are installed, mount the
thermostat on the baseplate.
o Secure the thermostat using the locking screw and install the
faceplate.
p Apply power back to the system.
Fan relay
3. Basic Functions
3.1 System Operating Mode
Use the selector switch to place the system in Heating
mode (HEAT) or Cooling mode (COOL), or to turn the
system off.
Note: When you place the thermostat in Cooling mode, you might need to
wait up to five minutes before cooling can start. This is a safety feature for
the compressor. will flash on the screen until cooling can start again.
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