McQuay MT 155 Installation And Maintenance Manual

MT 155 Thermostat
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. Use only wiring with
insulation rated for full thermostat operating voltage. Use
copper wire only. Insulate or wirenut all un-used leads. Any
wiring, including the remote probe,may carry the full operating
voltage of the thermostat.
To avoid potential fire and/ or explosion do not use in
potentially flammable or explosive atmospheres.
Retain these instructions for future reference. You must review
your application and national and local codes to ensure that
your installation will be functional and safe.
1 Install the thermostat 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.
To use a remote sensor, remove jumper JP-1 to disable
4
local sensing. See Figure
using a remote sensor will cause improper operation of
the thermostat. Some units do not have remote sensing
capability. See Application
IM 1014 / Page 1 of 2 © 2009 McQuay International
Installation and Maintenance Manual
DANGER
1. Failure to remove JP-1 when
Notes.
Figure 1: Removing Jumper JP-1
INSTALL COVER
LOCKING SCREW
REMOVE JP1
WHEN USING A
REMOTE SENSOR
5 Reinstall the cover assembly. Install cover locking screw
provided. Reinstall the knob.
Checkout: After wiring and installation are complete,
6
energize the system and check the operation. Adjust the
thermostat as necessary to complete at least one cycle.
Be sure the thermostat and all other equipment are
functioning correctly.

Thermostat Operation

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
800-432-1342 www.mcquay.com
IM 1014
Group: Applied Air Systems
Part Number: 910102989
Date: August 2009