Installations Instructions
32
CAUTION
T
O
PREVENT
UNRELIABLE
OPERATION
OR
EQUIPM ENT
DAM AGE
,
THE
INLET
GAS
SUPPLY
PRESSURE
M UST
BE
AS
SPECIFIED
ON
THE
UNIT
RATING
PLATE
W ITH
ALL
OTHER
HOUSEHOLD
GAS
FIRED
APPLIANCES
OPERATING
.
Inlet gas supply pressures must be maintained within the ranges
specified in the following table. The supply pressure must be
constant and available with all other household gas fired appli-
ances operating. The minimum gas supply pressure must be
maintained to prevent unreliable ignition. The maximum must
not be exceeded to prevent unit overfiring.
Natural Gas Minimum: 4.5" w.c. Maximum: 10.0" w.c.
Propane Gas Minimum: 11.0" w.c. Maximum: 13.0" w.c.
Inlet Gas Supply Pressure
A heat pump thermostat with t hree st ages 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) installa-
tion instructions for additional thermostat requirements.
HIGH ALTITUDE DERATE
In some areas the gas supplier may artificially derate the gas
in an effort to compensate for the effects of altitude. If the
gas is artificially derated, the appropriate orifice size must be
determined based upon the BTU/ft
3
content of the derated gas
and the altitude. Refer to the National Fuel Gas Code, NFPA 54/
ANSI Z223.1 or CAN/CSA B149.1-15 in Canada, and informa-
tion provided by the gas supplier to determine the proper orifice
size.
PROPANE GAS CONVERSION
WARNING
P
OSSIBLE
PROPERTY
DAM AGE
,
PERSONAL
INJURY
OR
DEATH
M AY
OCCUR
IF
THE
CORRECT
CONVERSION
KITS
ARE
NOT
INSTALLED
. T
HE
APPROPRIATE
KITS
M UST
BE
APPLIED
TO
ENSURE
SAFE
AND
PROPER
FURNACE
OPERATION
. A
LL
CONVERSIONS
M UST
BE
PERFORM ED
BY
A
QUALIFIED
INSTALLER
OR
SERVICE
AGENCY
.
As shipped, this unit is configured for natural gas. The LPM-09
is required to convert this furnace to operate on LP gas.
The correct kit must be used to insure safe and proper furnace
operation. All conversions must be performed by a qualified
installer, or service agency.
GAS VALVE
This unit is equipped with a 24 volt gas valve which modulates
by pneumatic linkage to the combustion air blower. Taps for
measuring the gas supply pressure and manifold pressure are
provided on the valve. This is a non-convertible, non-adjust-
able gas valve equipped for natural gas.
The gas valve has a manual ON/OFF control located on the valve
itself. This control may be set only to the “ON” or “OFF” posi-
tion. Refer to the lighting instructions label or the St art up Pr oce-
dure & Adj ust ment section of this manual for use of this con-
trol during start up and shut down periods.
GAS PIPING CONNECTIONS
T
O
AVOID
POSSIBLE
UNSATISFACTORY
OPERATION
OF
EQUIPM ENT
DAM AGE
DUE
TO
UNDERFIRING
OR
EQUIPM ENT
,
USE
THE
PROPER
SIZE
OF
NATURAL
/
PROPANE
GAS
PIPING
NEEDED
W HEN
RUNNING
PIPE
FROM
THE
M ETER
/
TANK
TO
THE
FURNACE
.
WARNING
The gas piping supplying the furnace must be properly sized based
on the gas flow required, specific gravity of the gas, and length
of the run. The gas line installation must comply with local codes,
or in their absence, with the latest edition of the National Fuel
Gas Code, NFPA 54/ANSI Z223.1 or CAN/CSA B149.1-15 in
Canada.
Natural Gas Capacity of Pipe In Cubic Feet of Gas Per Hour (CFH)
Nominal
½¾11¼1½22½
Actual ID:
0.622 0.824 1.049 1.380 1.610 2.067 2.469
Length (ft)
10 170 360 678 1390 2090 4020 6400
20 118 247 466 957 1430 2760 4400
30 95 199 374 768 1150 2220 3530
40 81 170 320 657 985 1900 3020
50 72 151 284 583 873 1680 2680
60 65 137 257 528 791 1520 2430
70 60 126 237 486 728 1400 2230
80 56 117 220 452 677 1300 2080
90 52 110 207 424 635 1220 1950
100 50 104 195 400 600 1160 1840
125 44 92 173 355 532 1020 1630
150 40 83 157 322 482 928 1480
175 37 77 144 296 443 854 1360
200 34 71 134 275 412 794 1270
250 30 63 119 244 366 704 1120
Capacity in Cubic Feet of Gas per Hour
This chart ref ers to natural gas w ith an inlet pressure of less than 2 psi and a
pressure drop of 0.5" W.C. Specif ic gravity is 0.60.
Pipe Size (in.)
CFH = BTUH Furnace Input
Heating Valve of Gas (BTU/Cubic Foot)
To connect the furnace to the building’s gas piping, the installer
must supply a ground joint union, drip leg, manual shutoff valve,
and line and fittings to connect to gas valve. In some cases, the
installer may also need to supply a transition piece from 1/2"
pipe to a larger pipe size.