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)
FAN
RELAY
1ST
STAGE
HEAT
R
ONE STAGE FURNACE
C
G
W1
Y1
1ST STAGE
COOL
L1
L2
120
VAC
24
VAC
1ST
STG
COOL
COOLING EQUIPMENT
Y1
C
Aprilaire Model 8024
24-volt Relay Pack
(not supplied)1
2
3
4
5
6
7
8
9
W
R
Y
24V
COM
E/W2
Y
O
SEE
NOTE
IMPORTANT!The thermostat 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.24V FIELD WIRINGFACTORY WIRINGOPTIONAL 24VFIELD WIRING (SEE NOTE)1ST
STAGE
HEAT
R
RADIANT FLOOR HEAT
C
W
L1
L2
120
VAC
24
VAC