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50QE900  
Aquazone™ Water Source Heat Pump  
Commercial Light-Activated  
Programmable Thermostat  
Owner’s Manual  
Part Number 50QE900-220LA  
CONTENTS  
CONFIGURATION  
Page  
Thermostat Display — The thermostat display is locat-  
ed in the center of the thermostat. See Fig. 1. The following  
information can be displayed on the screen:  
GENERAL. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1  
CONFIGURATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-4  
Thermostat Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1  
Heat or Cool Indicator. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1  
Thermostat Front Panel Buttons . . . . . . . . . . . . . . . . . 1  
Thermostat Programming Buttons . . . . . . . . . . . . . . . 2  
Set Clock. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Programming Thermostat Schedules. . . . . . . . . . . . . 3  
OPERATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4,5  
Auto-Changeover . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Light-Activated Operation. . . . . . . . . . . . . . . . . . . . . . . . 4  
Two-Stage Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Clock Backup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Fan Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Emergency Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5  
Holiday Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5  
• mode (OFF, HEAT, COOL, AUTO, or PROGRAM ON)  
• fan setting (FAN ON or blank)  
• override indication  
• room temperature  
• desired temperature  
• service filter indicator  
•
•
•
•
•
•
time of day  
day of the week  
schedule period (Occupied 1, 2, or 3; or Unoccupied)  
setup indicator (Programming mode)  
lock indicator  
start/stop indicator (schedule period Programming mode)  
IMPORTANT: Read entire instructions before program-  
ming the thermostat.  
GENERAL  
Carrier’s Aquazone 7-day, commercial, programmable ther-  
mostats are wall-mounted, low-voltage thermostats which  
maintain room temperature by controlling the operation of an  
HVAC (heating, cooling and ventilation) system. Separate  
heating and cooling set points and auto-changeover capability  
allow occupied and unoccupied programming schedules for  
energy savings.  
Fig. 1 — Thermostat Display  
All thermostats allow up to 3 occupied and one unoccupied  
time/temperature setting to be programmed per 24-hour period.  
Each thermostat stores programs for 7 independent days.  
Batteries are not required. During power interruption the inter-  
nal NEVERLOST™ memory stores programs for an unlimited  
time.  
Heat or Cool Indicator — A Heat or Cool indicator is  
located on the bottom left cover of the thermostat. See Fig. 2.  
The light will be red if the thermostat is in Heating mode. The  
light will be green if the thermostat is in Cooling mode.  
IMPORTANT: The thermostat has a configurable security  
level. If certain functions are not available (changing set  
points, changing programming schedules), the thermostat  
security level may be configured to exclude those func-  
tions. Call the installer to reconfigure the security level.  
Thermostat Front Panel Buttons — The thermostat  
has buttons on the front cover which are used to raise or lower  
the desired set point and override the current program. See  
Fig. 2.  
SET POINT BUTTONS — The UP ARROW and DOWN  
ARROW buttons will raise or lower the current desired tem-  
perature set point. If the thermostat is in AUTO mode, pressing  
the UP ARROW or DOWN ARROW buttons will adjust both  
the heating and cooling set points. Pressing the UP ARROW or  
DOWN ARROW buttons in Cooling mode will adjust only the  
cooling set points. Pressing the UP ARROW or DOWN  
ARROW buttons in Heating mode will adjust only the heating  
set points. The UP ARROW and DOWN ARROW buttons are  
also used in Programming mode.  
A light sensor is provided on the thermostat for light activa-  
tion. When the sensor detects light (the space is occupied), the  
thermostat will enter Occupied 1 mode. If the room is dark, the  
thermostat will follow its programmed schedule.  
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.  
PC 111 Catalog No. 535-00110 Printed in U.S.A. Form 50QE-3SO Pg 1 6-03 Replaces: New  
Book 1  
4
Tab 5a 5a  
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OVERRIDE BUTTON — The Override button is used to  
force the thermostat from Unoccupied mode into the Occu-  
pied 1 mode comfort settings. The Override period will be set  
at 30 minutes. To increase the amount of time in Override  
mode, press the Override button again. Thirty minutes of over-  
ride time will be added for each time the Override button is  
pressed up to a maximum of 4 hours. After the 4-hour limit has  
been reached, press the Override button again to cancel over-  
ride mode.  
While in Override mode, the Override icon and the Occu-  
pied 1 icon will be displayed on the thermostat. The time of  
day and the minutes remaining in Override mode will alternate  
on the thermostat display.  
The set points are adjustable with the UP ARROW and  
DOWN ARROW keys during Override mode.  
NOTE: If the thermostat is in Occupied mode and the Override  
button is pressed, the thermostat will go into Unoccupied mode  
immediately. The thermostat will remain in Unoccupied mode  
until the next Occupied start time.  
The thermostat is unlocked by performing the same proce-  
dure. Press and hold the Mode button. While holding down the  
Mode button, press the Up and Down Arrow buttons simulta-  
neously. The ‘‘Locked’’ icon will be removed from the display.  
FAN BUTTON OPERATION — The Fan button selects fan  
operation. When the fan is set to FAN ON, the fan will run con-  
tinuously for improved air circulation.  
NOTE: When the thermostat is in Unoccupied mode, the fan  
will run only during heating or cooling operation, even if the  
fan is set to FAN ON; this is the energy-saving smart fan  
feature.  
When the fan is not set to FAN ON (no icon displayed on  
thermostat screen), the fan will run during heating and cooling  
operation only.  
MODE BUTTON OPERATION — The Mode button se-  
lects the operating mode of the thermostat. If OFF is selected,  
the thermostat will not enter Heating or Cooling mode. If  
HEAT is selected, the thermostat will only enter Heating mode  
(if the room temperature is below the heating set point).  
If COOL is selected, the thermostat will only enter Cooling  
mode (if the room temperature is above the cooling set point).  
If AUTO is selected, the thermostat will enter Heating or Cool-  
ing mode based on the room temperature and the heating and  
cooling set points. If PROGRAM ON is selected, the stored  
schedule is enabled and the thermostat will follow the Occu-  
pied and Unoccupied schedules stored in its memory.  
Thermostat Programming Buttons — The thermo-  
stat has programming buttons which are used to change the set  
points of the thermostat, set the modes, and program schedules.  
The programming buttons are accessible from underneath the  
thermostat cover. To access the programming buttons, pull on  
the hinged thermostat cover. See Fig. 3. The programming  
buttons are: Mode, Fan, Holiday, Program, and Set Clock.  
Auto-Changeover — When the thermostat mode is set to  
AUTO, the thermostat will provide automatic changeover from  
Heating to Cooling mode and Cooling to Heating mode when  
required. The thermostat will automatically switch to maintain  
the desired temperature setting. The thermostat does not need  
to be manually changed from heating to cooling or cooling to  
heating operation.  
HOLIDAY MODE — The Holiday button places the thermo-  
stat into Holiday mode. During Holiday mode, the unoccupied  
set points are enforced. The number of days the thermostat will  
be in Holiday mode can be set.  
The UP ARROW and DOWN ARROW buttons are used to  
scroll through programming set points. The buttons are also  
used to answer yes or no.  
KEYPAD LOCK — The thermostat has a keypad lockout  
feature which will not acknowledge front panel buttons until  
the lockout sequence is entered. To disable or lock the keypad,  
press and hold the Mode button. While holding down the Mode  
button, press the UP and DOWN ARROW buttons simulta-  
neously. The ‘‘Locked’’ icon will appear on the display.  
Set Clock — The Set Clock button allows the user to  
change the time and day displayed on the thermostat. Press the  
Set Clock button to enter Set Time mode. See Fig. 4. The cur-  
rent time will blink on and off. Press the UP ARROW and  
DOWN ARROW buttons until the correct time is shown. Hold  
down the buttons to quickly move through the time display.  
The AM and PM annunciators will automatically change. To  
scroll through by hours only, press and hold down the Fan  
button while pressing the UP or DOWN ARROW buttons. To  
ensure the schedules are properly followed, make sure that  
AM or PM is correct for the time chosen. When the correct  
time is shown, press the Mode/Next button to modify the day  
of the week. The current day will blink on and off. Press the UP  
ARROW and DOWN ARROW buttons until the correct day is  
shown. Press the Set Clock button again to exit the Set Time  
mode.  
Fig. 2 — Thermostat Front Panel Buttons  
Fig. 3 — Thermostat Programming Buttons  
Fig. 4 — Setting the Clock  
2
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Programming Thermostat Schedules — Before  
programming the thermostat, plan the thermostat daily sched-  
ule. The schedule is divided into 7 days (Monday through  
Sunday). Each day can have 2 (Occupied 1, Unoccupied), 3  
99 F (1 to 37 C). Press the Mode button to continue. See  
Fig. 5.  
3
. The heating set point for Occupied 1 will be displayed.  
Use the UP ARROW and DOWN ARROW buttons to  
raise or lower the heating set point until the desired tem-  
perature is shown. The range of acceptable values is 35 to  
(
Occupied 1, Occupied 2, Unoccupied), or 4 (Occupied 1,  
Occupied 2, Occupied 3, Unoccupied) time periods. Each  
occupied time period has a start time, stop time, heating set  
point and a cooling set point. The unoccupied time period has a  
heating set point and a cooling set point. The unoccupied time  
period is active whenever an occupied time period is not  
active. Fill in Table 1 below as an aid to programming the daily  
schedules.  
9
9 F (1 to 37 C). Press the Mode button to continue. See  
Fig. 5.  
NOTE: When the sensor detects light (the space is occupied),  
the thermostat will enter Occupied 1 mode. If the room is dark,  
the thermostat will follow its programmed schedule. The  
Occupied 1 schedule should be turned OFF to keep the ther-  
mostat from entering Occupied 1 while the room is unoccu-  
pied. If the Occupied 1 schedule is turned ON, the thermostat  
will enter Occupied 1 per the schedule regardless of light acti-  
vation. The Occupied 1 set points are used as the heating and  
cooling set points during light activation. The Unoccupied set  
points should be used as non-work hour set points (before  
Fig. 5 — Setting Occupied 1 Set Points  
8
:00 AM and after 5:00 PM) when using light activation. For  
times when the building is unoccupied during work hours  
Monday through Friday, 8:00 AM to 5:00 PM), the Occupied  
schedule should be turned ON, and can be used for moderate  
4
5
6
. The cooling set point for Unoccupied will be displayed.  
Use the UP ARROW and DOWN ARROW buttons to  
raise or lower the cooling set point until the desired tem-  
perature is shown. The range of acceptable values is 35 to  
9 F (1 to 37 C) or ‘‘OF’’ (no unoccupied cooling). Press  
the Mode button to continue.  
. The heating set point for Unoccupied will be displayed.  
Use the UP ARROW and DOWN ARROW buttons to  
raise or lower the heating set point until the desired tem-  
perature is shown. The range of acceptable values is 35 to  
99 F (1 to 37 C) or ‘‘OF’’ (no unoccupied heating). Press  
the Mode button to continue.  
. The day of the week will be shown. Use the UP ARROW  
and DOWN ARROW buttons to change the day of the  
week until the desired starting day is shown. Possible  
choices are M (Monday) through S (Sunday). Press the  
Mode button when the desired day is shown.  
(
2
energy savings with set points of 80 F for cooling and 65 F for  
heating.  
9
PROGRAMMING MODE — To program the daily sched-  
ules, perform the following procedure:  
1
. Enter Programming mode by pressing the Program  
button. The Occupied 1 annunciator will appear on the  
thermostat display. See Fig. 5. Use the UP ARROW and  
DOWN ARROW buttons to set the maximum number of  
Occupied periods available. The thermostat can be set to  
1
, 2, or 3. After the number of Occupied periods has been  
selected, press the Mode button.  
2
. The cooling set point for Occupied 1 will be displayed.  
Use the UP ARROW and DOWN ARROW buttons to  
raise or lower the cooling set point until the desired tem-  
perature is shown. The range of acceptable values is 35 to  
Table 1 — Daily Schedule Planner  
SCHEDULE  
Occupied 2  
Start / Stop / Heat / Cool  
DAY  
OF THE  
WEEK  
Occupied 1  
Start / Stop / Heat / Cool  
Occupied 3  
Start / Stop / Heat / Cool  
Unoccupied  
Heat / Cool  
Monday  
Tuesday  
Wednesday  
Thursday  
Friday  
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Saturday  
Sunday  
NOTE: The cooling temperature set point must be higher than the heating temperature set point.  
3
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7
. The Start Time for Occupied 1 will be displayed. Use the  
UP ARROW and DOWN ARROW buttons to raise or  
lower the time until the desired Start Time is shown.  
Press the Mode button to continue. See Fig. 6.  
NOTE: The thermostat will continue to follow the sched-  
ule until a new one is entered.  
•
If only one occupied schedule is selected, the Occupied  
and 3 schedules are skipped.  
2
•
If the start time is set later in the day than the stop time,  
the program will run from midnight of that day to the  
stop time and then from the start time to midnight.  
•
•
If the same start and stop times are programmed for an  
occupancy schedule, the thermostat will be in Occupied  
mode for 24 hours.  
If one occupied period starts or stops within another  
occupied period, the lower numbered schedule has pri-  
ority. For example, if schedule Occupied 3 is running  
for 24 hours and occupied schedule 2 comes on from 1  
to 3 PM, the set points from Occupied 2 are in effect  
from 1 to 3 PM.  
Fig. 6 — Start Time Display  
OVERRIDING THE SCHEDULE — The schedule can be  
overridden during operation by pressing the UP or DOWN  
ARROW buttons to change the desired temperature. The ther-  
mostat will use the new set point until the next scheduled time  
period starts.  
8
. The Stop Time for Occupied 1 will be displayed. Use the  
UP ARROW and DOWN ARROW buttons to raise or  
lower the time until the desired Stop Time is shown. Press  
the Mode button.  
. The On/Off icon will be displayed. Use the UP ARROW  
to turn the Occupied 1 period ON for this day. Use the  
DOWN ARROW to turn the Occupied 1 period OFF for  
this day.  
0. Repeat Steps 2 through 9 to program the remaining  
schedule for occupied periods 2 and 3 (if selected in  
Step 1).  
1. The Copy command can be used to copy the previous  
day’s schedule if the schedules are the same. The copy  
command becomes available after all the occupied peri-  
ods are programmed in a day. Use the UP ARROW to  
change the copy command to YES. Use the DOWN  
ARROW to change the copy command to NO. Press the  
Mode button when the choice has been made. See Fig. 7.  
OPERATION  
9
The Mode button selects the operating mode of the thermo-  
stat. If OFF is selected, the thermostat will not enter Heating or  
Cooling mode. If HEAT is selected, the thermostat will only  
enter Heating mode (if the room temperature is below the heat-  
ing set point). If COOL is selected, the thermostat will only en-  
ter Cooling mode (if the room temperature is above the cooling  
set point). If AUTO is selected, the thermostat will enter Heat-  
ing or Cooling mode based on the room temperature and the  
heating and cooling set points. If PROGRAM ON is selected,  
the stored schedule is enabled and the thermostat will follow  
the Occupied and Unoccupied schedules stored in its memory.  
1
1
Auto-Changeover — When the thermostat mode is set  
to AUTO, the thermostat will provide automatic changeover  
from Heating to Cooling mode and Cooling to Heating mode  
when required. The thermostat will automatically switch to  
maintain the desired temperature setting. The thermostat does  
not need to be manually changed from heating to cooling or  
cooling to heating operation.  
If NO was selected, the schedule will automatically  
change to the next day and the user must enter the occu-  
pied and unoccupied schedules for that day.  
NOTE: Occupied 1 schedule heating and cooling set  
points are the same for each day. Occupied 2 and 3 set  
points may be set to different values for each day of the  
week.  
If YES was selected, the schedule will be copied to the  
next day. The schedule copy may be repeated until Sun-  
day is reached. The Sunday schedule cannot be copied to  
Monday.  
Light-Activated Operation — A light sensor is pro-  
vided on the thermostat for light activation. The thermostat  
must be in Program On mode for light activation to be initiated.  
When the sensor detects light (the space is occupied), the ther-  
mostat will enter into Occupied 1 mode and heat or cool ac-  
cording to the Occupied 1 set points. If the room is dark, the  
thermostat will follow its programmed schedule.  
1
2. After all the times and set points for each day have been  
entered, press the Program button to finish entering the  
schedule.  
NOTE: Light activation does not work in Holiday mode.  
Two-Stage Operation — The second stage of heat or  
cool is turned on when the first stage has been on for a mini-  
mum of 2 minutes and the temperature differential from the set  
point is equal to or greater than the set point plus the deadband  
plus 2 degrees.  
Clock Backup — In the event of a power loss, the ther-  
mostat will keep time for a minimum of 48 hours without ex-  
ternal power or batteries.  
Fan Operation — If Fan On is selected, the fan will run  
continuously during occupied schedule (except when Mode is  
switched to OFF). The fan will be off during unoccupied  
schedule except during heating or cooling operation.  
Fig. 7 — Copy Command Display  
If Fan On is not selected, the fan will only operate during  
heating or cooling operation.  
4
Emergency Heat — Emergency heat is available for  
heat pump applications. To turn on emergency heat, press and  
hold the Fan button. While holding the Fan button, press the  
UP button for 2 seconds. An ‘‘EH’’ will be displayed. During  
emergency heat, the fan will operate and the second stage of  
heat will be energized (locking out the first stage compressor).  
To exit emergency heat, press and hold the Fan button. While  
holding the Fan button, press the UP button for 2 seconds. Dur-  
ing emergency heat, only OFF and HEAT modes are available.  
DOWN ARROWS to select the number of days that the holi-  
day schedule will be in effect. A value of 0 disables Holiday  
mode. The duration can be set from 1 to 99 days. The thermo-  
stat will enter Holiday mode on midnight of the next day after  
the mode has been activated. Holiday mode will remain in  
effect until midnight of the last configured day.  
If the Holiday mode is in effect, the number of days remain-  
ing will blink on and off and the ‘‘Unoccupied’’ icon will be  
displayed. The Override button will be active during Holiday  
mode. The Dry Contact Switch is ignored.  
Holiday Mode — When the thermostat is in Holiday  
mode, the thermostat will operate under Unoccupied set points.  
To configure and activate the Holiday mode, press the Holiday  
button. The ‘‘HOL’’ icon will be displayed along with the  
remaining days of Holiday mode operation. Press the UP or  
To turn off the Holiday mode before the remaining config-  
ured days have passed, press the Holiday button to enter the  
configuration mode. Press the DOWN ARROW to set the  
number of days to zero. Holiday mode will be disabled.  
5
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7
href="
Copyright 2003 Carrier Corporation  
Manufacturer reserves the right to discontinue, or change at any time, specifications or designs without notice and without incurring obligations.  
PC 111 Catalog No. 535-00110 Printed in U.S.A. Form 50QE-3SO Pg 8 6-03 Replaces: New  
Book 1  
4
Tab 5a 5a