Honeywell RCT8100 Programmable Thermostat User Guide

June 9, 2024
Honeywell

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Honeywell RCT8100 Programmable Thermostat

Honeywell-RCT8100-Programmable-Thermostat-PRODUCT

Do you need assistance? We are here to help. Call 1-800-468-1502.

Installation is Easy

Your new thermostat has been designed for fast and easy installation. Just follow the simple step-by-step instructions in the following pages

  1. Identify your system type.
  2. Remove your old thermostat.
  3. Identify the wires.
  4. Mount the new wallplate.
  5. Connect the wires.
  6. If the wire labels don’t match.
  7. Specify the furnace type.
  8. Install the batteries.
  9. Install the thermostat.
  10. Set the system.

Identify System Type

This thermostat is compatible with the following systems:

  • Gas, oil or electric furnace
  • Central air conditioner
  • a hot water system with or without pump
  • a millivolt system
  • a central heating and cooling system

If you are not sure of your system type or if you have any other questions, call us toll-free at 1-800-468-1502.

This thermostat is not compatible with heat pumps or multi-stage systems.

Remove Old Thermostat

  1. Turn power off at the heating/cooling system.
  2. Remove old thermostat, but leave wallplate with wires attached.Honeywell-RCT8100-Programmable-Thermostat-FIG-2

MERCURY NOTICE: Do not put your old thermostat in the trash if it contains mercury in a sealed tube. Contact your local waste management authority for instructions regarding recycling and proper disposal.

Identify Wires

If any wires are not attached to your old thermostat or are attached to a terminal marked C or C1, they will not be connected to your new thermostat. Wrap the bare metal end of each of these wires with electrical tape, so it cannot touch and short other wires

Honeywell-RCT8100-Programmable-Thermostat-FIG-3

Disconnect wires and remove the old wallplate only after all wires are labeled. Wrap the wires around a pencil to prevent them from falling though the wall opening

Mount New Wallplate

Honeywell-RCT8100-Programmable-Thermostat-FIG-4

  1. Remove coverplate.
  2. Loosen screw (the screw remains captive on wallplate).
  3. Remove thermostat.
  4. Mark and drill appropriate mounting holes (or use existing holes). Insert plastic anchors. Pass wires through opening of wallplate and secure

Labels don’t match?
If a wire does not match any terminal on the thermostat, see next page.

Connect Wires (typical wiring)

Honeywell-RCT8100-Programmable-Thermostat-FIG-5

  1. Match each labeled wire with the terminal having the same letter.
  2. Loosen the terminal screws using a screwdriver, insert the wires, then tighten the screws.
  3. Push any excess wire back into the wall opening.

Connect Wires (less common wiring)

If a labeled wire does not match any terminal designation, see diagram below.

  1. Do not use C, X or B. Wrap bare end of wire with electrical tape.
  2. If wires are connected to both Rh and Rc terminals, remove jumper (see previous page).

Specify Furnace Type

Set the Jumper J2, on the back of the thermostat, if you have connected a wire to the G terminal.

  • HG Leave the jumper in this factory-set position if you have a gas or oil furnace.
  • HE Place the jumper to this position if you have an electric furnace.

Install Batteries

Honeywell-RCT8100-Programmable-Thermostat-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. Afterwards, the screen displays the actual temperature. It is normal that the displayed temperature be higher than the ambient temperature if you are holding the thermostat. The thermostat will display the ambient temperature once it is installed on the wall. By default, the setpoint is 70 °F (21 °C).

Install thermostat

  1. Mount the thermostat on the wallplate.
  2. Tighten the screw and install the coverplate.
  3. Turn power back on at the heating/cooing system.

System Setup

  1. Press both and buttons simultaneously for 3 seconds to enter or exit the setup menu.
  2. To advance to the next function, briefly press both and  buttons simultaneously.
  3. To change the setting, press the or button.

Honeywell-RCT8100-Programmable-Thermostat-FIG-12

  1. Default settings are shown in bold and underlined.
  2. See page 3 of Operating Manual.
  3. Use the system switch to switch between the two parameters.
  4. For optimal heating control, use the setting that matches your system as follows: 2=30 min (steam, gravity), 3=20 min (hot water, 90%+ high-efficiency furnace), 4=15 min (gas or oil), 5=12 min (alternate setting for gas or oil), 6=10 min (electric).
  5. The corresponding cooling cycle lengths are as follows: 2=30 min, 3=20 min, 4=15 min, 5=12 min, 6=10 min

Automation and Control Systems

Honeywell International Inc. 1985 Douglas Drive North Golden Valley, MN 55422 Honeywell Limited 35 Dynamic Drive Scarborough, Ontario M1V 4Z9
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References

Read User Manual Online (PDF format)

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