REMOVE OLD THERMOSTAT
1. Shut off electricity at the main fuse box until installation is
complete. Ensure that electrical power is disconnected.
2. Remove the front cover of the old thermostat. With wires
still attached, remove wall plate from the wall. If the
old thermostat has a wall mounting plate, remove the
thermostat and the wall mounting plate as an assembly.
3. Identify each wire attached to the old thermostat using
the labels enclosed with the new thermostat.
4. Disconnect the wires from old thermostat one at a time. DO
NOT LET WIRES FALL BACK INTO THE WALL.
5. Install new thermostat using the following procedures.
Figure 1.Thermostat Base
This product does not contain mercury. However, this product
may replace a unit which contains mercury.
GAS / ELEC SWITCH
Do not open mercury cells. If a cell becomes damaged, do
not touch any spilled mercury. Wearing nonabsorbent gloves,
take up the spilled mercury and place into a container which
can be sealed. If a cell becomes damaged, the unit should be
If your system is a heat pump, the GAS/ELEC Switch must be
set to ELEC (see Fig. 1) If your system is a single stage, the
switch must be set to GAS. The switch setting must agree with
the system conﬁguration selected in the conﬁguration menu.
Mercury must not be discarded in household trash. When the
unit this product is replacing is to be discarded, place in a
to send the product containing mercury.
ATTACH THERMOSTAT BASE TO WALL
“AA” Alkaline Batteries
1. Remove the packing material from the thermostat. Gently
pull the cover straight off the base. Forcing or prying on the
thermostat will cause damage to the unit.
2. Place base over hole in wall and mark mounting hole
locations on wall using base as a template (see Fig.1).
Two “AA” alkaline batteries are installed in your thermostat
with a battery tag to prevent power drainage. Prior to use,
open the battery door and remove the battery tag. To open,
pull the battery door as shown by the arrow and lift open. The
two “AA” batteries will operate all functions or maintain time
and continuously display the temperature during a loss of AC
power. Installed batteries will also allow programming prior to
installation. To replace batteries, pull the battery door shown
by the arrow and lift open. Using the polarity indicated inside
the battery door, insert the batteries. To close the battery door,
swing the door down while pulling in the direction of arrow.
Once fully down, snap the door back into position.
3. Move base out of the way. Drill mounting holes.
4. Push wires through opening in thermostat base.
5. Fasten base loosely to wall using two mounting screws.
Place a level against bottom of base, adjust until level,
and then tighten screws. (Leveling is for appearance only
and will not affect thermostat operation.) If you are using
existing mounting holes, or if holes drilled are too large and
do not allow you to tighten base snugly, use plastic screw
anchors to secure subbase.
6. Connect wires to terminals on base using appropriate
wiring schematic (see ﬁgs. 2 through 4).
Thermostat can be powered by system AC power or Battery. If
7. Push excess wire into wall and plug hole with a ﬁre-resistant
material (such as ﬁberglass insulation) to prevent drafts
from affecting thermostat operation.
displayed, thermostat is system powered with optional battery
back-up. When battery power remaining is approximately half,
will be displayed. When “Change
” is displayed,
install fresh“AA”alkaline batteries immediately.For best results,
use new premium brand alkaline batteries such as Duracell® or
Energizer®. We recommend replacing batteries every 2 years.
If the home is going to be unoccupied for an extended period
O/B TERMINAL SWITCH SELECTION
The O/B switch on this thermostat is factory set to the “O”
position. This will accommodate the majority of heat pump
applications, which require the changeover relay to be
energized in COOL. If the thermostat you are replacing or the
heat pump being installed with this thermostat requires a “B”
terminal, to energize the changeover relay in HEAT, the O/B
switch must be moved to the “B” position.
(over 3 months) and
is displayed, the batteries should be
replaced before leaving. When less than two months of battery
life remain, the setpoint temperature will offset by 10 degrees
(10 degrees cooler in Heat mode / 10 degrees warmer in Cool
mode). If offset occurs, the normal setpoint can be manually
. Another offset will occur within two
days if batteries are not replaced. To replace the batteries, set
system to OFF.