Honeywell PC8900A Manual page 7

IMPORTANT
Be sure to connect the C terminal to transformer
common.
IN NEW INSTALLATION:
1. Locate the terminal strip(s) on the HVAC equipment.
2. Refer to Fig. 11 through 20 for wiring diagrams for
specific equipment applications.
3. Connect all loads to the appropriate W8900A-C wiring
terminal using 18-gauge, color-coded thermostat wire;
see Fig. 10.
4. Use a small screwdriver to connect the loads. Do not
overtighten; device can be damaged.
W8900A, C Terminal Designation
1
2
3
4
B
C
CO
2
VNT
G
GND
HUM
OUT
O
R
RC
RH
S, S1
See note a
See note b
T, T1
W1
W1
W2
Y1
Y1
Y2
See note c
See note c
See note d
none
a PC8900A/W8900A,C are not compatible with evaporative cooling equipment.
b In single stage heat pump applications, jumper W1 and Y1 and connect to Y. Configure the system for Auto Fan in Heat.
c
Dual fuel fan feature configured in installer setup.
d
Filter light feature available in PC8900A fan accumulation timer feature.
Table 2. Conventional Applications (W8900A or C).
Function
PC8900A Control Panel
PC8900A Control Panel
PC8900A Control Panel
PC8900A Control Panel
Heating, changeover valve
24 Vac Transformer Common
Carbon Dioxide Monitor
VNT Relay
Fan Relay
Ground
Humidity Relay
Outdoor Air Temperature Sensor
Cooling, Changeover Valve
24 Vac System Transformer
24 Vac Cooling Transformer
24 Vac Heating Transformer
Remote Air Temperature Sensor
Fan Control—Evaporative Cooling
Heat Pump Contactor
Discharge Air Temperature Sensor
Heating Relay
Stage 1 Heat Relay
Stage 2 Heat Relay
Cooling Relay
Stage 1 Cool Relay
Stage 2 Cool Relay
Fan Control (Honeywell dual fuel thermostat [T834])
Fan Control (Honeywell dual fuel thermostat [T834])
Filter Light
Remote Timer Contacts
7
W8900
FOR STRAIGHT
CONNECTION—
STRIP 5/16 IN. (8 MM)
FOR WRAPAROUND
CONNECTION—
STRIP 7/16 IN. (11 MM)
M4464
Fig. 10. Proper wiring technique for
W8900A-C and PC8900A.
Existing Thermostat Designation
—
—
—
—
B
C
—
—
G
—
—
—
O
R
RC
RH
—
F
P
—
W
W1
W2
Y
Y1
Y2
1
2
X
Z
68-0173—3