NOTE:
DO NOT set high-heat manifold pressure less than 3.2-in. wc or more than 3.8-in. wc for natural gas. If manifold pressure is outside this
range, change main burner orifices.
CAUTION: DO NOT bottom out gas valve regulator adjusting screw. This can result in unregulated manifold pressure
and result in excess overfire and heat exchanger failures.
NOTE:
If orifice hole appears damaged or it is suspected to have been redrilled, check orifice hole with a numbered drill bit of correct size. Never
redrill an orifice. A burr-free and squarely aligned orifice hole is essential for proper flame characteristics.
e. Remove jumper across R and W2 thermostat connections to place furnace in low-heat stage operation.
f. Turn low-heat stage adjusting screw (5/64 hex Allen wrench) counterclockwise (out) to decrease input rate or clockwise (in) to increase
input rate.
NOTE:
DO NOT set low-heat manifold pressure less than 1.3-in. wc or more than 1.7-in. wc maximum for natural gas. If manifold pressure is
outside this range, change main burner orifices.
g. Remove jumper across R and W/W1 thermostat connections after low-heat stage adjustments.
h. Replace gas valve regulator adjustment screw caps.
i. Turn setup switch SW-2 (on control board) to OFF position. (See Fig. 6 and 7.)
Fig. 6—Non-Condensing Furnace Control Center
(2-Speed Control Shown)
A93348
1
2
3
4
5
6
7
8
9
PR2
L2
COM
PR1
L1
EAC-2
EAC-1
H
I-
COO
L
HI-GAS
-HEAT
LO-GAS
-HEAT
PARK
3
FU1
SEC-1
SEC-2
1
1
2
3
4
5
6
7
8
9
10
11
12
MASTER SLAVE
TWIN
TEST
LED
G
R
Y/Y2
W/W1
COM
24 V
W2
1
ON
OFF
1
2
3
4
FURNACE AND
BLOWER OFF DELAY
SETUP SWITCHES
24-VOLT
THERMOSTAT
TERMINALS
EAC - ELECTRONIC
AIR CLEANER
(115-VAC 1 AMP MAX)
3-AMP
FUSE
LED -
DIAGNOSTIC
LIGHT
TWIN / TEST
TERMINAL
HUM -
HUMIDIFIER
(24-VAC 0.5
AMP MAX)
HUM
Fig. 7—Setup Switches on Control Center
(Factory Settings Shown)
A96402
BLOWER-
OFF
DELAY
LOW
HEAT
(ADAPTIVE
ALGORITHM)
HIGH
HEAT
ONLY
4
3
2
OFF
ON
1
CAUTION: DO NOT redrill burner orifices. Improper drilling (burrs, out-of-round holes, etc.) can cause excessive
burner noise and misdirection of burner flames. This can result in flame impingement of the burners and heat exchangers
causing failure. Obtain new orifices if orifice size must be changed.
A96249
BURNER
ORIFICE
BURNER
ORIFICE
—13—
