Controlling The Heat/Cool Modes Of Operation - Lennox ComfortSense L7742U Programming And Application Manual

Controlling Heat/Cool Modes of Operation
On initial power up or after an a power loss over 2
hours, the thermostat powers up at the HOME
screen in the AUTO position. If it powers up after a
power loss of less than 2 hours, it assumes the last
mode set. Pressing MODE repeatedly scrolls
through all the modes AUTO, EM HEAT, COOL,
HEAT, then back to OFF.
HEAT, COOL and OFF modes are as each name implies. AUTO
(autochangeover) allows the thermostat to switch between Heating
and Cooling, whichever mode is dictated by the indoor temperature.
EM HEAT (emergency heat) bypasses the first stage of heating (any
stage[s] of heat pump heating) and goes directly to the heat stage used
for maximum heating to more quickly warm a very cold house.
When the indoor temperature decreases or increases, the HEATING or
COOLING cycle will turn on based on the displayed mode. When the
HVAC system is on, the INFORMATION DISPLAY AREA (shown in fig-
ure 3) will display one or several operational messages (listed in the
table below). If the outdoor sensor is connected and is turned on in user
settings, outdoor temperature will be included in the displays. The table
below summarizes the information messages.
Faults, Errors, and Service Information
TEMP SENSOR ERROR, MEMORY ERROR
CALL FOR SERVICE
NO OUTDOOR SENSOR
CALL DEALER INFO
REPLACE: MEDIA FILTER; UV LAMP; HUM PAD; METAL INSERT
REMIND RESET
ROUTINE SYS CHECK−UP
REMIND RESET
NO OUTDOOR SENSOR, HUM SENSOR ERROR, HVAC ERROR DETECTED
REMIND SERVICE
DEALER INFORMATION (Edited to show dealer contact informa-
tion [2 lines])
506228−01 05/09
When the faults, errors, and service information displays appear, dy-
namic keys will appear under the second line entries, REMIND,
CLEAR, SERVICE, or RESET. Press the box to perform the action.
Information Display Area table
Operating Information
Top line: fault/error SET DATE/TIME
Default DATE/TIME (MON JAN 1 12:00 PM)
Bot. line: action
Top line: fault/error HEATING, COOLING, HUMIDIFYING, DEHUMIDIFYING,
Bot. line: action SYSTEM OFF, OUTDOOR TEMP xxF, INDOOR RH xx%,
MON SEP 24 3:OO PM
Top line: serv. req'd SCHEDULE ON, SCHEDULE OFF, WAIT, FAN ON, FAN CIRC
Bot. line: action
MON SEP 24 3:OO PM
Top line: serv. req'd
HOLD SETTING UNTIL
Bot. line: action MON SEP 24 3:OO PM
Top line: fault/error
Bot. line: action
Contact
Installing Dealer
Page 6
INFORMATION DISPLAY AREA
Figure 3. Home Screen
PRESS SCHED TO
RESUME PROGRAM
[First time start up msg]
Top line: operation msgs
Bottom line: date & time
Top line: operation msgs
Bottom line: date & time
[Alternating msgs during
a held schedule]