Aprilaire 8870 User manual

Installation Instructions
MODEL 8870
These instructions are for connecting
the Thermostat to the HVAC equipment.
To connect communication features,
please reference the Communicating Thermostat
System Installation Manual.

INSTALLATION INSTRUCTIONS MANUAL
TABLE OF CONTENTS
Warning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Model 8870 Thermostat Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
1. HVAC System Pre-Installation Check List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. What’s In The Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Select The Thermostat Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Disassembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Mount Base To Wall . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Setting The Dip Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Wiring The Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8. Reassemble The Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9. HVAC System Check Out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10. Optional HVAC Set-Up Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
11. To Access The HVAC Set-Up Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Wiring Diagrams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16 – 22
Note Pages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23 – 25
© Research Products Corporation 2001

1
READ COMPLETE SAFETY & INSTALLATION
INSTRUCTIONS BEFORE STARTING
WARNING
1. 120-volts may cause serious injury from electrical shock. Disconnect
electrical power to the furnace and air conditioner before starting installation.
This thermostat is not a 120-volt (line voltage) device.
2. Improper installation may cause serious injury from electrical shock. This
product must be installed by a qualified heating and air conditioning contractor
in accordance with NEC Standards and applicable local and state codes.
3. Mercury is toxic and may be hazardous to health. Any replaced thermostats
containing mercury must be disposed of properly. Contact local authorities
for disposal information.

MODEL 8870 THERMOSTAT SPECIFICATIONS:
Control Voltage 24V AC ±20%
Switched Voltage 18 – 30V AC
Maximum Operating Current 2.0A total at rated voltage, through all outputs.
1.0A through any one output.
Maximum Surge Current 2.0A
Control Accuracy ±1.0°F
Control Range 40° – 90°F
Operating Range 32° – 99°F
1. HVAC SYSTEM PRE-INSTALLATION CHECK LIST
Before getting started determine what type of heating system is/will be installed in the house.
Then use Table 1 to determine if the proper numbers of wires are available depending on the
HVAC System. Additional wires will be required for communication system.
TABLE 1
APPLICATION # OF HVAC WIRES DIAGRAM PAGE #
Single Stage Furnace & AC 5 1 16
Two Stage Furnace & Two Stage AC 7 2 17
Roof Top Unit (Two Stage Heat & Two Stage Cool) 7 3 18
Boiler with AC (Two Transformers) 5 4 19
Single Stage Heat Pump 7 5 20
Two Stage Heat Pump 9 6 21
First Stage Radiant Floor Heat
Second Stage Furnace One Stage of Cooling 6 7 22
2

2. WHAT’S IN THE BOX
• Thermostat (Figure 1): front panel, cover, and base
• Installation Manual
• Owners Manual
• Hardware bag: screws and wall anchors
FIGURE 1
3. SELECT THE THERMOSTAT LOCATION
Determine if the thermostat will be operating alone, or with remote temperature sensors.
If the unit is stand-alone there are certain measures that must be taken to ensure accurate
temperature control.
STAND-ALONE THERMOSTAT MOUNTING CRITERIA:
• Mount on an interior wall.
• In a room frequently occupied.
• At least 18 inches from any outside wall.
• Approximately 5 feet above the floor. Check with local building codes for height
requirements in commercial requirements.
3
Front Panel
Cover
Base

DO NOTlocate the thermostat:
• Behind doors, in corners or other dead air spaces.
• In direct sunlight or near lamps, appliances or other sources of radiant heat.
• On an outside wall or wall exposed to an unconditioned space (i.e. garage, etc.).
• In the flow path of a supply register, in stairways or near outside doors.
• On a wall where concealed pipes and/or ductwork will affect the thermostat.
• Near sources of electrical interference such as arcing relay contacts.
WITH REMOTE TEMPERATURE SENSORS
Follow the guidelines for placement of the sensors and locate the thermostat indoors where
operating range (see specs) will not be violated (i.e. do not install in a cold garage or hot
equipment room). See the sensor installation literature for additional details.
4. DISASSEMBLY
No tools required – use hands to pull the front
panel off of the base (Figure 2). While holding
the base of the thermostat, apply pressure to the
base of the latch with your thumb (Figure 3).
Both sides have a latch, but it is easiest to
unlatch one side at a time.
CAUTION: Loss of internal programs may result from static discharge to thermostat circuit
board. Installer must touch a grounded metal object before handling the circuit board.
FIGURE 2
4

FIGURE 3
5. MOUNT BASE TO WALL
There are four screw holes located on the base of the thermostat; two are for a junction box
mounting, along with two for alternate mounting spacing. Use one of the holes on the top
and one on the bottom.
a) Place the base over the wire hole opening in the wall; level the base and mark the screw
hole mounting locations (leveling required for appearance only).
b) If using supplied wall anchors, drill 3/16" hole in the center of the marked locations and
tap in the wall anchors. If using the supplied screws only, drill a 3/32" hole in the center
of the marked locations.
c) Fasten the base to the wall with the supplied screws.
d) Seal wire entry using caulk, drywall putty or insulation.
CAUTION: Minimize wire entry hole size and seal – drafts from
inside the wall could affect temperature readings.
5
Press
base here
Latch

6
6. SETTING THE DIP SWITCHES
Set the dip switches located on the thermostat circuit
board (Figure 4) according to the application needs (Table 2).
Figure 4 shows what each switch corresponds to depending on posi-
tion. Switch one should be set in the “OFF Servant” position unless you plan to
broadcast readings from remote temperature sensors to other thermostats in the
system when there is no communication system in place.
FIGURE 4

TABLE 2
APPLICATION SWITCH #1 SWITCH #2 SWITCH #3 SWITCH #4
Single Stage Furnace & AC Servant Fossil Single H/C
Two Stage Furnace & Two Stage AC Servant Fossil Multi H/C
Roof Top Unit (Two Stage Heat & Two Stage Cool) Servant Fossil Multi H/C
Boiler with AC (Two Transformers) Servant Fossil Single H/C
Single Stage Heat Pump Servant Electric Single HT. Pump
Two Multi-stage Heat Pump Servant Electric Multi HT. Pump
First Stage Radiant Floor Heat
Second Stage Furnace One Stage of Cooling Servant Fossil Multi H/C
7. WIRING THE THERMOSTAT
a) Strip 1/4" of insulation from each wire to be used. Figure 5 shows all wiring
terminal definitions.
b) Secure wires into the terminals on the base according to the appropriate wiring diagram
(Table 3). Use color-coding practices (i.e. white wire to W terminal) whenever possible.
TABLE 3
APPLICATION DIAGRAM PAGE #
Single Stage Furnace & AC 1 16
Two Stage Furnace & Two Stage AC 2 17
Roof Top Unit (Two Stage Heat & Two Stage Cool) 3 18
Boiler with AC (Two Transformers) 4 19
Single Stage Heat Pump 5 20
Two Stage Heat Pump 6 21
First Stage Radiant Floor Heat
Second Stage Furnace One Stage of Cooling 7 22 7

8
FIGURE 5

9
7. WIRING THE THERMOSTAT (Cont.)
c) Check each wire to ensure it is securely fastened, not broken, and exposed wires
are not touching.
8. REASSEMBLE THE THERMOSTAT
No tools required – line up pins on circuit board with the corresponding terminal blocks.
Use your hands to push the front panel securely to the mounted base.
CAUTION: Loss of internal programs may result from static discharge to thermostat circuit
board. Installer must touch a grounded metal object before handling the circuit board.
9. HVAC SYSTEM CHECK OUT
HVAC installer may need to connect 24V AC to the R and C terminals to check HVAC
operation. If the automation system is to be installed after the HVAC installation, leave the
R and C terminals connected to ensure the HVAC system operates. If the automation system
is installed before the HVAC wiring, then do not connect HVAC wires to R and C.
When the thermostat is first turned on all of the graphics of the main LCD are momentarily
displayed; this will look like Figure 6.

10
Mode Fan Enter
SCROLL/
SET-UP
BUTTONS
ADJUST
BUTTONS
MESSAGEDISPLAY
MAINDISPLAY
REMOTE
NETWORK
OVERRIDE
COOL
HEATEM. -AUX
DEHUMHUMIDIFY
BIAS
DIF1
DIF2
C
FAN
RH ON
ROOM
F
C
F
R
O
FIGURE 6
Use the Check Out Procedure (Figure 7, on the next page) to determine
if the thermostat is controlling the HVAC equipment.

11
CHECK-OUT PROCEDURE
CAUTION:The following check-out procedure will turn the heating and cooling equipment on and off. Do not
operate in cooling at low outdoor temperatures. Do not operate in heating at high outdoor temperatures.
Refer to equipment manufacturer specifications for safe operating temperatures.
STEP LOOK FOR... PRESS
2
3
NOTES AND REACTION
Press the Mode button repeatedly untill OFF appears on the display.
FAN FAN ON
Press the Fan button. System blower should start and FAN ON appears
on display. Press again to stop.
MODE
Press the Mode button until COOL appears along with the current
cool setting.
4
Use the down arrow to lower the set point 3°F below room temp. In 5-10
seconds the first stage of cooling begins and the COOL icon begins to
flash. If there is a second stage it will begin in 4 minutes.
7
6
MODE
Press the Mode button until HEAT appears along with the current
heat setting.
Use the up arrow to raise the set point 3°F above room temp. In 5-10
seconds the first stage of heating begins and the HEAT begins to flash.
If there is a second stage it will begin in 4 minutes.
1
5
Press the Mode button until OFF appears on the display.
You must change the mode to override the Minimum On time delays.
9
COOL
COOL
HEAT
HEAT
HEAT -AUX
7A
"-AUX" comes on when the auxiliary heat terminal (W1) is energized.
The LED on top of thermostat will illuminate.
8
Press the Mode button until OFF appears on the display. During Check-out,
change the mode to override the Minimum On time delays.
EM. HEAT
Press Mode button until EM. HEAT appears on display.
Repeat step 7 to verify Emergency Heat operation.
>
>
HEAT PUMP ONLY
HEAT PUMP ONLY
MODE
MODE
MODE
MODE
FIGURE 7

10. OPTIONAL HVAC SET-UP FEATURES
There are a number of HVAC features that can be configured for the particular application.
These include temperature control options, display options and high/low balance points
(heat pumps only).
A) TEMPERATURE CONTROL OPTIONS
1. OFFSET –allows the user to offset the displayed room temperature ±3°F from true
temperature. This thermostat is calibrated to be within ±1°F of true temperature.
2. 1ST STAGE DIFFERENTIAL –determines the level of control and consequently the cycle
rate. Adjustable between 0.5°F and 2.0°F, this is the value above/below the set point
that the temperature must rise (fall) to start the cooling (heating). It is also the value
below (above) the set point that the temperature must fall (rise) for the cooling (heating)
to stop. For example, if the temperature setting was 70°F and the 1st stage differential
was set at 0.5°F, in the heat mode the heat would come on at 69.5°F and stay until the
temperature was 70.5°F. A small differential will result in a tighter control, but more
heating/cooling cycles.
3. 2ND STAGE DIFFERENTIAL –again adjustable between 0.5°F and 2.0°F, this also
determines the level of control by determining when to use the 2nd stage of heating or
cooling. It can also be used to keep 2nd stage cooling from coming on too soon when
1st stage is acting to control temperature levels or to keep costly auxiliary heat from
coming on too soon when the heat pump is sufficient.
B) BALANCE POINTS
These values are adjustable, but are only used by the thermostat when it has been
configured to operate as a heat pump and when a remote outdoor temperature sensor,
with address #1, is wired to the thermostat.
12

B) BALANCE POINTS (Cont.)
1. LOW BALANCE POINT –the outdoor temperature below which compressor terminals
will not be energized.
2. HIGH BALANCE POINT –the outdoor temperature above which the auxiliary heat terminal
will not be energized in the HEAT mode (does not effect Emergency Heat operation).
C) DISPLAY OPTIONS
1. TEMPERATURE SCALE –all temperatures displayed including room temperatures and
set points can be °F or °C.
2. SHOW TEMPERATURE SET POINTS ALWAYS –keeps the temperature settings visible on
the display at all times.
3. SHOW TEMPERATURE SET POINTS ONLY IF CHANGED –displays the temperature
settings (heat and/or cool) only when the user changes them. The first press of either
the up or down adjust buttons will display the settings.
4. SHOW DATE AND TIME –the message display will, by default, scroll three messages
showing the status of the mode, fan and equipment outputs. A fourth date and time can be
added to this list. However, the automation system must transmit the time and date to
the thermostat at least once a day. If the automation system is not capable of doing
this, the date and time can be configured not to show.
11. TO ACCESS THESE HVAC SET-UP FEATURES
When first powered up, the message display will scroll through the current mode status,
fan status, and heating/cooling output status. This is referred to as Passive Display because
you do not interact with it. To get into the Set-Up Menu, press the Enter button
and Mode button at the same time. This is referred to as User Interactive Display, as the user
navigates through various menu and sub-menu selections to change variables. 13

14
FIGURE 8
11. TO ACCESS THESE HVAC
SET-UP FEATURES (Cont.)
Set-Up is menu driven but only one menu
item is visible at a time. Figure 8 shows
the entire Main Menu. Selecting any one
of the Main Menu items (by pressing the
Enter button) will enter a corresponding
Sub-Menu. Figure 8 also shows the
Temperature Set-Up, Balance Points
Set-Up and Display Set-Up sub-menus
expanded. The Scroll Up and Scroll
Down buttons are used to move
between menu items or change values.
The Enter button is used to select
a menu item or enter a value. When in
Thermostat Set-Up, if none of the three
navigation buttons are pressed in 5 min-
utes, the display will return to Passive
Display. Again, you will only see one
menu item at a time.

15
FIGURE 8 (Cont.)

IMPORTANT!
The B terminal is for
reversing valve-heat.
DO NOT connect the
B terminal to
common side of
transformer.
NOTE: HVAC installer may need to connect 24V AC
to the R and C terminals to check the HVAC operation.
If the automation system is to be installed after the
HVAC installation, leave the R and C terminals connected
to ensure the HVAC system operates. If the automation
system is installed before the HVAC wiring, then DO NOT
connect HVAC wires to R and C.
FAN
RELAY 1ST
STAGE
HEAT
R
ONE-STAGE FURNACE
C
G
W1
Y1
1ST STAGE
COOL
120
VAC
24
VAC
1ST
STG
COOL
ONE-STAGE AIR
CONDITIONER
Y1
C
G
Y1
W1
Y2
W2
RH
RC
O
APRILAIRE MODEL
8870 THERMOSTAT
B
C
RSB
RSR
RSC
R
RSA
B+
A-
A+
B-
REF
SEE
NOTE
24V FIELD WIRING
FACTORY WIRING
OPTIONAL 24V
FIELD WIRING (SEE NOTE)
L2
L1
COMMUNICATION
TERMINALS
REMOTE
SENSOR(S)
16
DIAGRAM 1 – SINGLE STAGE FURNACE AND AC

FAN
RELAY
2ND
STAGE
HEAT
1ST
STAGE
HEAT
R
TWO-STAGE FURNACE
C
G
W1
Y1
W2
Y2
1ST STAGE
COOL
2ND STAGE
COOL
L1
L2
120
VAC
24
VAC
1ST
STG
COOL
2ND
STG
COOL
TWO-STAGE AIR
CONDITIONER
Y1
C
Y2
IMPORTANT!
The B terminal is for
reversing valve-heat.
DO NOT connect the
B terminal to
common side of
transformer.
G
Y1
W1
Y2
W2
RH
RC
O
APRILAIRE MODEL
8870 THERMOSTAT
COMMUNICATION
TERMINALS
B
C
RSB
RSR
RSC
R
RSA
B+
A-
A+
B-
REF
REMOTE
SENSOR(S)
NOTE: HVAC installer may need to connect
24V AC to the R and C terminals to check the
HVAC operation. If the automation system is
to be installed after the HVAC installation,
leave the R and C terminals connected to ensure
the HVAC system operates. If the automation
system is installed before the HVAC wiring,
then DO NOT connect HVAC wires to R and C.
SEE
NOTE
24V FIELD WIRING
FACTORY WIRING
OPTIONAL 24V
FIELD WIRING (SEE NOTE)
17
DIAGRAM 2 – TWO STAGE FURNACE AND TWO STAGE AC

18
FAN
RELAY
2ND
STAGE
HEAT
1ST
STAGE
HEAT
R
ROOF TOP UNIT
C
G
W1
W2
Y2
Y1
L1
L2
120
VAC
24
VAC
IMPORTANT!
The B terminal is for
reversing valve-heat.
DO NOT connect the
B terminal to common
side of transformer.
1ST
STG
COOL
2ND
STG
COOL
G
Y1
W1
Y2
W2
RH
RC
O
APRILAIRE MODEL
8870 THERMOSTAT
COMMUNICATION
TERMINALS
B
C
RSB
RSR
RSC
R
RSA
B+
A-
A+
B-
REF
REMOTE
SENSOR(S)
NOTE: HVAC installer may need to connect
24V AC to the R and C terminals to check
the HVAC operation. If the automation
system is to be installed after the HVAC
installation, leave the R and C terminals
connected to ensure the HVAC system
operates. If the automation system is
installed before the HVAC wiring, then
DO NOT connect HVAC wires to R and C.
SEE
NOTE
24V FIELD WIRING
FACTORY WIRING
OPTIONAL 24V
FIELD WIRING (SEE NOTE)
DIAGRAM 3 – ROOF TOP UNIT (TWO STAGE HEAT AND TWO STAGE COOL)