Aprilaire 8840 Setup guide

Model 8840 Touch Screen
Wi-Fi Automation Thermostat
with Integrated Indoor
Air Quality Solutions
Thermostat installation location recommendations ...2
Thermostat mounting...........................2
Equipment control module installation location
recommendations..............................2
Equipment control module mounting ..............3
Thermostat wiring .............................3
Remote temperature sensor (optional) .............4
Support module wiring (optional) .................4
Equipment control module wiring .................5
Outdoor temperature sensor (included).............6
Optional wireless outdoor temperature
and humidity sensor ...........................6
Return air temperature sensor (optional) ...........7
Leaving air temperature sensor (optional) ..........7
TABLE OF CONTENTS
INSTALLATION
HVAC WIRING DIAGRAMS
POWER & RESET OPTIONS
SETUP & TESTING
REFERENCES
Power and reset options .......................11
Installer setup wizard .........................11
HVAC installer system settings tables .........11-13
General system settings table .................11
Thermostat system settings table ...........12-13
Indoor Air Quality system settings tables.......14-17
Humidifier system settings table ............. 14-15
Dehumidifier system settings table .............15
Air cleaning system settings table..............16
Fresh air system settings table .............16-17
Installer system test ..........................17
WiFi setup ..................................18
Quick reference to controls & display..........19-20
Thermostat features ..........................21
Troubleshooting ..............................22
Specifications................................23
Conventional heat/cool single transformer..........8
Conventional heat/cool two transformer ...........8
Heat pump single transformer....................9
Heat pump two transformer .....................9
INDOOR AIR QUALITY WIRING DIAGRAMS
Indoor Air Quality wiring with separate transformers ..10
Indoor Air Quality wiring with a single transformer....10
Safety &
Installation
Instructions
READ AND SAVE THESE INSTRUCTIONS

2 3
INSTALLATION
THERMOSTAT INSTALLATION LOCATION RECOMMENDATIONS
EQUIPMENT CONTROL MODULE INSTALLATION LOCATION RECOMMENDATIONS
Thermostat should be mounted:
• On an interior wall, in a frequently
occupied space.
• Approximately 5‘ above floor.
• At least 18” from outside wall.
• Thermostat can be mounted to a
vertical junction box.
Do not mount thermostat:
• Behind doors, in corners or other dead air spaces.
• In direct sunlight, near lighting fixtures, or other appliances that
give off heat.
• On an outside or unconditioned area wall.
• In the flow of a supply register, in stairwells, or near outside doors.
• On a wall with concealed pipes or ductwork.
THERMOSTAT MOUNTING
1. Remove the rear mounting plate from the thermostat.
2. Pull wires through the opening on the rear mounting plate.
3. Position and level the mounting plate of the thermostat on wall and
mark the hole locations with a pencil.
4. Drill 1/4” holes and insert supplied anchors (drywall only).
5. Place mounting plate over anchors, insert and tighten screws.
6. Seal wire entry holes to prevent drafts affecting temperature readings.
Note: Installer must touch a grounded metal object before handling the equipment control module to avoid potential
damage due to electrical discharge.
Equipment control module should be mounted:
• In a location where the temperature will not exceed 158°F (70°C) or drop below 32°F (0°C).
Do not mount equipment control module:
• On foundation walls or on the HVAC equipment or ductwork. These locations can cause moisture to condense on
the equipment control module.
90-2122
Wire specifications:
18-24 gauge thermostat wire
Installation notes:
• Ensure power at the HVAC equipment is off.
• Loosen screw terminals, insert stripped wire
and re-tighten.
• Push the excess wire back into the opening and plug the wall opening to prevent drafts.
1 –Connection to terminal 1 at equipment control module
2 –Connection to terminal 2 at equipment control module
3 –Connection to terminal 3 at equipment control module
A&B– Model 8081 or Model 8082 support module communication (optional)
T1 & T2 –Remote temperature sensor (optional)
THERMOSTAT WIRING
INSTALLATION
90-2168
EQUIPMENT CONTROL MODULE MOUNTING
The equipment control module has the following features to simplify mounting and wiring and provide for a clean
and neat installation.
• Six (6) mounting holes. One on each corner and two centered top and bottom. Any combination of these holes
may be utilized. Mount the equipment control module using 2 to 4 #8 screws appropriate for the mounting surface
substrate. (See Figure 2.)
• Wires can be routed through
the top, bottom, sides or back.
• Nylon wire ties can be used
to secure wires in 10 places.
Installation Steps
1. Select mounting location.
2. Pull from bottom to remove
front cover. (See Figure 1.)
3. Mount base using 2 to 4 #8
screws (field supplied). Figure 1 Figure 2

4 5
REMOTE TEMPERATURE SENSOR (OPTIONAL)
A remote temperature sensor can be used for control if the thermostat is to be mounted in a concealed location
or a remote sensor can be averaged with the thermostat sensor to control a large space. An 8051 flush mount
or 8053 surface mount remote temperature sensor can be attached to the T1 and T2 terminals and mounted in a
recommended area. The remote sensor must be enabled in the installer setup menu, and once enabled will override
or be averaged with the thermostat’s internal temperature sensor, based on the setting.
Remote temperature sensor should
be mounted:
• On an interior wall, in a frequently
occupied space.
• Approximately 5‘ above floor.
• At least 18” from outside wall.
• Using less than 300’ of wire.
Do not mount remote sensor:
• Behind doors, in corners or other dead
air spaces.
• In direct sunlight, near lighting fixtures,
or other appliances that give off heat.
• On an outside or unconditioned area wall.
• In the flow of a supply register, in stairwells,
or near outside doors.
• On a wall with concealed pipes or ductwork.
• Near 120 VAC lines.
INSTALLATION
90-2124
SUPPORT MODULE WIRING (OPTIONAL)
3
T1
T2
B
A
C
RC T3
T2T1 RSARSB T4
MODEL 8081 OR 8082
SUPPORT MODULE
2
1
Up to 4 support modules can be wired for remote
sensing of temperature and/or humidity. Each sensor
can be configured for control or monitoring.
Note: Support modules should be wired with CAT-5
wire. The total length of wire for all support modules
should not exceed 1000 feet.
90-2169
INSTALLATION
EQUIPMENT CONTROL MODULE WIRING
Wire specifications:
18-24 gauge thermostat wire
Installation notes:
• Ensure power at the HVAC equipment is off.
• Loosen screw terminals, insert stripped wire
and re-tighten.
• Use zip tie to route wiring through the wiring
channels.
1 – Connection to terminal 1 at thermostat
2 – Connection to terminal 2 at thermostat
3 – Connection to terminal 3 at thermostat
RAT – Return air temperature sensor (optional)
LAT – Leaving air temperature sensor (optional)
ODT – Outdoor temperature sensor (included)
C– 24VAC common
R– 24VAC
RC – 24VAC cooling
RH – 24VAC heating
W– First stage heat (conventional)/auxiliary (heat pump)
W2 – Second stage heat (conventional)/ auxiliary (heat
pump)
W3/B – Third stage heat (conventional)/reversing valve
(heat pump)
Y– First stage cooling (conventional)/first stage compressor
(heat pump)
Y2 – Second stage cooling (conventional)/second stage
compressor (heat pump).
Y3/0 – Third stage cooling (conventional)/reversing valve
(heat pump)
G– Fan
L– System fault indicator (heat pump only) (optional)
CEQ – 24VAC common from heat pump for system fault
indicator (optional)
HUM – Humidifier
DHno & DHcom – Normally open dehumidifier control
DHnc & DHcom – Normally closed dehumidifier control
VENT – Ventilation
EAC – Electronic Air Cleaner

6 7
INSTALLATION
OUTDOOR TEMPERATURE SENSOR (INCLUDED)
OPTIONAL WIRELESS OUTDOOR TEMPERATURE AND HUMIDITY SENSOR
Outdoor temperature can be measured by installing an 8052 sensor to the ODT terminals and enabling the outdoor
sensor in the installer setup menu. When an outdoor sensor is installed, the features below will be enabled.
In heat pump mode the outdoor temperature sensor can be used to efficiently utilize an air source heat pump:
• When the outdoor temperature is less than the Low Balance Point, the heat pump will be locked out and only
auxiliary heating will be used to provide heating.
• When the outdoor temperature is higher than the High Balance Point, the auxiliary heating will be locked out and
only the heat pump will be used to provide heating.
Indoor Air Quality functions can use the outdoor temperature sensor to:
• Control humidification setpoint based on outdoor temperature to prevent condensation
• Lock out humidification for temperatures over 60°F or below -30°F.
• Lock out ventilation based on high and/or low outdoor temperatures.
• Display outdoor temperature on thermostat.
Outdoor temperature sensor should
be mounted:
• On side of building out of direct sunlight
(north side recommended).
• Above snow line.
• At least 3’ away from exhaust vents and
condensing lines.
• Using less than 300’ of wire.
• Do not route wires along 120 VAC lines.
For installations where it is difficult to wire the included 8052 outdoor temperature sensor, a Model 8056 wireless
outdoor sensor can be used. The Model 8056 module has two radio units, one that is placed on the equipment control
module as shown below, and a second radio that is placed outside. See the Model 8056 Installation Instructions for
detailed directions regarding installation.
Outdoor Sensor
INSTALLATION
LEAVING AIR TEMPERATURE SENSOR (OPTIONAL)
Leaving air temperature can be measured by attaching an 8052 sensor to the LAT terminals. The leaving air
temperature sensor measurement is displayed during the installer test for diagnostic purposes.
IMPORTANT
Do not mount the sensor in direct line-of-sight of the heat exchanger, cooling coils, or UV lights as this may cause
the sensor to report false temperature readings.
1. Locate the Aprilaire Model 8052 sensor in the supply trunk, after the heat exchanger and cooling coils. (See
shaded areas in figure below.)
2. Mount the sensor according to the installation instructions provided with the sensor.
3. Wire the sensor to the equipment control module LAT terminals.
LOCATE
SENSOR
IN SHADED
AREA.
RETURN AIR TEMPERATURE SENSOR (OPTIONAL)
Return air temperature can be measured by attaching an 8052 sensor to the RAT terminals. The return sensor must
be enabled in the installer setup menu. The return air temperature sensor provides protection in the event that the
equipment control module loses connection with the thermostat. In the event that the thermostat connection is lost,
the equipment control module will use the return air temperature sensor to maintain a temperature greater than 40°F
and less than 100°F.
1. Locate the Aprilaire Model 8052 sensor
in the return trunk.
2. Mount the sensor according to the
installation instructions provided with
the sensor.
3. Wire the sensor to the equipment
control module RAT terminals.

8 9
HVAC WIRING DIAGRAMS
CONVENTIONAL HEAT/COOL SINGLE TRANSFORMER (USE JUMPER)
W
W2
W3
Y
Y2
Y3
G
HC HP
EQ
3
C
RC
RH
L
G
O
Y2
Y
B
W2
W
R
C
TRANSFORMER
2nd HEATING
1st HEATING
THERMOSTAT
FAN
1st COOLING
2nd COOLING
2
1
3rd HEATING
3nd COOLING
CONVENTIONAL HEAT/COOL TWO TRANSFORMER (REMOVE JUMPER)
HEATING TRANSFORMER
COOLING TRANSFORMER
C
R
W
W2
B
Y
Y2
O
G
L
RH
RC
C
3
EQ
HPHC
G
Y3
Y2
Y
W3
W2
W
TRANSFORMER
THERMOSTAT
1
2
2nd COOLING
1st COOLING
FAN
1st HEATING
2nd HEATING
3rd HEATING
3rd COOLING
1R and C can be
powered from the
HVAC equipment
transformer or any
other constantly
powered 24VAC
source.
1
HVAC WIRING DIAGRAMS
HEAT PUMP SINGLE TRANSFORMER (USE JUMPER WIRE)
C
R
W
W2
B
Y
Y2
O
G
L
RH
RC
C
3
EQ
HPHC
G
Y3
Y2
Y
W3
W2
W
FAULT DETECT
REVERSING VALVE
THERMOSTAT
REVERSING VALVE
1
2
2nd COMPRESSOR
1st COMPRESSOR
FAN
1st HEATING
2nd HEATING
HEAT PUMP TRANSFORMER
HEAT PUMP TWO TRANSFORMER (REMOVE JUMPER WIRE)
THERMOSTAT
TRANSFORMER
W
W2
W3
Y
Y2
Y3
G
HC HP
EQ
3
C
RC
RH
L
G
O
Y2
Y
B
W2
W
R
C
HEAT PUMP TRANSFORMER
HEATING TRANSFORMER
1
FAULT DETECT
REVERSING VALVE
REVERSING VALVE
2nd HEATING
1st HEATING
FAN
1st COMPRESSOR
2nd COMPRESSOR
2
1
1R and C can be
powered from the
HVAC equipment
transformer or any
other constantly
powered 24VAC
source.

10 11
Note: Outputs are 24VAC dry contact. Refer to individual product installation instructions for more details.
INDOOR AIR QUALITY WIRING DIAGRAMS
INDOOR AIR QUALITY WIRING WITH SEPARATE TRANSFORMERS
INDOOR AIR QUALITY WIRING WITH A SINGLE TRANSFORMER
TRANSFORMER
TRANSFORMER
TRANSFORMER
VNT
DH
HUM
EAC
DH
DHnc
com
no DEHUMIDIFIER
NORMALLY
CLOSED DAMPER
HUMIDIFIER
PILOT RELAY FOR
120 VAC TO EAC
Note: Outputs are 24VAC dry contact. Refer to individual product installation instructions for more details.
no
com
nc
DH
DH
EAC
HUM
DH
VNT
TRANSFORMER
HUMIDIFIER
NORMALLY
CLOSED DAMPER
DEHUMIDIFIER
PILOT RELAY FOR
120 VAC TO EAC
POWER & RESET OPTIONS
The equipment control module is powered from 24VAC. The thermostat is powered from the equipment control
module. In the case of power loss the thermostat will maintain the clock for 24 hours. The thermostat has a memory
backup that saves the thermostat settings in case of power interruption.
The factory reset is located in the Installer Tools option of the Installer Menu. See Installer System Settings section
for details.
SETUP & TESTING
INSTALLER SETUP WIZARD
The first time the thermostat is powered up (or after a factory reset) it will enter the Installer Setup Wizard. All
installer settings can be set in this process. The installer settings are also accessible in the MENU by pressing the
Contractor Info button for 10 seconds.
Import USB settings will be the first screen
that you see (the button will be grayed out
until a USB drive is inserted).
• If you have a USB drive with installer setup
files on it, insert it into the USB connector
(on the lower left corner) to import a file.
• Or press skip to proceed with the Installer
Setup Wizard.
Note: Installer setup files can be created from
the Export Setup option found under Installer
Menu > Installer Tools > Export Setup.
The following tables contain the system settings and their details. Default settings are shown in bold. Some settings
are only available dependent upon the value of other settings.
General System Settings Table
System setting Description
Factory default setting
(bold) and setting range
Connection Type Selects if the thermostat connects with an automation
system or an Aprilaire account.
Automation System
Aprilaire Cloud
Installer Temperature Scale This selection only effects the installer setup menus. Fahrenheit
Celsius
Contractor Information Input Enter contractor’s contact information. Company, Phone, Email, Web
HVAC INSTALLER SYSTEM SETTINGS TABLES

12 13
SETUP & TESTING
Thermostat System Settings Table
System setting Description
Factory default setting
(bold) and setting range
Equipment Type Note: Equipment Type related settings will return to
defaults if this is changed.
Heat/Cool
Heat Pump
Control Setup Used to lockout heating or cooling outputs. (Heat/Cool
mode only.)
Heat & Cool
Heat Only
Cool Only
Heat Pump Auxiliary Type Selects auxiliary type. (Heat Pump mode only.) Gas/Oil Heat
Electric Heat
Fan Control In Heating Selects thermostat or equipment to control the fan in
heating. (Heat/Cool mode only.)
Gas/Oil Heat
Electric Heat
Number of Compressor Stages Select number of compressor stages. (Heat Pump mode
only.)
One
Two
Number of Auxiliary Heat Stages Select number of auxiliary heat stages. (Heat Pump
mode only.)
One
Two
Number of Stages of Heat Select number of heat stages. (Heat/Cool mode only.) One
Two
Three
Number of Stages of Cool Select number of cool stages. (Heat/Cool mode only.) One
Two
Three
Remote Temperature Sensor
Installed?
Select if the remote sensor is attached, and uses backup,
or is averaged with built-in.
No
Yes
Yes (fallback built-in)
Yes (average w/built-in)
Return Air Temperature Sensor
Installed?
Select if return air temperature sensor is attached or not. No
Yes
Outdoor Temperature Sensor
Installed?
Select if outdoor sensor is attached or not. No
Yes
Automation
Display Support Modules Select if support module values are displayed on
Monitored Climate screen under Status.
No
Yes
Number of Controlling Support
Modules Temp
Select number of sensors configured to be controlling
temperature.
0-8
Number of Controlling Support
Modules RH
Select number of sensors configured to be controlling
RH.
0-4
Schedule Enables or disables programmable schedule. Enabled
Disabled
Progressive Recovery Enables or disables progressive recovery. Enabled
Disabled
Display Away Button? Away allows the user to set the thermostat to a
predefined setpoint using a single button press.
The predefined setpoints can be selected in the User
Settings.
No
Yes
Display Heat Blast Button? Select if the Heat Blast button is displayed. No
Yes
Blast Offset Amount of heating when Heat Blast is initiated. 3°F (1.5°C)
4°F (2°C)
5°F (2.5°C)
HVAC INSTALLER SYSTEM SETTINGS TABLES (CONTINUED)
Thermostat System Settings Table (continued)
System setting Description
Factory default setting
(bold) and setting range
Extended Fan – Heat Extends fan operation after heat call ends. Disabled
Enabled
Extended Fan – Cool Extends fan operation after cool call ends. Disabled
Enabled
Auto Changeover Enable or disable Auto Changeover mode. Disabled
Enabled
DeadBand Auto Changeover mode deadband. 3°F (1.5°C)
2 to 9°F (1 to 4.5°C)
Auto Changeover Time Minimum time between heating and cooling calls. 4 Minutes
1 to 5 Minutes
Internal Temperature Sensor
Offset
Field adjustment of controlling temperature sensors. 0°F (0°C)
-4 to 4°F (-2 to +2°C)
Internal RH% Sensor Offset Field adjustment of internal RH sensor. 0
-5 to 5
Equipment Minimum On Time Minimum on time for heating and cooling. 2 Minutes
1 to 5 Minutes
Heating Minimum Off Time Minimum off time for heating. 2 Minutes
1 to 5 Minutes
Compressor Minimum Off Time Minimum off time for compressor protection. 5 Minutes
1 to 5 Minutes
Outdoor Temperature High
Balance Point
Enable or disable high balance point (Available if ODT
is installed.)
Enabled
Disabled
Select High Temperature Balance
Point
If outside temperature is above the high balance point
the aux heat operation is not allowed. (Available if high
balance point is enabled.)
65°F (14.5°C)
0 to 80°F (-18 to 22°C)
Outdoor Temperature Low
Balance Point
Enable or disable low balance point (Available if ODT is
installed.)
Enabled
Disabled
Select Low Temperature Balance
Point
If outside temperature is below the low balance point
the compressor operation is not allowed. (Available if
low balance point is enabled.)
20°F (-8°C)
0 to 60°F (-18 to 12°C)
Stage Rate Accumulation of equipment run time in staging
determination.
Enabled
Disabled
Factor 1 = more rapid staging of equipment (comfort),
5 = slower staging of equipment (economy).
2
1 to 5
First Stage Differential First stage differential. 1°F (0.5°C)
1 to 9°F (0.5 to 4.5°C)
Second Stage Differential Second stage differential. 1°F (0.5°C)
1 to 9°F (0.5 to 4.5°C)
Third Stage Differential Third stage differential. 1°F (0.5°C)
1 to 9°F (0.5 to 4.5°C)
Fourth Stage Differential Fourth stage differential. 1°F (0.5°C)
1 to 9°F (0.5 to 4.5°C)
Service HVAC Reminder The period for displaying the “HVAC Service reminder”
message.
Disabled
Enabled
Number of Months for Recurrence Select number of months for displaying reminder. 12 Months
1 to 12 Months
SETUP & TESTING
HVAC INSTALLER SYSTEM SETTINGS TABLES (CONTINUED)

14 15
SETUP & TESTING
The following tables contain the Indoor Air Quality system settings and their details. Default settings are shown in
bold. Some settings are only present dependent upon the value of other settings.
The use of an outdoor temperature sensor (recommended) enables additional Indoor Air Quality functionality.
Please refer to the Model 8840 Owner’s Manual for further information about thermostat features.
Note: Refer to manuals for humidifier, dehumidifier, air cleaner, and ventilation products for recommended
installation and operation.
Humidifier System Settings Table
System setting Description
Factory default setting
(bold) and setting range
Humidifier Installed? Selects if a humidifier is installed. Yes/On HVAC is
used for applications where the humidifier is installed
on the HVAC duct. Yes/Standalone is used for
application where the humidifier is independent of
the HVAC system. (If set to no, no other humidifier
settings will be available.)
No
Yes/On HVAC
Yes/Standalone
Display Button? Note: Only available if Humidifier Installed is set
to No.
Yes
No
Outdoor Temperature Sensor Installed? Select if outdoor sensor is attached or not. No
Yes
Humidifier Mode Selects auto or manual mode. Auto mode controls
humidity based on the humidity setting and outdoor
temperature. Manual mode controls humidity based
on the %RH setpoint. (Auto mode is only available if
outdoor sensor is set to Yes or Automation.)
Auto
Manual
Allowed Humidifier Operation Selects when humidification is allowed to occur
relative to heating and fan operation. Without Fan
allows humidification to occur without the HVAC fan.
This option should only be used when the humidifier
is independent of the HVAC system. Note: Without
Fan is only available when Humidifier Installed is
set to Yes/Standalone.
Heat Only
Heat or Fan
Forces Fan
Without Fan
CAUTION: When Humidifier Operation is set to Without Fan the thermostat will turn on humidification
without energizing the HVAC fan. Do not select this option when the humidifier is installed on the HVAC duct.
Without airflow moisture can accumulate in the duct resulting in significant damage.
Humidity Deadband Select the minimum difference between the
humidifier and dehumidifier setpoints. (Only available
if both a humidifier and dehumidifier are installed.)
10%
10 to 20%
Humidifier Reminder Selects when the “Change Water Panel” message is
displayed.
Off
300h Valve
600h Valve
1 per season
2 per season
Single or First Reminder Appears Determines the month the first (or only) “Change
Water Panel” message is displayed.
October
November
December
January
February
March
April
May
June
July
August
September
INDOOR AIR QUALITY SYSTEM SETTINGS TABLES
SETUP & TESTING
Dehumidifier System Settings Table
System setting Description
Factory default setting
(bold) and setting range
Dehumidifier Type Installed? Selects if a dehumidifier is installed. (If set to None,
no other dehumidifier settings will be available.)
None
Whole Home
Air Conditioner
Display Button? Note: Only available if Dehumidifier Installed is set
to None.
Yes
No
Disable Dehumidification During
Cooling?
Selects if a dehumidifier is disabled during a cooling
call.
Yes
No
Dehumidifier Forces Fan? Selects if dehumidification can turn on the fan. Yes
No
Dehumidifier Overcooling Limit Selects the amount of overcooling that can occur for
dehumidification. (Only available if dehumidifier type
is set to Air Conditioning.)
1°F (0.5°C)
2°F (1°C)
3°F (1.5°C)
Dehumidifier Reminder The period for displaying the “Dehumidification
Service Reminder” message.
Disabled
Enabled
Number of Months for Recurrence Select number of months for displaying reminder. 12 Months
1 to 12 Months
Dehumidify in Vacation Hold? Selects if dehumidification with the air conditioner is
done in vacation mode.
No
Yes
Vacation Hold Low Temperature Limit Sets the lowest temperature the air conditioner
will cool to, to meet RH setpoint in Vacation Mode.
(Only available if dehumidifier type is set to Air
Conditioning.)
75°F (24°C)
70 to 85°F (21 to 29.5°C)
Humidity Deadband Select the minimum difference between the humidifier
and dehumidifier setpoints. (Only available if both a
humidifier and dehumidifier are installed.)
10%
10 to 20%
System setting Description
Factory default setting
(bold) and setting range
Second Reminder Appears Determines the month the second “Change Water
Panel” message is displayed.
October
November
December
January
February
March
April
May
June
July
August
September

16 17
SETUP & TESTING
Fresh Air System Settings Table
System setting Description
Factory default setting (bold)
and setting range
Fresh Air Vent Installed Selects if ventilation is installed. (If set to No, no other
ventilation settings will be available.)
No
Yes
Display Button? Note: only available if Fresh Air Installed is set to No. Yes
No
Fresh Air Setup Type Selects if ventilation is configured through the Code setup
or Comfort. Comfort setup has more lockout options. Code
setting ensures missed lockout time is made up.
Comfort
Code
Number of Bedrooms Selects the number of bedrooms to be used for the Calculated
Minutes per Hour.
3 Bedrooms
1 to 10 Bedrooms
Home Size Selects the size of the home to be used for the Calculated
Minutes per Hour.
2500 SQ FT
500 to 7500 SQ FT
Measured CFM Selects the ventilation CFM to be used for the Calculated
Minutes per Hour.
110 CFM
30 to 250 CFM
Calculated Minutes
per Hour
Displays the Fresh Air Time calculated. None
Range 6 to 60 Minutes
Override Manual adjustment of Calculated Minutes per Hour. (Calculated Minutes per Hour)
Range 6 to 60 Minutes
Outdoor Temperature
Sensor Installed?
Select if outdoor sensor is attached or not. No
Yes
Enable High Vent RH
Limit
Selects if ventilation is disabled if the indoor RH exceeds the
indoor RH limit. (Only available if Fresh Air Setup is set to
Comfort.)
Yes
No
High Vent RH Limit Sets the ventilation indoor RH lockout limit. (Only available if
Enable High Vent RH Limit is set to Yes.)
55%
45% to 70%
Enable Low Vent RH
Limit
Selects if ventilation is disabled if the indoor RH exceeds the
indoor RH limit. (Only available if Fresh Air Setup is set to
Comfort.)
No
Yes
Low Vent RH Limit Sets the ventilation indoor RH lockout limit. (Only available if
Enable Low Vent RH Limit is set to Yes.)
20%
10% to 30%
Enable High Vent
Temperature Limit
Enables high ventilation temperature lockout limit. (Only
available if Outdoor Sensor is set to Installed or Automation.)
No
Yes
High Vent Temperature
Limit
Sets high ventilation temperature lockout limit. (Only available
if Enable High Vent Temperature Limit is set to Yes.)
100°F (38°C)
85°F to 105°F (29°C to 41°C)
System setting Description
Factory default setting (bold)
and setting range
Enable Low Vent
Temperature Limit
Enables low ventilation temperature lockout limit. (Only
available if Outdoor Sensor is set to Installed or Automation.)
No
Yes
Low Vent Temperature
Limit
Sets low ventilation temperature lockout limit. (Only available
if Enable Low Vent Temperature Limit is set to Yes.)
10°F (-12°C)
-10°F to 40°F (-24°C to 6°C)
HVAC Fan with Vent Selects if ventilation forces the fan on. (Yes with high and low
limits is only available if Outdoor Sensor is set to Installed or
Automation.)
Yes
Yes with high and low limits
No
Enable High Mixing
Temperature
Enables high mixing temperature. (Only available is HVAC Fan
with Vent is set to Yes with high and low limits.)
No
Yes
High Mixing
Temperature
Sets the high mixing temperature. (Only available if Enable
High Mixing Temperature is set to Yes.)
80°F or (26°C)
60°F to 105°F (14°C to 41°C)
Enable Low Mixing
Temperature
Enables low mixing temperature. (Only available is HVAC Fan
with Vent is set to Yes with high and low limits.)
No
Yes
Low Mixing
Temperature
Sets the Low mixing temperature. (Only available if Enable
Low Mixing Temperature is set to Yes.)
40°F (6°C)
0°F to 50°F (-18°C to 12°C)
Fresh Air Service
Reminder
The period for displaying the “SERVICE FRESH AIR” message. OFF
1 to 12 months or “OFF” to disable
SETUP & TESTING
INSTALLER SYSTEM TEST
The Installer Test can be accessed from
the Installer Menu. All equipment outputs
that are configured in the installer settings
can be turned on and off for testing
equipment. Minimum on and off times are
not enforced while in this mode.
Air Cleaning System Settings Table
System setting Description
Factory default setting
(bold) and setting range
Air Cleaner Installed? Selects if an air cleaner is installed. (If set to No, no other
air cleaner settings will be available.)
No
Yes
Display Button? Note: Only available if Air Cleaning Installed is set to No. Yes
No
Air Cleaner Reminder The period for displaying the “Change Air Filter” message. Disabled
Enabled
Number of Months for Recurrence Select number of months for displaying reminder. 12 Months
1 to 12 Months

18 19
CONNECT TO A NETWORK USING
A BROWSER
STEP 2: Connect to the thermostat using a
computer or mobile device.
On your computer or mobile device, scan for
available networks. The thermostat should appear
as APRILAIRE8840 followed by a unique identifier,
corresponding to the last 6 digits of the MAC address.
Connect to the thermostat you want to configure.
If you are installing multiple thermostats, the MAC
address of each thermostat will be displayed on the
Wi-Fi Settings screen, and can be found on the back of
the thermostat.
STEP 3: Configure the thermostat to connect
to the Wi-Fi network.
Open a web browser on your computer or mobile device.
In the browser enter:
http://192.168.1.99/index.html
In the web browser interface select the network you
want to connect the thermostat to, and enter the
network’s security credentials.
STEP 4: Verify the thermostat is connected to
the Wi-Fi network.
Once all the required information is entered in the web
browser interface, the thermostat will connect to the
Wi-Fi network you selected. After the thermostat is
connected to the Wi-Fi network, the thermostat will
display the radio bars based on the Wi-Fi signal strength.
Note: If you are not using the thermostat with a home
automation system, but are instead using an Aprilaire
account to communicate with the thermostat, refer to
Wi-Fi Thermostat App User Guide and then Start Up
Guide on my.aprilaire.com for instructions on connecting
to Wi-Fi and registering to an Aprilaire account.
The 8840 can be connected to a Wi-Fi network either at the thermostat or another Wi-Fi device with a web browser.
STEP 1: Verify the thermostat is in Wi-Fi Connection Mode.
The thermostat by default will be in Wi-Fi Connection Mode. To confirm that the thermostat is in Wi-Fi Connection
Mode, verify that the radio bars on the thermostat are strobing as shown below.
Note: If the thermostat is not in Wi-Fi Connection Mode, refer to the online owner’s manuals found at my.aprilaire.com.
CONNECT TO A NETWORK USING
THE THERMOSTAT
STEP 2:
Navigate to the Connect without App screen:
Menu > Wi-Fi Settings > Advanced > Connect
without App.
STEP 3:
Select a network from the list of scanned networks.
STEP 4:
Enter a password and press Done.
STEP 5:
Press Done on the Credentials screen to connect.
QUICK REFERENCE TO CONTROLS & DISPLAY
HOME SCREENWI-FI SETUP
MAIN MENU
NOTE: SCREEN BRIGHTENS AFTER FIRST TOUCH.
OUTDOOR
TEMPERATURE
& HUMIDITY
(IF INSTALLED)
SET SCREEN
BRIGHTNESS
AND SCREEN
SAVER
HEATING AND
COOLING
EQUIPMENT
STATUS
SET DATE & TIME
HOLD MENU
& STATUS
CONNECT TO
WI-FI NETWORKS
SYSTEM MODE
SELECTION
SET SCHEDULE
DETAILED
EQUIPMENT STATUS
HEAT BLAST MODE &
STATUS (IF INSTALLED)
WEATHER FORECAST
& ALLERGY REPORT
VIEW CONTRACTOR
INFORMATION OR
ACCESS INSTALLER
MENU WITH
10 SECOND PRESS
& HOLD
ACTIVE ALERTS &
ALERT SETTINGS
SET VACATION
HOLDS
CURRENT SCREEN
RELATED HELP
MAIN MENU
HUMIDIFIER AND
OR DEHUMIDIFIER
INDOOR AIR
QUALITY SCREEN
& SIMPLE STATUS
AIR CLEANING
INDOOR AIR
QUALITY SCREEN
& SIMPLE STATUS
COOL SETTING CURRENT DATE AND TIME
(AUTOMATICALLY UPDATED IF
CONNECTED TO INTERNET)
WI-FI INDICATOR
(STROBES IN
SETUP MODE)
FRESH AIR INDOOR
AIR QUALITY
SCREEN & SIMPLE
STATUS
TEMPERATURE
SCALE, LOCKOUTS,
AWAY MODE
SETTING
(IF ENABLED)
AWAY MODE &
STATUS (IF INSTALLED)
FAN MODE
SELECTION
CLEAN DISPLAY
(TOUCHSCREEN
IS OFF FOR
30 SECONDS)
ROOM TEMPERATURE
& HUMIDITY
HEAT SETTINGTHERMOSTAT NAME
SETUP & TESTING

20 21
INSTALLER MENU
USB SETTINGS
FILE IMPORT, ETC
THERMOSTAT &
HVAC SYSTEM
CONFIGURATION
HUMIDIFIER
CONFIGURATION
DEHUMIDIFIER
CONFIGURATION
EQUIPMENT
OUTPUT TESTS
IMPORT/EXPORT
USB INSTALLER
SETTINGS FILES,
FACTORY RESET
VENTILATION
CONFIGURATION
AIR CLEANER
CONFIGURATION
QUICK REFERENCE TO CONTROLS & DISPLAY
POWER/STATUS – On solid during normal operation. Flashes
when connection to the thermostat is lost and at power-up while
the thermostat connection is being established.
HEATING – On when heating outputs are active.
COOLING – On when cooling outputs are active.
FAN – On when fan output is active.
HUMIDIFIER – On when humidifier output is active.
DEHUMIDIFIER – On when dehumidifier output is active.
VENTILATION – On when ventilation output is active.
AIR CLEANING – On when air cleaner output is active.
EQUIPMENT CONTROL MODULE LEDs
THERMOSTAT FEATURES
• Remote access and control over Wi-Fi.
• Indoor air quality control.
– Humidification automatic or manual control.
– Dehumidification.
– Event-Based™air cleaning.
– Ventilation with temperature and humidity limits.
• Temperature control.
• Heat Blast®raises the room temperature 3°F to 5°F.
• One touch Away.
• Support for optional wireless outdoor temperature
sensor.
• Large touch screen with adjustable backlight.
• 7 day programmability.
• Displays room temperature, room humidity,
temperature setting, and optional outdoor temperature.
• Air filter, humidifier, dehumidifier, and HVAC service
reminders.
• Programmable fan control with fan circulation mode.
• Easy to use temperature control can override program
schedule at any time.
• Progressive recovery ensures proper temperature at
the start of a program event.
• Built in compressor protection prevents damage to
your equipment.
• System test mode.

22 23
TROUBLESHOOTING
DISPLAY IS BLANK
If Power LED is not illuminated at the equipment
control module check the following:
• Check circuit breaker and reset if necessary.
• Make sure power switch at heating & cooling
system is on.
• Make sure furnace door is closed securely.
HEATING SYSTEM DOES NOT RESPOND
(“HEATING” APPEARS ON SCREEN)
• Check for 24VAC at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the heating
equipment to find the cause of the problem.
• Check for 24VAC between the heat terminal (W)
and the transformer common. If 24VAC is present,
the thermostat is functional. Check the heating
equipment to find the cause of the problem.
• Check for loose or broken wires between the
thermostat and the heating equipment.
COOLING SYSTEM DOES NOT RESPOND
(“COOLING” APPEARS ON SCREEN)
• Check for 24VAC at the equipment on the secondary
side of the transformer between power and
common. If voltage is not present, check the cooling
equipment to find the cause of the problem
• Check for 24VAC between the cooling terminal (Y)
and the transformer common. If 24VAC is present,
the thermostat is functional. Check the cooling
system to find the cause of the problem.
• Check for loose or broken wires between the
thermostat and the cooling equipment.
FAN DOES NOT TURN ON IN A CALL FOR HEAT
• Check Installer Setting Fan Control In Heating /
Heat Pump Auxiliary Type, to make sure the fan
control is properly set to match the type of system.
HEAT PUMP ISSUES COOL AIR IN HEAT MODE,
OR WARM AIR IN COOL MODE
• Check wiring at the terminal block to confirm the
reversing valve is connected to the proper terminal.
O is active in cooling and B is active in heating.
HEAT/COOL BOTH ON AT SAME TIME
• Check Installer Setting Equipment Type, to make
sure it is set to match the installed heating/cooling
equipment.
• Check to make sure heating and cooling wires are
not shorted together.
HEATING EQUIPMENT IS RUNNING IN
COOL MODE
• Check Installer Setting Equipment Type, to make
sure it is set to match the installed heating/cooling
equipment.
“HEATING” IS NOT DISPLAYED
• Check Installer Setting Control Setup is set
correctly.
• Change the System Mode to Heat, and set
the temperature level above the current room
temperature.
“COOLING” IS NOT DISPLAYED
• Check Installer Setting Control Setup is set
correctly.
• Change the System Mode to Cool, and set
the temperature level below the current room
temperature.
Control
Outdoor, Remote, Leaving and Return temperature sensor Maximum distance: 300 feet
Room temperature measurement Display range: 32° to 99°F (0° to 40°C)
Return and Leaving temperature measurement Display range: -40° to 160°F (-40° to 71°C)
Outdoor temperature measurement Display range: -40° to 130°F (-40° to 55°C)
Setpoint temperature range Heat: 40° to 90°F (4° to 32°C)
Cool: 50° to 99°F (10° to 37°C)
Setpoint humidity range Humidification: 10% to 50% R.H.
Dehumidification: 40% to 90% R.H.
SPECIFICATIONS
Electrical
Operating voltage 24VAC (18 – 30VAC)
Current Maximum: 2.5A (total), 1.0A (single output)
Maximum surge current: 5A
Environment
Temperature (shipping) -30° to 150°F (-34° to 65°C)
Temperature thermostat (operating) 32° to 120°F (0° to 48°C)
Temperature equipment control module (operating) 32° to 158°F (0° to 70°C)
Relative humidity Operating: 5% to 90% R.H. (non-condensing)

P.O. Box 1467 • Madison, WI 53701-1467 • Phone: [phone] • Fax: [phone]
www.aprilairepartners.com
61001172 2.17
B2206592D
U.S. Patent Numbers 8,146,376, 8,596,078 and other patents pending.
© 2017 Aprilaire – A division of Research Products Corporation