Installation Guide
31
FOSSIL FUEL APPLICATIONS
This furnace can be used in conjunction with a heat pump in a
fossil fuel application. A fossil fuel application refers to a com-
bined gas furnace and heat pump installation which uses an out-
door temperature sensor to determine the most cost efficient means
of heating (heat pump or gas furnace).
A heat pump thermostat with three stages of heat is required to
properly use a two-stage furnace in conjunction with a heat pump. Refer to the fossil fuel kit (AFE18-60A) installation instructions
for additional thermostat requirements.
Strictly follow the wiring guidelines in the fossil fuel kit installation instructions. All furnace connections must be made to the furnace
control board and the “FURNACE” terminal strip on the fossil fuel
control board.
LINE VOLTAGE ACCESSORIES (ELECTRONIC AIR CLEANER AND
HUMIDIFIER)
The furnace control board is equipped with line voltage accessory
terminals for controlling power to an electronic air cleaner.
The accessory load specifications are as follows. (The furnace
control board also has a set of dry contacts for humidifier con-
nection.)
Turn OFF power to the furnace before installing any accessories.
Follow the humidifier or air cleaner manufacturers’ instructions for
locating, mounting, grounding, and controlling these accessories.
Accessory wiring connections are to be made through the 1/4" quick connect terminals provided on the furnace integrated control
module. The Electronic air cleaner hot terminal is identified as EAC. It is necessary to remove the protective tab on the board
cover to access the EAC Terminal. The EAC neutral terminal is identified as NEU-
TRAL. A line voltage humidifier may be connected between one of the HUM con-
tacts and NEUTRAL. The other HUM contact must be fed from the L1 terminal.
All field wiring must conform to applicable codes. Connections should be made as shown
in Figure 34.
If it is necessary for the installer to supply additional line voltage wiring to the inside of
the furnace, the wiring must conform to all local codes, and have a minimum tempera-
ture rating of 105°C. All line voltage wire splices must be made inside the furnace
junction box.
The furnace control board HUM (dry contacts) are closed whenever the inducer is
energized in a non-communicating installation. When used with a CTK02**, CTK03
or CTK04 communicating thermostat, the HUM terminals are closed whenever there
is a call for humidity. The integrated control module electronic air cleaner terminals
(EAC) are energized with 115 volts whenever the circulator blower is energized.
24 VOLT HUMIDIFIER
A 24 volt humidifier can be powered by feeding one of the HUM
terminals with a field installed wire from the R terminal.
G
AS
S
UPPLY
AND
P
IPING
The furnace rating plate includes the approved furnace gas input
rating and gas types. The furnace must be equipped to operate on
the type of gas applied. This includes any conversion kits required
for alternate fuels and/or high altitude.
HIGH VOLTAGE !
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
DISCONNECT
ELECTRICAL
POWER
BEFORE
SERVICING
OR
CHANGING
ANY
ELECTRICAL
WIRING
.
WARNING
HIGH VOLTAGE !
T
O
AVOID
PERSONAL
INJURY
OR
DEATH
DUE
TO
ELECTRICAL
SHOCK
,
DISCONNECT
ELECTRICAL
POWER
BEFORE
SERVICING
OR
CHANGING
ANY
ELECTRICAL
WIRING
.
WARNING
Humidifier 1.0 Amp maximum at 120 VAC
Electronic Air Cleaner 1.0 Amp maximum at 120 VAC
AUX OUT
AUX IN
L1
NEUTRAL
Accessories Wiring
Figure 34
CAUTION
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPMENT
DAMAGE
,
THE
INLET
GAS
SUPPLY
PRESSURE
MUST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
WITH
ALL
OTHER
HOUSEHOLD
GAS
FIRED
APPLIANCES
OPERATING
.