Step 10—Start-Up, Adjustment, and Safety Check
GENERAL
The furnace must have a 115-v power supply properly connected
and grounded. Correct polarity must be maintained to enable gas
heating operation.
The gas service pressure must not exceed 0.5 psig (14-in. wc), and
be no less than 0.16 psig (4.5-in. wc).
Thermostat wire connections at R and W/W1 are the minimum
required for gas heating operation. W2 must be connected for
2-stage heating thermostats. Com, Y/Y2, and G are required for
cooling, heat pumps, and some clock thermostats. These must be
made at the 24-v terminal block on the control. (See Fig. 11.)
This furnace can be installed with either a single-stage heating or
a 2-stage heating thermostat.
For single-stage thermostats, connect thermostat W to W/W1 at the
furnace control terminal block. (See Fig. 12.) For single-stage
thermostats the control determines, based on length of previous
heating on and off cycles, when to operate in low- and high-gas
heat for optimum comfort. Setup Switch-2 (SW-2) must be in the
factory-shipped OFF position. See Fig. 14 and Tables 6 and 7 for
setup switch information.
If a 2-stage heating thermostat is to be used, move SW-2 to the ON
position at the end of the furnace installation. This overrides the
built-in control process for selecting high and low fire and allows
the 2-stage thermostat to select gas heating modes. The W2 from
the thermostat must be connected to W2 on the control terminal
block. (See Fig. 13.)
Before operating the furnace, check each manual reset switch for
continuity. If necessary, press and release the button to reset the
switch.
Table 5—Electrical Data
UNIT
SIZE
VOLTS—
HERTZ—
PHASE
OPERATING
VOLTAGE RANGE
MAX
UNIT
AMPS
MIN
WIRE
GAGE
MAX WIRE
LENGTH
FT‡
MAX FUSE OR
HACR-TYPE
CKT BKR AMPS†
Max*
Min*
065-08
115—60—1
127
104
8.0
14
46
15
065-12
115—60—1
127
104
11.0
14
33
15
085-12
115—60—1
127
104
12.0
14
30
15
085-16
115—60—1
127
104
13.2
14
28
15
105-20
115—60—1
127
104
17.2
12
33
20
125-20
115—60—1
127
104
18.4
12
31
20
* Permissible limits of the voltage range at which the unit will operate satisfactorily.
† Time-delay fuse is recommended.
‡ Length shown is as measured 1 way along wire path between unit and service panel for maximum 2 percent voltage drop.
Fig. 12—Heating and Cooling Application Wiring Diagram With 1-Stage Thermostat and Condensing Unit
A93378
115-VOLT FIELD-
SUPPLIED
FUSED
DISCONNECT
JUNCTION
BOX
CONTROL
BOX
24-VOLT
TERMINAL
BLOCK
TWO-WIRE
HEATING-
ONLY
FOUR
WIRE
1-STAGE
THERMOSTAT
TERMINALS
FIELD-SUPPLIED
FUSED DISCONNECT
CONDENSING
UNIT
FURNACE
COM
R
W
Y
R
G
GND
GND
FIELD 24-VOLT WIRING
FIELD 115-, 208/230-, 460-VOLT WIRING
FACTORY 24-VOLT WIRING
FACTORY 115-VOLT WIRING
NOTE: Connect Y-terminal as
shown for proper
operation.
NOTE: If any of the original wire,
as supplied, must be replaced, use
same type or equivalent wire.
208/230- OR
460-VOLT
THREE
PHASE
208/230-
VOLT
SINGLE
PHASE
WHT
BLK
WHT
BLK
W/W1
W2
Y/Y2
G
Table 6—Setup Switch Description
SETUP
SWITCH NO.
NORMAL
POSITION
DESCRIPTION OF USE
SW-1
Only High-Gas Heat
OFF
(Staged Gas
Heat)
Turn switch on to obtain only
high-gas-heat operation on
any call for heat regardless of
whether R-W/W1, or R-W/W1,
-W2 is closed. SW-1 overrides
SW-2.
SW-2
Low-Gas Heat
(Adaptive Mode)
OFF
(Single-Stage
Thermostat)
Turn switch off for installations
with single-stage thermostats;
control selects low-gas-heat
or high-gas-heat operation
based on previous cycles.
Turn switch on for installations
with 2-stage thermostats to
permit only low-gas-heat op-
eration in response to closing
R-W/W1. High-gas heat is
supplied only when R to
W/W1 and W2 is closed.
SW-3 and
SW4
ON, OFF
Switches control gas heating
blower off delay. (See Table
7.)
9