Honeywell RTH1120 User Manual

RTH1120

Non-programmable Electronic Thermostat

Installation and User Guide

1. Introduction

The RTH1120 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.

Adjustment

Display

buttons

Backlight button

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.

n Remove the thermostat faceplate. o Loosen the locking screw to separate the thermostat from its

baseplate (the screw cannot be completely removed).

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

• Backlit display

• Battery replacement indicator

• Interchangeable faceplates (titanium, charcoal & taupe)

Fan operating mode selector

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).

p Tilt the thermostat upwards. q Mark and bore the appropriate mounting holes (using a 3/16”

drill bit) 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

Refer to the following table for matching the wire labels with the thermostat terminals.

RTH1120 terminals Description Wire labels

Rh Heating power supply Rh, R, 4, V Rc Cooling power supply Rc, R

W Heating signal W, W1, H

Y Cooling signal Y, Y1, M

GFan G, F

Note: Do not connect wires identified as C, X or B. Wrap the bare end of these wires with electrical tape.

Important: The red jumper wire between Rh and Rc terminals must be removed in a 5-wire installation.

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2.3.1 2-wire Heating

2.3.2 2-wire Cooling

2.3.3 3-wire Heating

2.3.4 3-wire Cooling

Heat relay

Cool relay

Heat relay

Cool relay

Fan relay

2.4 Setting J2 Jumper

The jumper specifies how the fan will operate when it is placed in automatic mode (see section 3.2).

Leave the jumper in this position if you

have a gas or oil heating system. Move the jumper to this position if you

have an electric heating system.

JP2 jumper

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).

2.6 Completing the Installation

2.3.5 4-wire Heating and Cooling

Heat relay

Cool relay

Fan relay

2.3.6 5-wire Heating and Cooling

Fan relay

Heat relay

Note: Remove the red jumper wire between terminals Rc and Rh.

Cool 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.

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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.

3.2 Fan Operating Mode

Use the selector switch to set the fan to automatic mode (AUTO) or continuous mode (ON).

Note: This switch is not used if you have a 2-wire

installation as the fan is not connected to the thermostat.

AUTO

3.3 Displaying the Temperature

The actual temperature is normally displayed. To view the setpoint, press once on either of the buttons. The setpoint is displayed for 5 seconds along with the icon.

Note: Pressing any of the buttons more than once will change

the setpoint.

The fan operates only when the heating or cooling system is On (typical setting).

The fan operates continuously. Use this setting to

improve air circulation and air cleaning.

4. Configuration Menu

DISPLAY DESCRIPTION DEFAULT SETTINGS

Temperature display

Heating cycles per hour

Cooling cycles per hour

When either the heating or cooling parameter is displayed, use the system mode selector switch to alternate between the two parameters.

For optimal heating control, use the setting that matches your system as follows: 2=30 min (steam or gravity), 3=20 min (hot water or 90%+ high-efficiency furnace), 4=15 min (gas or oil), 5=12 min (alternate setting for gas or oil), 6=10 min (electric).

The corresponding cooling cycle lengths are as follows: 2=30 min, 3=20 min, 4=15 min, 5=12 min, 6=10 min.

n To access the configuration menu, press the backlight button

for 3 seconds.

o To go to the next parameter (menu item), briefly press the back-

light button.

p To modify a parameter, press . q Repeat steps 2 and 3 if necessary. r Press the backlight button for 3 seconds to exit the configura-

tion menu.

°F °C or °F

2, 3, 4, 5 or 6

3.4 Setting the Temperature

Press one of the buttons until the desired temperature is displayed.

3.5 Backlight

The display illuminates for 12 seconds when the backlight button or either of the buttons is pressed.

3.6 Battery Replacement Indicator

An icon appears when the batteries need replacement. This icon will flash for 120 days, then the thermostat will cut power to the heating/cooling unit. The icon disappears once the batteries are replaced. The temperature settings are saved and do not need to be re-entered.

Warning: Before removing the batteries, place the

system switch on the thermostat to Off. Otherwise, the heating/cooling unit might still be running even after the batteries are removed.

5. Technical Specifications

Power supply: 2 AA batteries Maximum load: 1 A @ 24 Vac per output Setpoint range (heating): 41 to 82°F (5 to 28°C) Setpoint range (cooling): 59 to 95°F (15 to 35°C) Display range: 23 to 122°F (-5 to 50°C) Storage temperature: -2 to 122°F (-20 to 50°C) Temperature display resolution: 1°F (0.5°C) Accuracy: ± 1°F (0.5°C) Heating/cooling cycle lengths: 10, 12, 15, 20 or 30 minutes (pro-

grammable) Compressor short-cycle protection (minimum off time): 5 minutes Data memory: non-volatile Dimensions: 5 in. x 3 in. x 1 in. (127 mm x 75 mm x 28 mm)

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