
AZEL
TECHNOLOGIES INC.
D-500/502F PROGRAMMABLE THERMOSTAT
USER’S GUIDE
WIRING DIAGRAM:
D-500 for Heating and Cooling Systems
1
2
3 4
HEAT
COOL
COM FAN
7
9
8
10
Remote
W
Remote
W
Sensor
Sensor
AC IN
L
N
AC IN
L
N
LOCATION FOR INSTALLATION
Look for a location, which
has a constant temperature
in the house and it is not
near the door entry or air
condition outlet (see
example on Figure 1).
INSTALLATION
1. Open the top housing as shown in Figure 1 and 2 with a screw
driver:
Figure 1 Figure 2
2. Be careful not to touch or move the slide switches on the front and
the back cover. If the switches are moved from their original position,
see NOTE ON INSTALLING THE FRONT LCD COVER on page 3.
USER SETTING
Press SET button for 6 seconds to enter the user setting mode,
and set the flashing indication on LCD:
1. C/F selection: Press. +/- to choose F/C setting. Then press OK to
enter 24H/12H setting.
2. 24H/12H selection: Press. +/- to choose 24H/12H setting. Then
press OK to enter DATE setting.
3. DATE: Press. +/- to choose YEAR. Then press OK to enter Month
setting.
4. MONTH: Press +/- to choose MONTH. Then press OK to enter DAY
setting.
5. DAY: Press +/- to choose DAY. Then press OK to enter CLOCK
setting.
6. CLOCK: Press +/- and OK to adjust current HOUR and MINUTE.
Then press OK to enter DIFFERENTIAL setting.
7. DIFFERENTIAL: Press +/- to choose desired switching differential(1
or 2). Then press OK to enter FILTER setting.
8. FILTER: Press +/- to select filter hours from 100-hour to 9900-hour.
Note: for fan coil system, replacing the filter after using for certain
period of time in order to maintain the system performance. When
this function is activated, LCD will display “Reminder” signal on main
screen when the filter timer is expired. This function is not effective
for the system without FAN.
9. Press OK to return to main screen and run the settings.
Note: During this user setting mode, if no key is pressed for 30
seconds, thermostat will take the latest setting and start to run the
setting.
COOL
HEAT
FAN
OPEN: CONTROL
WINDOW CONTACT
CLOSE: NORMAL
OFF
24VAC
D-502F for Radiant Floor Heating
AC IN
AC IN
NO
NC
N
24VAC
Input
L
R/T W/T
HEATING
CONTROL
24Vac
Circuit
COM
S
S
Floor Sensor
PROGRAMMING THE THERMOSTAT
Note: During the program setting mode, the thermostat will return to
normal operating mode if no key is pressed for 30 secs.
KEY PAD DESCRIPTIONS
1. SET key: Use to enter program mode/view mode plus other
functions.
2. +/- key: + key increase or skip to next step. - key decrease or
return to previous step.
3. OK key: Press to enter setting or return to run the program.
4. RESET key: Press to reset the settings to factory default.
5. Manual Key: Override function control key.
Note: Override function is disabled if system switch
is set to OFF.
PROGRAM REVIEW
Note: Do not put system switch to OFF position.
1. Press SET.
2. Press OK to review each Temperature/Time Setting (Program)
Note: To exit program review mode, press SET key twice and then
press OK)
C. PROGRAM SETTING:
Note: Do not put system switch to OFF position. (For model with
system switch)
D-500/D-502F Thermostat has 7-Day Programs with 6
Programs/day:
To set each daily program for all 7 days
1. Press SET to enter program setting, which starts with Mo-MORN
(Monday-Morning).
2. Press +/- to adjust 1st Temperature setting (P 1 Temperature)
3. Press OK to select Mo-Morn Time setting ( P 1 Time)
4. Press +/- to adjust Time setting
5. Follow procedures above to finish Temperature/Time setting for
the rest of program period for all 7 days.
6. When finished all program setting, press SET twice and then
press OK to start running the program.

To use COPY function for setting daily program
1. Select any day of the week and complete entire Temperature/Time
setting of that day. Take that day as reference for the COPY function.
(Use the same programming procedure as above).
2. Press SET to enter program setting, and then press SET again, From
should be flashing on LCD.
3. Press + to select the day that its entire daily Temperature/Time setting
has previously been completed.
4. Press OK to confirm selected date of reference and enter next stage
copy programs to. LCD should begin to flash To on screen after
pressing OK.
5. Press + to select date that you want to copy programs to.
6. Press OK to confirm selected date. The selected date will stop flashing.
7. Press + to continue selecting more dates for copying programs to.
Press OK to confirm each selection.
8. To delete selected date, press - and the last selected date should be
flashing. Press - again to delete this date. Repeat pressing - to delete
more dates (in reverse order of selection).
Note: In COPY function mode, Date appears on LCD should always be
in sequence starting from Monday (Mo)(except For Monday was
chosen as reference, Tuesday (Tu) will appear, instead)
9. After COPY setting is finished, press OK twice to run the program.
Note: During this mode, press SET key once to exit without updating any
settings.
OVERRIDE FUNCTION
Note: Do not put system switch to OFF position
Your thermostat has four temperature override options:
Temporary, Comfort, Permanent Hold, Hold Temperature
Until (Vacation Hold).
A. Temporary Override- Change current Temperature setting
until next scheduled period time.
1.. Press + or - to adjust Temperature.(Temp. Set in flashing)
2. Wait for 10 seconds, thermostat will automatically run this
temporary override function, or press OK to run the setting.
(Users should read “Temporary Override” on LCD screen)
3. When Temporary Override is running, press OK to cancel
Temporary Override function.
For the following 3 override functions, if there is no keypad
input for 30 seconds, thermostat will resume operation.
B. Comfort Override - Change current temperature setting
and hold new setting for certain hours. Thermostat will
resume its original programmed setting when Comfort
Override function is expired.
THE BUILT-IN PROGRAMS
1. Press MANUAL key.
2. Press + or - to adjust Temperature. (Temp. Set in flashing)
3. Press OK to enter selection of duration of Comfort Override
4. Press + or - to adjust Time (minimum 1 hour).
5. Press OK to run Comfort Override.
6. When Comfort Override is running, Press OK to cancel
this command.
C. Permanent Hold Temperature - Change current
temperature setting and to execute new setting permanently
until this command is cancelled by pressing OK.
1. Press MANUAL and then press MANUAL again to choose
this override function.
2. Press + or - to adjust Temperature.(Temp. Set in flashing)
3. Press OK to run Permanent Hold Temperature
function.(LCD display will indicate that it is running)
4. When Permanent Hold Temperature is running, press OK to
cancel this command.
D. Temperature Until (Vacation Hold) - Change current
temperature setting and execute new setting until certain
date.
1. Press MANUAL key 3 times to choose this override function.
2. Press + or - to adjust Temperature. (Temp. Set in flashing)
3. Press OK to select desired duration of Hold-Temperature
Until.
4. Press + to select Month first and then Press OK again to
enter Day selection. Press + again to select desired DAY.
5. Press ‘OK’ to run Hold Temperature Until function.
6. When Hold Temperature Until is running, press OK to
cancel this command.
Note:
1. The ending time for any given date is at 11:59 for 12H-Format
and 23:59 for 24H-Format. Hence, do not set 12:00 PM for
NIGHT(P4) or 24:00 for NIGHT(P6).
2. Thermostat is designed to run programs in sequential order, do
not set program either “overlap” in time sequence, or nonsequential time setting in program setting, this will contradict to
thermostat’s operational logic.
HOW TO ERASE MEMORY BACKUP (EEPROM)
Press OK and - keys at the same time for 6 seconds, Reset
will appear on LCD display, then press Reset
button on the front housing with a pen to delete all previous
settings in the memory. Thermostat will resume its factory
preset programs.