User Guide
22
1. All zone demands for heating are terminated.
2. The demand has exceeded the Heat • Cool changeover time limit (20
minutes) while a cooling demand exists.
When heating demand is terminated, a ve minute minimum off-time delay is
initiated.
Second-stage heating is energized if the discharge air temperature is lower
than the set point of the heating staging temperature set point.
Dual-Fuel Operation
NOTE: Only Lennox communicating heat pump outdoor units may be used
with a dual-fuel system.
When both a gas furnace and a heat pump are present on the system, the
thermostat uses the balance points to determine which source to use for
heating.
When the outdoor temperature is above the low balance point, the heat pump
is always attempted rst before using the gas furnace.
In order to use the gas furnace as a primary heating source (not defrost
tempering) when the outdoor temperature is between the high and low balance
points, the following conditions must occur:
• Heat pump must be used for a minimum of 30 minutes.
• Temperature in the zone not increase by more than 0.5°F.
• Heat pump has not gone into defrost in the 30 minute period.
If any single-zone satises the specied conditions, the heat pump will stop
and the gas furnace is used to satisfy all heat calls for the next duration of the
parameter heat pump lockout time. After the heat pump lock out has expired,
the heat pump is again used as the primary heat source on the next call after
the equipment has stopped.
Emergency Heat Operation - Heat Pump Systems
When the Lennox communicating thermostat emergency heat is enabled the
unit will satisfy all heating demand with either gas or electric backup heat.
When the Emergency Heat setting is OFF, the heat pump is used to satisfy
heating demands.
Home Screen Zone Navigation
This will be displayed when the system is congured for zoning or more than
one iComfort thermostat is installed in the home. The iHarmony system can
supports zones 2 through 4. Zone 1 is the actual thermostat itself. By default,
the zones are labeled Zone 1, Zone 2, Zone 3 and Zone 4. There are also four
dots underneath the name that indicates which zone is active on the HOME
screen. Additional dots may be present if a second system is present. The
zone being displayed will be a solid white circle. See “Table 1. Home Screen
Element and Icon Descriptions” on page 4 on how to rename each zone.
Each zone can also be renamed from menu > settings > iharmony zoning.
zones
80°
80°
80°
80°
Zone 1 Zone 2 Zone 3 Zone 4
INDICATES ZONE
ACTIVE ON HOME
SCREEN
PRESS ON THIS ICON TO EDIT
THE ACTIVE ZONE NAME.
ZONES WILL CHANGE TO EDIT.
WHEN EDITING ZONES THE
PENCIL ICON CHANGES TO
IN EDIT MODE ALL OF THE ZONES
A
RE UNDERLINED. PRESS ON ANY
ZONE TO RENAME. PRESS TO
EXIT.
NOTE: ZONE NAME MUST BE 22 CHARACTERS OR
LESS.
SYSTEM
Figure 18. Zoning Pop-Up Display (single-zone)
zones
80°
80°
80°
80°
Zone 1 Zone 2 Zone 3 Zone 4
SYSTEM
SYSTEM 2
80°
Zone 1
Figure 19. Zoning Pop-Up Display (multi-zone)