Zonex MODSTAT, MODS2 Installation Instructions

Installation Instructions

ModStat

designed as a junction for two sets of 22 ga solid

WIRING

Description

The
(Plus), ModCom DDC systems, and the System 2000
GEN II control systems. The ModStat version
thermostat drives medium pressure and heavy duty,
power open/power close dampers for modulating
applications. THE MODS2 version drives low pressure,
power close / spring open dampers for 2-position
systems, which are 2000 CFM or less.

The unique grey display backlight is constantly
illuminated in the Occupied mode. The display backlight
will go out in the Unoccupied mode. If any button is
pressed while the thermostat is in the Unoccupied mode,
the backlight will illuminate for 5 seconds. The backlight
is also illuminated when the thermostat is in the 2-hour
override mode.

Installation

WIRING
All 24 volt and communication wiring connections are
made to terminal blocks on the thermostat sub-base.
The communication terminal block (RX TX / RX TX) is

copper, twisted pair communications cable. The cable
should be daisy chained from thermostat to thermostat.

See Installation Manual.

1. Install the thermostat sub-base on an interior wall
away from direct sunlight, supply air currents, or any
heat generating source. Mounting screws and
anchors are provided. The sub-base may be
installed on a vertical 2x4 electrical box.

2. Connect the control wires “R” & “C” to the 24v
terminal block. Verify R & C polarity is the same on
each thermostat.

3. On the ModStat, connect the damper control wires
from MC, RC and RO to the actuator terminals. For
MODS2 connect MC and RC to the damper motor.

4. Connect the RX TX communication wires on the
right hand terminal block; there are 2 sets of RX TX
terminals to make the daisy chain wiring easier.

is designed for the ZonexCommander

5622 Engineer Drive / Huntington Beach, CA 92649 / Office [phone] / Fax [phone]

MODSTAT / MODS2

Digital Communicating

Zone Thermostat

cont.
NOTE: For ModCom and ZonexCommander (Plus)
systems, when using shielded twisted pair wire (Belden

8450) connect the shield conductors together, as there
are no electrical connections on the thermostat base
terminals. The shield will be landed on the Command
Center on the G or TR2 terminal.
Control Wire Polarity: To insure stable system
communications, you must verify that every ModStat has
the same polarity on terminals “R” and “C”.
Refer to the ZCMAN Installation and Applications
Manual for more detailed wiring instructions.

CONFIGURATION
Addressing

Each thermostat must have a unique address from 1-20.
For System 2000 GEN II, the ModStats are addressed
from 1-10.

1. Press and hold the Menu button until you see the
system mode display on the lower right begin to change
modes; then press and hold the Heat/Cool button with
the Menu button.

2. When the display shows “address,” release the Menu
and Heat/Cool buttons, and press the UP or DN button
until the correct address is displayed in the upper right of
the display.

3. After setting the address, the thermostat will
automatically go back to normal operation; and the set
point temperature will replace the address number just
programmed.

Display Temperature Calibration
Thermostats are calibrated at the factory and should
require no further adjustment. However, the display
space temperature may be field calibrated by the
following procedure:

1. Press and hold the Heat/Cool and Select buttons

together; then press and release the UP button to
increase the display temperature by one degree.

2. To lower the temperature display, press the DN

button once, after pressing the Heat/Cool and Select

Page 1 of 2

buttons. This makes a 1 degree change.

Manual Operation

24V Terminal Block

Adjusting Set Points

The Heat or Cool set points can be displayed by
pressing the Heat/Cool button; the set point will be
indicated on the upper right of the display.

Heat - If “Heat Setting” is displayed on the top right of
the display, simply press the UP or DN button to change
the heat set point. If “Cool Setting” is displayed and you
want to change the Heat set point, press the Heat/Cool
button twice to change from “Cool Setting” to “Heat
Setting”. Then press the UP or DN button to change the
set point.

Cool - If “Cool Setting” is displayed on the top right of
the display, simply press the UP or DN button to change
the cool set point. If “Heat Setting” is displayed and you
want to change the Cool set point, press the Heat/Cool
button twice to change from “Heat Setting” to “Cool
Setting”. Then press the UP or DN button to change the
set point.

Changing Mode

The thermostats are auto changeover, but specific
modes may be selected. Auto mode is the default.

Heat only – Press and hold the Menu button and note
the mode display begin to change. Press the Select
button when Heat is displayed.

Emergency Heat - Press and hold the Menu button
and note the mode display begin to change. Press the
Select button when Emg is displayed.

Cool only - Press and hold the Menu button and note
the mode display begin to change. Press the Select
button when Cool is displayed.

System Off - Press and hold the Menu button and note
the mode display begin to change. Press the Select
button when Off is displayed.

Auto mode – Press and release the Menu button.
Override

When the thermostat displays “Unoccupied” (top of
display), a 2-hour temporary override may be initiated by
pressing the Override/Select button. When additional
override time is required, press the Override/Select
button again.

Reheat

The ModStat can be field configured for reheat
operation, including Fan Powered Boxes. To set the
ModStat for Reheat, press and hold the Heat/Cool and
Select buttons together and then press the Menu button;
release all three buttons and the ° symbol will appear
next to the heat and cool setpoint temperature display.
NOTE: An air proving switch must be wired into the
AUX output to protect the electric heating devices.

5622 Engineer Drive / Huntington Beach, CA 92649 / Office [phone] / Fax [phone]

RO – Run Open, damper (not used for MODS2)
RC – Run Closed, damper
AUX – Reheat/Aux Heat Fan
R – 24vac power input
C-MC – 24vac common / damper common
(18 ga. Minimum wire size)

Communication Terminal Block

TX – Data Transmit
RX – Data Receive
TX – Data Transmit
RX – Data Receive
(Twisted pair or shielded twisted pair)

Page 2 of 2

Rev 4/14/10