1. Install the T155 with the two furnished mounting screws to a
standard 2” x 4” electrical box, 4-11/16” x 2-1/8” square device box
with a 2” x 4” adapter ring or to a 4” x 4” box with accessory adapter
plate.
2. For wall installations, mount the thermostat on an inside wall
approximately 5 feet above the floor. The location should provide
circulation at average room temperature. Avoid direct sunlight or
sources of hot or cold air in the room or wall.
3. Remove the knob and then the cover. Mount thermostat base
assembly to the outlet box using the screws provided, tighten the
screws evenly but do not over tighten. Make wiring connections as
noted.
4. To use a remote sensor, remove jumper JP-1 to disable local
sensing. Failure to remove JP-1 when using a remote sensor will
cause improper operation of the thermostat. Some units do not have
remote sensing capability. See Application Notes.
5. Reinstall the cover assembly. Install cover locking screw provided.
Reinstall the knob.
© Copyright 2010 PECO, Inc. All Rights Reserved P/N 68798 3220-1449 Rev2 Page 1
Installation Instructions
TA155/TB155
Knob Removal and Replacement
InstallatIon
• READ THESE INSTRUCTIONS CAREFULLY BEFORE ATTEMPTING TO
INSTALL, OPERATE OR SERVICE THIS THERMOSTAT.
• Failure to observe safety information and comply with instructions could
result in PERSONAL INJURY, DEATH AND/OR PROPERTY DAMAGE.
• To avoid electrical shock or damage to equipment, disconnect power before
installing or servicing.
• To avoid electric shock or damage to equipment, use only wiring with insula-
tion rated for full thermostat operating voltage.
• To avoid potential fire and/ or explosion do not use in potentially flammable or
explosive atmospheres.
• Retain these instructions for future reference. This product, when installed,
will be part of an engineered system whose specifications and performance
characteristics are not designed or controlled by PECO, Inc. You must
review your application and national and local codes to assure that your
installation will be functional and safe.
Temperature Range: 50°F - 90°F (10°C - 32°C)
TA155: A HEAT-OFF-COOL system switch manually selects heating
or cooling mode. In the HEAT position, only the heat output cycles
with demand. In the COOL position, only the cool output cycles with
demand. In the OFF position, heating and cooling outputs are off. Units
with a two position system switch or without a system switch must use
a load transfer switch when both heating and cooling outputs are used.
This prevents control failure and equipment damage caused by direct
cycling between loads.
TB155: An ON-OFF system switch enables auto-changeover of heating
and cooling modes. In the ON position the thermostat activates heating
or cooling outputs dependant upon the relationship between set point
and ambient temperature. Heat on to cool on dead band is 4°F. In
the OFF position, heating and cooling outputs are off. Units without
a system switch cycle between heating and cooling with a 4°F dead
band.
FAN: Some units have a switch for manual selection of fan speed. On
these units fan operation is either internally wired for fan continuous
operation or is dependant upon connection to the fan supply input.
When internally wired for fan continuous operation, the fan will be
off when the system switch is off. When dependant upon external
connections the fan may not be off with the system switch in the off
position. The fan supply input is switched to fan speed outputs (HI -
MED - LO).
SWITCHED POWER: L1 power is switched to this output any time the
system switch is out of the OFF position.
tHeRmostat opeRatIon
When removing and re-installing the T-155
knob, care must be taken.
• Align arrow to 70°F on the knob (22C) or
midrange when removing the knob.
• Reinstall knob by aligning arrow to 70°F
(22C) or midrange.
• Do not force it. When properly aligned, the
knob will slip into position.
Align arrow to 70°F
on the knob (22C)
• Use Copper wire
only, insulate or wire
nut all unused leads.
• Any wiring, including
the remote probe,
may carry the full
operating voltage of
the thermostat.
caUtIon
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caUtIon
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WaRnInG
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