29
ELECTRICAL CONNECTIONS
- +
Custom defrost
mode jumper
selection
3 position mode
selection switch
Accessory Control Contact
(Open & Closes contact when HRV/ERV is ON/OFF)
Diagnostic
LED
U
15-minute timer
(up to 5 timers)
EDF5 or EDF2
(not shown)
Dehumidistat
2 wires
Dehumidistat
On/Off
4 wires
Mechanical
Crank Timer
2 wires
and /
or
and /
or
(1 only)
Air Quality
Sensor
2 wires
2 wires
3 wires
W
R
G
C
Y
W
R
G
Y
Standard Furnace Interlock Wiring
THERMOSTAT
TERMINALS
FURNACE
24-VOLT
TERMINAL BLOCK
FOUR
WIRE
TWO WIRE
heating only
TWO
WIRE
COOLING SYSTEM
HRV
ELECTRONIC BOARD
W
R
G
C
Y
W
R
G
Y
Alternate Furnace Interlock Wiring
THERMOSTAT
TERMINALS
FURNACE
24-VOLT
TERMINAL BLOCK
FOUR
WIRE
TWO WIRE
heating only
TWO
WIRE
COOLING SYSTEM
HRV
ELECTRONIC BOARD
WIRE JOINT
Caution:
• Never connect a 120 volt AC
circuit to the terminals of the
Accessory Control Contacts.
Only use the low voltage
class 2 circuit of the furnace
blower control.
For a Furnace Connected to a
Cooling System:
• On some older thermostats,
energizing the R and G
terminals at the furnace has
the effect of energizing Y at
the thermostat and thereby
turning on the cooling
system. If you identify this
type of thermostat, you must
use the “Alternate Furnace
Interlock Wiring”.
PRACTICAL TIPS
ELECTRICAL CONNEC-
TION TO A FURNACE
Standard Accessory Control Contact
Alternate Accessory Control Contact
* Wiring diagram of complete unit
inside of access panel
Found on
electrical
box