energized, disconnect the wire from the old thermostat's
terminal and connect it either to the: 1) B terminal, if the
reversing valve is energized on a call for heat; or to the 2)
O terminal, if the reversing valve is energized on a call for
cool. If the system heats on a call for cool, or vice versa,
this wire has been connected to the wrong terminal.
ATTACH SUBBASE TO WALL
To prevent electrical shock and/or equipment
damage, disconnect electric power to system at
main fuse or circuit breaker box until installation
1. Disconnect electrical power at main fuse or circuit
RH and RC must be jumpered for single transformer heat
2. Pull wires through opening near center of subbase
and connect wires beneath terminal screws (see figs.
Special Application Terminals
The B and O terminals can provide switching for special
functions other than heat pump operation. When the
system switch is in the HEAT position, the B terminal is
energized. When the system switch is in the COOL
position, the O terminal is energized.
3. Push excess wiring into wall and plug hole with fire-
resistant material (such as fiberglass insulation) to
prevent drafts from affecting thermostat operation.
hole locations on wall.
ATTACH THERMOSTAT TO SUBBASE
1. Remove cover from thermostat base by gripping the
base in one hand. Use the other hand to pull gently at
the top or bottom of the cover.
5. Drill mounting holes.
6. Fasten subbase loosely to wall, as shown, using two
mounting screws. Place a level against bottom of
subbase, adjust until level, and then tighten mounting
screws to secure subbase. If holes in wall are too
large and do not allow you to tighten subbase snugly,
use plastic screw anchors to secure subbase.
2. Carefully remove the shipping protective packing
from the switch.
as electrical connections between thermostat and
subbase (see fig. 7).
SPECIAL SYSTEM CONFIGURATIONS
4. Snap cover on thermostat and set switches and
temperature lever to desired set point (see OPERA-
Electric Heat Furnaces (Single Transformer Systems
5. Turn on power to the system.
The subbase as shipped may not operate the fan cor-
rectly. If both the heating and cooling system must oper-
ate the fan relay, remove the yellow factory-installed
jumper wire from the Y terminal and connect it to the A
terminal. The fan should now cycle when the thermostat
calls for either heat or cool.
If two transformers are used, they MUST be in
phase. Failure to do so may result in personal
injury and/or property damage.
Wire color DOES NOT indicate polarity. Polarity is ob-
tained from an oscilloscope or voltmeter.
Heat Pump Applications
KEEP THIS AREA
CLEAR OF WIRES
This subbase WILL NOT provide multi-stage heating or
cooling operation. For single-stage heat pump applica-
tions, install a short jumper wire across terminals W and
Y. If the old thermostat has a terminal that is continuously
Figure 2. Thermostat subbase