Honeywell MAGICSTAT 3355 User manual

169-1012
OWNER’S GUIDE
MagicStat
®
/3355
Programmable Thermostat by Honeywell
Weekday/Weekend (5-day/ 2-day)
Programmable Heat and/or Cool
Low Voltage (20 to 30 Vac)
Thermostat and Mounting Plate
Model CT3355
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Welcome to the world of comfort and energy
savings with your new Honeywell MagicStat®
Programmable Thermostat.
Your new thermostat will automatically control
the temperature in your home, keeping you
comfortable while saving energy when pro-
grammed according to the instructions in
this manual.
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.
RECYCLINGTHERMOSTAT
If this thermostat is replacing a thermo-
stat that contains mercury in a sealed
tube, see Fig. 1, do
not place your old
thermostat in the trash. 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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Table of Contents
Step 1: Prepare For Installation ..................................................................................................... 4
Step 2: Remove Old Thermostat ................................................................................................... 6
Step 3: Install Batteries .................................................................................................................. 8
Step 4: Program Thermostat........................................................................................................ 10
Personal Programming Chart ...................................................................................................... 12
Step 5: Adjust Fan Operation Switch, as Required ................................................................... 18
Step 6: Adjust System On-Time, °F/C°, as Required ................................................................. 18
Step 7: Mount Thermostat Mounting Plate ................................................................................. 21
Step 8: Wire Thermostat Terminals ............................................................................................. 23
Step 9: Mount Thermostat............................................................................................................ 27
Step 10: Check Thermostat Operation After Programming and Installing .............................. 28
Step 11: Set Fan and System Switches ..................................................................................... 30
Troubleshooting Guide................................................................................................................. 32
Limited One-Year Warranty ................................................................................. Inside Back Cover

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Step 1: Prepare for Installation
■■Check Table 1 to make sure this thermostat is compatible with your system. If not, return to the
retailer. For more information, call Honeywell Customer Assistance, toll-free 1-800-468-1502.
Table 1. Compatibility Chart.
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. 1361 Valves.
bCompatible with
hot water baseboard systems. Will not work efficiently on steam or gravity
systems.
System Type Compatible With CT3355
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

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■■Acquire tools and items below as needed. Also purchase two AA alkaline batteries; we recom-
mend 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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Step 2: Remove Old Thermostat
■■Test 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).
■■TURN OFF POWER to system at the
furnace, or at the fuse/circuit breaker panel.
■■Carefully unpack your new thermostat and
mounting plate; save package of screws,
instructions and receipt.
■■Remove the cover from the old thermostat.
If it does not snap off when pulled firmly
from the bottom, check for a screw used to
lock on the cover.
■■Loosen screws holding thermostat to
subbase, wallplate or wall, and lift away.
■■Disconnect wires from the 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 need to be labeled. If there is an extra
wire that is not connected to your old
thermostat, you will
also not be connecting it
to your new thermostat. Wrap wires as shown
to keep them from falling back into the wall.
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 can 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 may 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 probably have
a variation of a heat pump or multistage
system. The thermostat is
not compatible with
such systems so return the product to the
place of purchase. If you would like information
about which programmable thermostats 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 works with your system.
However, some hot water (zoned) heating
systems have three thermostat wires. The
thermostat does 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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Step 3: Install Batteries
IMPORTANT
Batteries must be installed for
programming and operation of the
thermostat and heating/cooling
system.
■■Purchase two AA alkaline batteries; non-
alkaline batteries do not last as long, and
can leak, causing damage to the thermostat
or the wall surface. We recommend
Energizer® batteries.
■■Make sure the thermostat is set to the OFF
position.
■■Use a coin to remove the battery door.
■■Install the fresh batteries as shown, making
sure positive and negative terminals are
oriented correctly.
■■Replace the battery door.
As the batteries are running low, a
bAt Lo
indicator flashes for one or two months before
batteries run out completely. Replace the
batteries as soon as possible after the indicator
starts flashing. If you do not replace the
batteries sometime while
bAt Lo is flashing, the
M1719C
REMOVING 
BATTERY
DOOR

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indicator eventually stops flashing. bAt Lo
stays on without flashing, indicating the
thermostat and heating/cooling system
have stopped working when the batteries
are almost completely dead.
After the batteries are completely dead, the
bAt Lo indicator disappears, leaving a com-
pletely blank display.
Press down on the left ends of the batteries to
remove. If you insert the new batteries within
20 to 30 seconds of removing the old ones,
you do not have to reprogram the thermostat.
However, if the display is blank, the batteries
are dead or incorrectly installed and you must
reprogram. See pages 14 and 15 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 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

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Step 4: Program Thermostat
After the batteries are installed, the thermostat
can be easily programmed in your hand, before
it is installed on the wall.
If you prefer to program the thermostat after it
is installed on the wall, skip to page 18, and
return later to this programming section.
The following Personal Programming Chart
(pages 12 and 13) can be helpful for planning
your program schedule of time and tempera-
ture settings for various times of the day.
Four time periods are available during week-
days — WAKE, LEAVE, RETURN, and SLEEP.
These periods can be seen individually on the
display as you press the SET SCHEDULE key.
WAKE is the time period you want the house at
a comfortable temperature when you get up and
while you get ready for work or school. When
deciding what time to set for your WAKE period,
include extra lead time, depending on the
outside temperature and your furnace response
time, to give the furnace a head start to heat the
house before you get up. (This will be a higher
temperature during heating season, or a lower
temperature during cooling season.)
LEAVE is the time period you can set for an
energy-saving temperature while you are away
at work or school. (This will be a lower tem-
perature during heating season, or a higher
temperature during cooling season.)
RETURN is the time period you want the
house at a comfortable temperature for
activities before bedtime. When deciding what
time to set for your RETURN period, include
extra lead time, depending on the outside
temperature and your furnace response time,