Product data
8 Catalog 724-2
Options and Accessories
Control Options
Manual 4-Position Fan Switch
Several styles of the four-
position fan switch (Off,
High, Med, Low) are
available for unit-mount,
remote- or wall-mount. The
remote-mount option operates
on low-voltage or line-voltage
power and can be provided with a factory-mounted, low-voltage
interface board, which contains (3) 24-volt relays with line-
voltage contactors and terminal connections. The transformer is
factory-installed and wired. The unit-mounted option operates
on line voltage.
Sequence of operation
• Off: Fan is turned off. The two-position, motorized
fresh-air damper, when supplied, is closed.
• High, Medium, Low: Fan runs continuously at the
selected speed. The two-position, motorized fresh-air
damper, when supplied, is opened.
Remote-Mounted Thermostats
Analog Thermostats
MT155 Thermostat
The MT155 series thermostat
provides On-Off control for
low-voltage or line-voltage
valves and fan motors. It is
remote- mounted. Options
include manual or automatic
changeover and three-speed
fan control for continuous or
cycling fan operation.
Analog Thermostat with 3-Position Fan Switch
This option combines the
three-position fan switch
with an electronic analog
thermostat. For two-pipe
systems with a factory
installed valve package, it can
be provided with an automatic
switch (MTB-155) to change from heating, or cooling. Or
changeover can be a manual switch (MTA-155) .
Sequence of operation
Two standard control options are available:
• Continuous fan and On-Off valve cycle operation: The
thermostat cycles the valves On and Off. The fan runs
continuously at the manually selected fan speed.
• On-Off fan and On-Off valve cycle operation: The
thermostat cycles the fan from the manually-selected fan
speed to Off and it cycles the valves On and Off.
When the system switch is in the Off position, the fan coil
system, including the fan, is shut off.
Digital Thermostats
Daikin Applied offers a
broad range of remote wall-
mounted digital thermostats
with the capability to control
On-Off, 3-wire oating and
proportional modulating
actuator, and Normally-
Closed or Normally-Open
valves. See Table 1. For more
information, refer to the Daikin McQuay publication ED
18513-1 and Installation Manuals for the specic thermostat
(also see IM 1152)
.
MT158 and MT168 Thermostat-Controllers with
Digital Display
Series MT158 and MT168
microprocessor-based
thermostat controllers
combine a proportional
integral (PI) control algorithm
with adaptive logic.
Heating and cooling
outputs for the MT158 are
individually congurable for three-wire oating control
valves or On/Off valves in the Normally-Open (NO) or
Normally-Closed (NC) modes.
Heating and cooling outputs for the MT168 provide 0-10 Vdc or
4-20 mA. An integrated, three-speed fan control switch is line-
voltage capable to allow direct connection to the fan motors.
A manual or automatic changeover is provided with remote
setback capability from a time clock or facility management
system. Features include a Fahrenheit or Celsius digital display
and built-in purge cycling which assists the controller to
determine if the system is supplying hot water or cooling.
Standard Control Mode
• On-off fan cycle operation and modulating (or On-Off)
valve operation. The controller cycles the fan from
the manually selected fan speed to Off. The controller
modulates the valves or, on the MT158, dip-switches can be
set to cycle the valves On and Off. Used for remote-mount
thermostats or with a remote room temperature sensor.