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Honeywell Thermostat RTH110B User Guide

Honeywell Thermostat RTH110B Feature

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Honeywell Thermostat RTH110B

Honeywell Thermostat RTH110B PRODUCT

About Honeywell

Honeywell is a multinational conglomerate company that produces a wide range of products and services for commercial and consumer markets. Their products include aerospace systems, building technologies, performance materials and technologies, safety and productivity solutions, and more. The company was founded in 1906 and is headquartered in Charlotte, North Carolina.


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 multistage systems.

Honeywell Thermostat RTH110B FI1G-


  • 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


Removing the Old Thermostat


  1. 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.
  2. Identify and label each wire (with the corresponding letter on the wire terminal) and remove them from the terminals.
  3. If necessary, strip the end of each wire (maximum of 1/4 inch). 
  4. Wrap the wires around a pencil to prevent them from falling into the wall. Honeywell Thermostat RTH110B FIG-2
  5. 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.

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 the staircase, air outlet, etc.), dead air spots (behind doors), direct sunlight or areas near concealed pipes or chimneys.

Honeywell Thermostat RTH110B FIG-3

Honeywell Thermostat RTH110B FIG-4

  1. Remove the thermostat faceplate.
  2. Loosen the locking screw to separate the thermostat from its baseplate (the screw cannot be completely removed). 
  3. Tilt the thermostat upwards.
  4. Mark and bore the appropriate mounting holes (or use the existing holes). Insert the plastic anchors.
  5. Pass the wires through the opening of the baseplate and fix the baseplate to the wall using the screws provided.

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
G Fan

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.

Honeywell Thermostat RTH110B FIG-5

Honeywell Thermostat RTH110B FIG-6

Setting J2 Jumper

The jumper defines the fan operation when the fan is placed in automatic mode.

Honeywell Thermostat RTH110B FIG-7

Installing the Batteries

Honeywell Thermostat RTH110B FIG-8

  1. Pull out the battery cover.
  2. Install the batteries as shown. Observe the polarity.
  3. 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.
Afterward, 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).

Honeywell Thermostat RTH110B FIG-9
Completing the Installation

Honeywell Thermostat RTH110B FIG-10

  1. Once the baseplate and the batteries are installed, mount the thermostat on the baseplate.
  2. Secure the thermostat using the locking screw and install the faceplate.
  3. Apply power back to the system. 

Basic Functions

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. 

Honeywell Thermostat RTH110B FIG-11

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.Honeywell Thermostat RTH110B FIG-15

will flash on the screen until cooling can start again.

Fan Operating Mode

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

Honeywell Thermostat RTH110B FIG-12

This switch is not used if you have a 2-wire installation as the fan is not connected to the thermostat.

AUTO • If you have an electric furnace (see section 2.4), the fan works only
when heating or cooling is activated.
• If you have a gas or fuel oil furnace (see section 2.4), the fan works as
• When the thermostat is placed in cool mode, the fan works only
when cooling is activated.
• When the thermostat is placed in heat mode, the fan is con
trolled by the furnace fan control circuitry.
ON The fan is always on.

Displaying the Temperature

The actual temperature is normally displayed. To view the setpoint, press once on either of the up\down 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.

Setting the Temperature

Press one of the up\down buttons until the desired temperature is displayed.

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.

Honeywell Thermostat RTH110B FIG-13

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. 

Configuration Menu

  1. To access the configuration menu, press both up\down buttons simultaneously for 3 seconds.
  2. To go to the next parameter (menu item), briefly press both up\down buttons simultaneously.
  3. To modify a parameter, press one of the up\down buttons.
  4. Repeat steps 2 and 3 if necessary.
  5. Press both up\down buttons simultaneously for 3 seconds to exit the configuration menu.

Honeywell Thermostat RTH110B FIG-14

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 (programmable)
  • 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) 


Honeywell warrants this product, excluding battery, to be free from defects in the workmanship or materials, under normal use and service, for a period of one (1) year from the date of purchase by the consumer. If at any time during the warranty period, the product is determined to be defective or malfunctions, Honeywell shall repair or replace it (at Honeywell’s option). If the product is defective,

  1. return it, with a bill of sale or other dated proof of purchase, to the place from which you purchased it, or
  2. call Honeywell Customer Care at 1-800-468-1502. Customer Care will make the determination whether the product should be returned to the following address:

Honeywell Return Goods, Dock 4 MN10-3860, 1885 Douglas Dr N, Golden Valley, MN 55422, or whether a replacement product can be sent to you.

This warranty does not cover removal or reinstallation costs. This warranty shall not apply if it is shown by Honeywell that the defect or malfunction was caused by damage that occurred while the product was in the possession of a consumer. Honeywell’s sole responsibility shall be to repair or replace the product within the terms stated above. HONEYWELL SHALL NOT BE LIABLE FOR ANY LOSS OR DAMAGE OF ANY KIND, INCLUDING ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES RESULTING, DIRECTLY OR INDIRECTLY, FROM ANY BREACH OF ANY WARRANTY, EXPRESS OR IMPLIED, OR ANY OTHER FAILURE OF THIS PRODUCT.

Some states do not allow the exclusion or limitation of incidental or consequential damages, so this limitation may not apply to you. THIS WARRANTY IS THE ONLY EXPRESS WARRANTY HONEYWELL MAKES ON THIS PRODUCT. THE DURATION OF ANY IMPLIED WARRANTIES, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, IS HEREBY LIMITED TO THE ONE-YEAR DURATION OF THIS WARRANTY. Some states do not allow limitations on how long an implied warranty lasts, so the above limitation may not apply to you.

This warranty gives you specific legal rights, and you may have other rights which vary from state to state.
If you have any questions concerning this warranty, please write Honeywell Customer Relations, 1985 Douglas Dr, Golden Valley, MN 55422 or call 1-800-468-1502. In Canada, write Retail Products ON15-02H, Honeywell Limited/Honeywell Limitée, 35 Dynamic Drive, Scarborough, Ontario M1V4Z9. 

Customer Assistance

If you have any questions about the operation of your thermostat, please go to www.honeywell.com/yourhome, or call Honeywell Customer Care toll-free at 1-800-468-1502.

FAQ’s for Honeywell Thermostat RTH110B User Guide

What’s wrong with my Honeywell thermostat?

Install fresh batteries; Examine the circuit breaker. Verify that all panel doors are closed on the interior unit; Verify that the furnace or air conditioner is receiving power by making sure the switch next to the indoor unit is turned on.

Why doesn’t my Honeywell thermostat maintain the desired temperature?

Restart the thermostat if your Honeywell one isn’t achieving the desired temperature. For ten to twenty seconds, turn off the thermostat’s power. Restart it after that. Many smart models make this simple because they can be disconnected from furnace power.

How can my Honeywell RTH110B thermostat be manually adjusted?

Setting the temperature on your Honeywell thermostat is easy if you have a manual thermostat. To adjust the temperature, simply push the up and down buttons. Until you adjust it again, the temperature you set will remain.

What are the symptoms of a broken thermostat?

Engine overheating is one of a failed thermostat’s key symptoms. The temperature gauge in the car would likely read unusually high, making it simple to detect. The valves may be stuck closed, which would explain this.

Can a thermostat display an incorrect temperature?

The temperature sensor is one of the most frequent causes of a thermostat measuring your home’s temperature erroneously or entirely failing. There are a few things you should attempt before scheduling a temperature sensor repair because it can be very difficult to replace one.

What changes the temperature on a thermostat?

Your thermostat may malfunction if the batteries are corroding, running low on power, or worn out. Start with the most frequent (and simplest to resolve) problem, which is low batteries.

How can I adjust my Honeywell RTH110B thermostat’s temperature permanently?

Press up or down until the appropriate temperature is displayed to permanently ignore the timetable. Press the Hold button to keep the new temperature for an infinite period of time. On the screen, the word “Hold” will display. If you want to stop either override or start the schedule again, click the Run button.

Has a Honeywell RTH110B thermostat a reset button?

Remove the batteries from the thermostat and turn it off. Negative to positive and positive to negative battery insertion is incorrect. Place them back in the proper order when ten seconds have passed. You’ll get a factory reset for your thermostat.

What’s the process of a Honeywell RTH110B thermostat?

When the air temperature drops below the thermostat setting, the heating turns on, and when the set temperature is achieved, it turns off. This is how it works. The temperature in the room won’t increase any faster if the thermostat is turned up.

What is a typical thermostat issue?

A typical thermostat problem frequently causes the temperature to never reach the desired level. Inside a thermostat, grime can accumulate. When this occurs, the thermostat is unable to accurately determine the indoor air temperature. Dusting the interior of the cover is a good way to clean older thermostats.

Pdf – Honeywell Thermostat RTH110B User Guide

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