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OPERATION MANUAL
E2008 Lennox Industries Inc.
Dallas, Texas, USA
RETAIN THESE INSTRUCTIONS
FOR FUTURE REFERENCE
Description
The Lennox ComfortSenset 3000 Series model L3021H
non-programmable electronic thermostat is easy-to-use,
has a large, easy-to-read display, and provides excellent
temperature control. The thermostat also includes a programmable filter change reminder, and a system check indicator which will notify the user of the need for equipment
service.
Thermostat model L3021H is suitable for heat pump,
single−stage heat/single cool applications that are
matched with a gas or electric furnace.
General
These instructions are intended as a general guide and do
not supersede local codes in any way. Consult authorities
having jurisdiction before installation.
Check equipment for shipping damage. If you find any
damage, immediately contact the last carrier.
Introduction
This document describes the operation of the Lennox model
L3021H thermostat. Refer to the installation manual for
instructions regarding installation and wiring of the thermostat.
ComfortSenset 3000 Series
Model No. L3021H
Non-Programmable Thermostat
CONTROLS
506078−01
02/08
Supersedes 504,931M
Table of Contents
Thermostat 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
General 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Initial Thermostat Power-up 1. . . . . . . . . . . . . . . . . . . . .
Heating Control 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cooling Control 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Adjusting Temperature Setpoint 3. . . . . . . . . . . . . . . . .
Fan Control 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Filter Reminder 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Balance Point 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Service Indicator 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Thermostat RESET 6. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Default Thermostat Settings 6. . . . . . . . . . . . . . . . . . . .
Technical Specifications 6. . . . . . . . . . . . . . . . . . . . . . . .
Thermostat Output Table 8. . . . . . . . . . . . . . . . . . . . . . .
Initial Thermostat Power-up
When power is initially applied to the thermostat, the display will appear as shown in figure 1.
ROOM
SETPOINT
Figure 1. Display − Initial Power−Up
All display segments are momentarily activated. This occurs as a normal part of thermostat initialization. Within a
few seconds, the display will appear as shown in figure 2
(figure shows temperature in Fahrenheit units).
88
88
FAN
ON
AUTO
SYSTEM
COOL
OFF
EMG.
HEAT
Litho U.S.A.
FILTER
SERVICE
02/08 506078−01
*2P0208* *P506078-01*
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ROOM
70
FAN
AUTO
SYSTEM
Enabling and Disabling Heat Mode
Use the HEAT button to select normal heat mode, emergency heat mode, or to disable heat modes as desired. If
the thermostat is in off mode, normal heat mode is enabled
when the HEAT button is pressed. This is indicated by
HEAT in the SYSTEM box as shown in figure 4.
HEAT
Figure 2. Display − Home Screen
Figure 2 illustrates the HOME screen. Note that an indoor
room temperature of 70°F is initially displayed. After about
1 minute of warm−up time, the actual room temperature will
be displayed. HEAT mode is the system default (as indicated in the SYSTEM box at lower right).
A pale blue display backlight turns on each time a key is
pressed; then off 8 seconds after the last key is pressed.
Heating Control
The HEAT button is located behind the small door on the
right−hand side of the thermostat. See figure 3.
ROOM
SETPOINT
Figure 4. Normal Heat Mode Enabled
If the thermostat is in normal heat mode when the HEAT
button is pressed, then emergency heat mode is enabled.
This is indicated by EMG. HEAT in the SYSTEM box as
shown in figure 5.
ROOM
SETPOINT
69
64
69
64
FAN
AUTO
SYSTEM
HEAT
FAN
AUTO
SYSTEM
Figure 3. Additional Thermostat Buttons
Normal Heat Mode
In normal heat mode, both the heat pump and the backup
heat source are used to provide heat. If the thermostat detects that the heat pump is not able to provide enough heat
(as may be the case in very cold weather), then the backup
heat source is activated.
Emergency Heat Mode
In emergency heat mode, only the backup heat source
provides heat the heat pump is disabled. The backup
heat source is activated only when there is a heat demand.
EMG.
HEAT
Figure 5. Emergency Heat Mode Enabled
If the thermostat is in emergency heat mode when the
HEAT button is pressed, then heat modes are disabled.
This is indicated by OFF in the SYSTEM box as shown in
figure 6.
ROOM
SETPOINT
Figure 6. Heat Mode Disabled
69
64
FAN
AUTO
SYSTEM
OFF
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Heating Demand
The thermostat must be in either normal or emergency
heat mode in order to properly control the heating equipment. When in either heat mode, if the actual temperature is
lower than the temperature setpoint, a heating demand is detected by the thermostat. The thermostat will then activate
the heating equipment to satisfy the demand. Heating operation is indicated by a flame icon in the SYSTEM box as
shown in figure 7.
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72
FAN
AUTO
The thermostat will then activate the cooling equipment to
satisfy the demand. Cooling operation is indicated by a
snowflake icon in the SYSTEM box as shown in figure 8.
When the actual temperature drops below the temperature
setpoint, the snowflake icon will disappear. This indicates
that the cooling demand has been satisfied and that the
cooling equipment has been turned off.
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79
FAN
AUTO
SYSTEM
COOL
88
Figure 7. Heating Demand
When the actual temperature rises above the temperature
setpoint, the flame icon will disappear. This indicates that
the heating demand has been satisfied and that the heating equipment has been turned off.
NOTE − The heat pump is activated for at least 4 minutes if
no buttons are pressed during the demand interval. The
backup heat source is activated for at least 3 minutes if no
buttons are pressed during the demand interval.
Heat pump operation is locked out for 5 minutes after a demand has been satisfied. If another heat pump demand
occurs during this 5−minute interval, the flame icon will
flash; however, the heat pump will not run until the 5−minute delay has elapsed.
SYSTEM
HEAT
Cooling Control
The COOL button is located behind the small door on the
right-hand side of the thermostat. See figure 3.
Figure 8. Cooling Demand
NOTE − The cooling equipment is activated for at least 4
minutes if no buttons are pressed during the demand interval. Cooling equipment operation is locked out for 5 minutes after a demand has been satisfied. If another cooling
demand occurs during this 5−minute interval, the snowflake icon will flash; however, the cooling equipment will
not run until the 5−minute delay has elapsed.
Adjusting Temperature Setpoint
The temperature setpoint represents the desired temperature of the space around the thermostat. The default temperature setpoint is 70°F. To adjust the setpoint, press the
UP or DOWN arrow keys to the right of the display screen.
The existing setpoint will be displayed just below the actual
room temperature as shown in figure 9. Use the UP or
DOWN arrow keys to adjust the setpoint up or down. The
setpoint will increase by 1°F each time the UP key is
pressed. The setpoint will decrease by 1°F each time the
DOWN key is pressed.
Enabling and Disabling Cool Mode
Use the COOL button to enable or disable cool mode as
necessary. If the thermostat is in off mode, cool mode is
enabled when the COOL button is pressed. This is indicated by COOL in the SYSTEM box.
If the thermostat is in cool mode, cool mode is disabled
when the COOL button is pressed. This is indicated by
OFF in the SYSTEM box.
Cooling Demand
The thermostat must be in cool mode in order to properly
control the cooling equipment. When in cool mode, if the
room temperature is higher than the temperature setpoint,
a cooling demand is detected by the thermostat.
ROOM
SETPOINT
Figure 9. Setpoint Display and Adjustment
After the desired setpoint is reached, the HOME screen
will reappear after about 8 seconds.
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69
64
FAN
AUTO
SYSTEM
HEAT
L3021H THERMOSTAT
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Fan Control
The FAN button is located behind the small door on the
right-hand side of the thermostat. See figure 3. The FAN
button can be used to select either continuous fan mode or
auto fan mode.
If continuous fan mode is enabled, the fan will run continuously regardless of whether the heating or cooling equipment is running. Also, ON will be displayed in the FAN box
as shown in figure 10.
Filter Reminder
The L3021H thermostat includes a filter reminder feature.
The filter reminder can be set for 1, 3, 6, or 12−month intervals. The SETTINGS button, located behind the door on
the right−hand side of the thermostat is used to set the filter
reminder interval. See figure 3. Press the SETTINGS button from the HOME screen to display the Filter Reminder
Settings screen as shown in figure 12.
FILTER
0
ROOM
Figure 10. Fan ON with Icon
If auto fan mode is selected, the fan will only run when the
heating or cooling equipment is running. In this case,
AUTO will be displayed in the FAN box as shown in figure 11.
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FAN
ON
SYSTEM
HEAT
73
FAN
AUTO
SYSTEM
Figure 12. Filter Reminder Settings
The default setting for the filter reminder is 0, which disables the function. Use the UP arrow while in the Filter Reminder Settings screen to select the desired interval between reminders. It may be necessary to press the UP
arrow several times to access the desired setting. The
HOME screen will reappear about 10 seconds after the arrow key has been pressed for the final time.
After the programmed interval has elapsed, the FILTER reminder will be displayed as shown in figure 13. After the filter has been changed, reset the filter reminder by pressing
the SETTINGS button for 4 seconds. The screen will blink
for a few moments to indicate that the timer has been reset.
FILTER
ROOM
72
FAN
AUTO
SYSTEM
HEAT
Figure 11. Fan AUTO with Icon
To change from continuous to auto fan mode and vice versa, press the FAN button. Also note the presence of a fan
icon in the FAN box. This icon indicates that the fan is running.
506078−01 02/08
HEAT
Figure 13. Display of Filter Reminder
Balance Point
NOTE − The balance point is only available with the outdoor sensor.
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If the optional outdoor sensor (X2658) is connected to the
thermostat, balance point adjustment is available. The balance point feature allows the measured outdoor temperature to govern operation of the heat pump and backup heat
source.
Use the SETTINGS button to access the balance point
setting. If the outdoor sensor is attached to the thermostat,
press the SETTINGS button twice to access the Balance
Point Settings screen (see figure 14).
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SERVICE
FAN
AUTO
SYSTEM
ROOM
SETPOINT
Figure 14. Balance Point Setting
The balance point can be set at any temperature between
1°F and 55°F (−17°C to 13°C). A balance point setting of
zero disables the balance point function (in this case, the
thermostat behaves as if no outdoor sensor is attached).
The default balance point setting is 55°F.
To adjust the balance point up or down, press the UP or
DOWN arrow keys to the right of the display screen. The
balance point setting will increase by 1°F each time the UP
key is pressed. The balance point setting will decrease by
1°F each time the DOWN key is pressed.
After the desired balance point is reached, the HOME
screen will reappear after about eight seconds.
NOTE − The balance point feature allows the temperature
to rise or fall 3°F above or below the setpoint. This prevents
excessive cycling of the equipment when the outdoor temperature is near the balance point. For example, if the balance point is 40°F and the actual outdoor temperature is
35°F, the outdoor temperature must rise to 43°F before
equipment adjustment occurs. Conversely, if the balance
point is 40°F and the actual outdoor temperature is 45°F,
the outdoor temperature must drop to 37°F before equipment adjustment occurs.
6p
55
HEAT
Figure 15. Service Indicator Flashing
Service Indicator
When abnormal equipment operation is detected, the
SERVICE indicator will flash on the upper-right corner of
the screen. This indicates that the equipment requires service from a qualified service technician. The SERVICE indicator is shown in figure 15.
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L3021H THERMOSTAT
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Thermostat RESET
Under some abnormal conditions, it may be desirable to
reset the thermostat to its default condition. The RESET
button can be used to return the unit to normal operation
after an occurrence such as an electrical storm or power
outage.
The RESET button is an unlabeled, recessed button located behind the door on the right−hand side of the thermostat, just below the SETTINGS button. The RESET button
is visible in figure 3. Use a paper clip or small pencil to
press the RESET button. After the RESET button is
pressed, the thermostat settings will return to the defaults
listed in the Default Settings section.
Temperature Setpoint Range
Setting range: 50°F (10°C) to 90°F (32°C)
Setting resolution: 1°F (1°C)
Temperature Control Band
SP+1.5F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+0.5F Y1 off
SP W1 off
SP−0.5F Y1 on
SP−1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP−1.5F W1 on. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(SP = temperature setpoint)
(start W1 upstage timer of 30 min.)
(disable W1 upstage timer)
(without delay)
Default Thermostat Settings
Default Thermostat settings are in table 1.
Table 1. Default Thermostat Settings
Mode Heat
Setpoint 70°F (or 21°C)
Fan Auto
Filter Reminder OFF (reminder setting = 0)
Equipment Protection
Timers
reset back to zero
Technical Specifications
Thermostat Type
Electronic nonprogrammable thermostat for 1H/1C, heat
pump with electric or gas backup heat source, non−power
robbing applications.
Power Supply Range
18VAC − 30VAC (24VAC nominal), 60Hz
Temperature Display
Display Scale: Fahrenheit or Celsius user selectable (via
DIP switches)
Display range: 35°F (2°C) to 99°F (37°C)
Display resolution: 1°F (1°C)
Display Accuracy: +/−1°F
Temperature Measurement Range
Measurement Scale: Fahrenheit
Measurement Range: 35°F to 99°F
Measurement Resolution: 0.5°F
Measurement Accuracy: +/−1°F
Field Offset: via DIP switches to +/−3°F
Sampling Method: temperature measurements sampled
every 15 seconds. Displayed temperature is the average
of the last four measurements.
Figure 16. Normal Heat Mode
SP+1.5F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+0.5F emergency heat off
SP
SP−0.5F emergency heat on
SP−1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP−1.5F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(SP = temperature setpoint)
Figure 17. Emergency Heat Mode
SP+1.5F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP+0.5F Y1 on
SP
SP−0.5F Y1 off
SP−1.0F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SP−1.5F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(SP = temperature setpoint)
Figure 18. Cooling Mode
Fan Control
AUTO or ON modes.
Backup Heat Source Selection
Electric or gas furnace, selectable via DIP switch #5 (Aux
or Dual, respectively). See also Thermostat Output section.
I/O Relays
All thermostat relays are latching type to minimize power
consumption. See table 2.
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Table 2. L3021H Terminal Designations
Connections Description
O Reversing valve, cool active
B Reversing valve, heat active
R 24VAC
G Fan control
Y1 First stage cooling/heating,
compressor generated
W1 Auxiliary heating, furnace generated
L Service Indicator
C 24VAC common
E Emergency heat
T Outdoor temperature sensor
connection 1
T Outdoor temperature sensor
connection 2
Minimum Compressor ON time: 4 minutes
Minimum Furnace ON time: 3 minutes
Minimum backup furnace cycle time (elapsed time between any furnace activation and the next furnace activation): 6 minutes.
Minimum elapsed time between any compressor activation and the next compressor activation: 6 minutes.
NOTE − All protection timers (except the compressor OFF
timer) can be over−ridden if a heating or cooling demand is
initiated or terminated using the UP, DOWN, HEAT, or
COOL buttons.
Equipment Protection Override
Both the minimum compressor OFF timer and the minimum equipment cycle timer can be over−ridden by pressing and holding either the HEAT or COOL button down for 4
seconds.
Over−Temperature Protection
Thermal mechanical switch opens W1 at 93°F+/−6°F.
Filter Reminder
Settings of 0 (Off), 1, 3, 6 or 12 months are available. When
programmed time has elapsed, a FILTER indicator is displayed.
Equipment Protection Timers
Minimum Compressor OFF time: 5 minutes
Balance Point
0°F (OFF) to 55°F, user selectable.
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L3021H THERMOSTAT
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Service Reminder
The SERVICE indicator is displayed only under the following conditions:
S if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the R terminal;
OR
S if the thermostat Y1 terminal has been activated with
24VAC for at least 5 minutes, AND the L terminal is
shorted to the C terminal.
Power Loss/Recovery
Thermostat memory is retained for a minimum of 24 hours
during a power loss (includes retention of programmed
temperature setpoint, heat/cool and fan mode settings, filter reminder status, and equipment protection timers). After 24 hours of power loss, programmed settings will be
lost and replaced with default settings.
LCD Backlight
Activated for 8 seconds when any key is pressed.
NOTE − During an electrical storm or similar disturbance,
the backlight may activate for a few seconds. This is normal and will no longer occur after the electrical disturbance
has passed.
Thermostat Operating Conditions
35°F to 105°F, 5% to 90% RH
Thermostat Storage Conditions
−40°F to 185°F, 5% to 95% RH
IMPORTANT
Power must be applied for at least six consecutive
hours prior to a power loss in order for memory to
be retained for the specified time.
Thermostat Output Table
Table 3 (see page 9) provides details of the L3021H thermostat output states for various input conditions.
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Table 3. Thermostat Output States
Condition W1 Y1 G O E
Electric Heat Backup − No Outdoor Sensor
small heat demand X X
large heat demand X X X
emergency heat demand X X
cool demand X X X
no demand dc
Gas Heat Backup (Dual Fuel) − No Outdoor Sensor
small heat demand X X
large heat demand X
emergency heat demand X
cool demand X X X
no demand dc
Electric Heat Backup − Outdoor Sensor Attached
small heat demand (BBP) X X
large heat demand (BBP) X X X
small heat demand (ABP) X X
large heat demand (ABP) X X
emergency heat demand X X
cool demand X X X
no demand dc
Gas Heat Backup (Dual Fuel) − Outdoor Sensor Attached
small heat demand (BBP) X
large heat demand (BBP) X
small heat demand (ABP) X X
large heat demand (ABP) X
emergency heat demand X
cool demand X X X
no demand dc
NOTE −
S X = output is activated with 24VAC
S dc: does not care (output can be in either state, i.e., either active or inactive)
S BBP: outdoor temperature is below balance point
S ABP: outdoor temperature is above balance point
S small heat demand: temperature is between (setpoint − 1.5°F) and (setpoint − 0.5°F), and 30-minute upstage timer
has not expired (see Normal Heat Mode graph, figure 16)
S large heat demand: temperature is below (setpoint − 1.5°F), or 30-minute upstage timer has expired (see Normal Heat
Mode graph, figure 16)
S the state of the B terminal is opposite the state of the O terminal.
S data above are tabulated for AUTO fan setting. If fan setting is ON, the fan is activated in all cases.
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L3021H THERMOSTAT
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