What Is The Harmony Iiit Zone Control System; What Does The System Consist Of; How Do I Set The Control Center Switches - Lennox Harmony III Homeowner's Manual

What is the Harmony IIIt Zone Control System?

Lennox Harmony IIIt Zone Control System manages the dis-
tribution of conditioned air to as many as four specific areas or
zones in the home. The Harmony IIIt control is an advanced con-
trol system that allows a home to be zoned for heating and cooling
without the extra expense of purchasing two or more HVAC
(Heating, Ventilation, and Air Conditioning) systems.
This control allows the owner to heat or cool occupied areas, with-
out conditioning unused areas. The system adapts the HVAC
components to provide a balanced and comfortable environment.
What does the Harmony IIIt Zone Control System
consist of?
The principle system component is the control center which acts
as the brains" of the Harmony IIIt Zone Control System. It coor-
dinates all of the operations of thermostats, motorized dampers,
and HVAC equipment.
Harmony IIIt Zone Control System uses off-the-shelf
1-heat/1-cool, non-power-robbing, non-heat pump electronic
thermostats and motorized dampers with one of the following
Lennox HVAC systems to distribute conditioned air to zones:
Option 1. Gas Furnace with Variable Speed Blower Motor
(VSM) and either a single- or two-speed condensing unit.
Option 2. Blower coil unit with Variable Speed Blower Motor
and either a single- or two-speed heat pump.
Option 3. Gas furnace with Variable Speed Blower Motor
and heat pump.
Option 4. Adding Humiditrol
options.
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How do I set the control center switches?

The Harmony IIIt control center has only two ON/OFF switches
(see illustration). For the most part, the system relies on thermo-
stats to provide control of the desired comfort level for each zone.
The control center also has LEDs (light emitting diodes) which
light to indicate the current operating mode and which zone
dampers are closed.
NOTE − Later models of the Harmony IIIt control center board in-
cludes connecting points for a remote vacation switch which may
be installed near the Zone 1 thermostat for the homeowner's con-
venience.
1. Vacation Switch. The Harmony IIIt control center operates
in either of two modes: central mode (Vacation switch ON) or
zone mode (Vacation switch OFF).
D
Central mode (Vacation ON) − all zones receive condi-
tioned air at the same time (like traditional, non−zoned
HVAC systems). The master thermostat (located in
Zone 1) controls any heating or cooling need for all
zones in the building.
D Zone mode (Vacation OFF) − specific zones are condi-
tioned only when the demand comes from that zone.
Each zone (not necessarily each room) has its own ther-
mostat. The individual zone thermostats only work when
the control center is in zone mode.
2. Remote Vacation Switch (optional). Switching
the optional remote vacation switch to vacation
on" on forces the system to act as a conventional
central air conditioning and heating system. All
zones will be controlled by ZONE 1 room thermo-
stat and all zone dampers will remain in the open
position.
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