Honeywell T8131A User manual

169-0887—1
OWNER’S GUIDE
69-0887-1
T8131A,B Programmable Thermostat
Weekday/Weekend (5-day/ 2-day)
Programmable Heat and/or Cool
Low Voltage (20 to 30 Vac)
Thermostat and Mounting Plate

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Welcome to the world of comfort and energy
savings with your new Honeywell program-
mable thermostat.
By following the programing instructions in this
manual, your new thermostat will automatically
control the temperature in your home, keeping
you comfortable while saving energy.
Direct any questions concerning the application
of this thermostat to Honeywell Customer
Assistance at 1-800-468-1502, Monday-Friday
7:00 a.m.-5:30 p.m., Central time.

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Table of Contents
Page
Prepare for Installation .................................................................................................................... 5
Remove Old Thermostat ................................................................................................................. 7
Replacing a ClockThermostat that has C or C1 Clock Terminals .................................................. 8
Install Batteries................................................................................................................................ 9
Program the Thermostat ................................................................................................................. 11
Adjust Fan Operation Switch........................................................................................................... 20
Adjust System On-Time, °F/°C........................................................................................................ 20
Mount Thermostat Mounting Plate .................................................................................................. 22
Wire Thermostat Terminals ............................................................................................................. 24
Mount Thermostat ........................................................................................................................... 28
Check Thermostat Operation After Programming and Installing..................................................... 29
Set Fan and System Switches ........................................................................................................ 31
Troubleshooting Guide .................................................................................................................... 32
Limited One-Year Warranty.................................................................................... Inside Back Cover

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RECYCLING
If this thermostat is replacing a thermo-
stat that contains mercury in a sealed
tube, do
not place your old thermostat
in the trash. See Fig. 1. Contact your
local waste management authority for
instructions regarding recycling and the
proper disposal of your old thermostat.
If you have questions, call Honeywell
Inc. at 1-800-468-1502.
Fig. 1.Typical location of a mercury switch
in a thermostat.
M3701
MERCURY
SWITCH

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Prepare for Installation
ACheck Table 1 to make sure this thermostat is compatible with your system. For more
information, call Honeywell Customer Assistance, toll-free 1-800-468-1502.
Table 1. Compatibility Chart.
System Type Compatible With T8131
Gas—Standing Pilot Yes
Gas—Electronic Ignition Yes
Gas-Fired Boilers Yes
a,b
Gas—Millivolt No
Oil-Fired Boilers Yes
a,b
Oil-Fired Furnace Yes
Electric Furnace Yes
Electric Air Conditioning Yes
Baseboard Electric (120/240 Line Volt) No
Heat Pumps/Multistage Equipment No
NOTE: Not compatible with any 120/240 volt circuit.
aCompatible with 2-wire Honeywell zone valves. Isolating relay required for 3-wire thermostats for zone valves.
Not compatible with 2-wire White-Rodgers no. 1361Valves.
bCompatible with
hot water baseboard systems. Will not work efficiently on steam or gravity systems.

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2Acquire tools and items (below) as needed.Also purchase two AA alkaline batteries; we
recommend Energizer® batteries.
M878B
CROSS-RECESSED
SCREWDRIVER HAND OR POWER
DRILL WITH 3/16 INCH
DRILL BIT, IF NEEDED TO
DRILL HOLES IN WALL
WIRE CUTTER/STRIPPER OR SHARP
KNIFE, IF NEEDED TO STRIP WIRES MASKING TAPE, IF
NEEDED TO LABEL WIRES
AS DISCONNECTED FROM
OLD THERMOSTAT
LEVEL, IF NEEDED TO LEVEL
THERMOSTAT FOR APPEARANCE

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Remove Old Thermostat
ATest to make certain that your heating
and cooling systems are working
properly. If either does not work, contact
your local heating/air conditioning dealer.
To avoid compressor damage, do not
operate the cooling system when outdoor
temperature is below 50°F (10°C).
2Turn off power to the system at the
furnace, or at the fuse/circuit breaker
panel.
3Carefully unpack your new thermostat
and mounting plate; save the package of
screws, the instructions and the receipt.
4Remove the cover from the old thermo-
stat. If it does not snap off when pulled
firmly from the bottom, check for a screw
used to lock on the cover.
5Loosen screws holding thermostat to
subbase, wallplate or wall, and lift away.
6Disconnect wires from old thermostat or
subbase. As you disconnect each wire,
use masking tape to label it with the old
terminal designation. If there are only two
wires, they do not require labeling. If
there is an extra wire that is not con-
nected to your old thermostat, you
also
will not be connecting
it to your new
thermostat. Keep the wires from falling
back into the wall by wrapping them
around a pencil as shown.
WIRES THROUGH
WALL OPENING
M5136

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Replacing a Clock Thermostat that
has C or C1 Clock Terminals?
If you are replacing a Honeywell Chronotherm®
Thermostat, you may find one or two wires that
go to the C or C1 clock terminals on the
Chronotherm® Thermostat wiring wallplate.Do
not allow them to touch, or you can damage
your transformer. Disconnect the wires and wrap
them
separately, using electrical tape. Do not
wrap them together
.Place the wires where they
do not interfere with the operation of the new
thermostat. Record the colors and terminal
designation labels of the remaining wires.
Six or More Wires?
If there are six or more wires (excluding clock
wires attached to terminals), you most likely
have a variation of a heat pump or multistage
system.This thermostat is
not compatible with
such systems. If you would like information
about which programmable thermostats will
work with your system, call Honeywell Customer
Assistance at 1-800-468-1502.
Three Thermostat Wires?
If you have three wires for heating only and
can operate the fan using the fan ON switch,
this thermostat will work with your system;
however, some hot water (zoned) heating
systems have three thermostat wires. The
thermostat will not work without installing an
isolating relay on these systems. For details,
call Honeywell Customer Assistance at 1-800-
468-1502.

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Install Batteries
IMPORTANT
Batteries must be installed for pro-
gramming and operating the thermo-
stat and heating/cooling system.
AUse two AA alkaline batteries; non-
alkaline batteries will not last as long,
and can leak, causing damage to the
thermostat or the wall surface. We
recommend Energizer® batteries.
2Make sure the thermostat is set to the
OFF position.
3Use a coin to remove the battery door.
4Install the fresh batteries as shown,
making sure positive and negative
terminals are oriented correctly.
5Replace the battery door.
As the batteries are running low, a
bAt Lo
indicator flashes for one to two months before
the batteries run out completely.Replace the
batteries as soon as possible after the indicator
starts flashing. If you do not replace the bat-
teries sometime during the flashing
bAt Lo , the
M1719C
REMOVING
BATTERY
DOOR

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indicator eventually stops flashing. bAt Lo stays
on without flashing to indicate the thermostat and
heating/cooling system have stopped working
and the batteries are almost completely dead.
After the batteries are completely dead, the
bAt
Lo
indicator disappears, leaving a completely
blank display.
Press down on the left ends of
batteries to remove them. If you
insert the new batteries within
20 to 30 seconds of removing
the old ones, you do not need
to reprogram the thermostat.
However, if the display is blank,
the batteries are dead or
incorrectly installed and you
need to reprogram. See
pages 16 to 19 to reprogram.
IMPORTANT
Although the thermostat has a low
battery indicator, replace the batteries
once a year to prevent the thermostat
and heating/cooling system from
shutting down due to lack of battery
power.
As a precaution, when
leaving home for longer
than a month, change the
batteries before you leave
to prevent the system
from shutting down due to
lack of battery power.
INSTALL TWO AA ALKALINE
BATTERIES AS SHOWN
M1713