22
itself. This control may be set only to the “ON” or “OFF” position.
Refer to the lighting instructions label or
Startup Procedure &
Adjustment
for use of this control during start up and shut
down periods.
Gas Piping Connections
T
O
AVOID
THE
POSSIBILITY
OF
EXPLOSION
OR
FIRE
,
NEVER
USE
A
MATCH
OR
OPEN
FLAME
TO
TEST
FOR
LEAKS
.
WARNING
I
F
THE
GAS
FURNACE
IS
INSTALLED
IN
A
BASEMENT
,
AN
EXCAVATED
AREA
OR
CONFINED
SPACE
,
IT
IS
STRONGLY
RECOMMENDED
TO
CONTACT
A
CERTIFIED
CONTRACTOR
TO
INSTALL
A
GAS
DETECTING
WARNING
DEVICE
IN
CASE
OF
A
GAS
LEAK
.
WARNING
When sizing gas lines, be sure to include all appliances
which will operate simultaneously. 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
To connect the furnace to the building’s gas piping, the install
-
er 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.
The following stipulations apply when connecting gas piping.
Refer to
Gas Piping Connections
figures 29 and 30 for typical
gas line connections to the furnace.
• Gas piping must be supported external to the furnace
cabinet so that the weight of the gas line does not
distort the burner rack, manifold or gas valve.
•
Use black iron or steel pipe and fittings for building
piping. Where possible, use new pipe that is properly
chamfered, reamed, and free of burrs and chips. If old
pipe is used, be sure it is clean and free of rust, scale,
burrs, chips, and old pipe joint compound.
•
Use pipe joint compound on male threads ONLY.
Always use pipe joint compound (pipe dope) that is
APPROVED FOR ALL GASSES. DO NOT apply
compound to the first two threads.
•
Use ground joint unions.
•
Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum
of 3” long.
•
Install a 1/8” NPT pipe plug fitting, accessible for test
gauge connection, immediately upstream of the gas
supply connection to the furnace.
•
Always use a back-up wrench when making the
connection to the gas valve to keep it from turning.
The orientation of the gas valve on the manifold must
be maintained as shipped from the factory. Maximum
torque for the gas valve connection is 375 in-lbs;
excessive over-tightening may damage the gas valve.
•
Install a manual shutoff valve between the gas meter
and unit within six feet of the unit. If a union is installed,
the union must be downstream of the manual shutoff
valve, between the shutoff valve and the furnace.
•
Tighten all joints securely.
•
Connection method must be in compliance with all
local and national codes. US: National Fuel Gas
Code (NFGC) NFPA 54-2012/ANSI Z223.1-2012 and
the Installation Standards, Warm Air Heating and Air
Conditioning Systems ANSI/NFPA 90B.
Connect the furnace to the building piping by one of
the following methods:
–
Rigid metallic pipe and fittings.
–
Semi-rigid metallic tubing and metallic fittings.
Aluminum alloy tubing must not be used in exterior
locations. In order to seal the grommet cabinet
penetration, rigid pipe must be used to reach the
outside of the cabinet. A semi-rigid connector to
the gas piping may be used from there.
•
Use listed gas appliance connectors in accordance
with their instructions. Connectors must be fully in
the same room as the furnace.
•
Protect connectors and semirigid tubing against
physical and thermal damage when installed. Ensure
aluminum-alloy tubing and connectors are coated to
protect against external corrosion when in contact
with masonry, plaster, or insulation, or subjected to
repeated wetting by liquids such as water (except rain
water), detergents, or sewage.
Natural Gas Capacity of Pipe
In Cubic Feet of Gas Per Hour (CFH)
Length of
Nominal Black Pipe Size
Pipe in Feet
1/2"
3/4"
1"
1 1/4"
1 1/2"
10
132
278
520
1050
1600
20
92
190
350
730
1100
30
73
152
285
590
980
40
63
130
245
500
760
50
56
115
215
440
670
60
50
105
195
400
610
70
46
96
180
370
560
80
43
90
170
350
530
90
40
84
160
320
490
100
38
79
150
305
460
(Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; Based on
0.60 Specific Gravity Gas)
CFH = BTUH Furnace Input
Heating Value of Gas (BTU/Cubic Foot)
TABLE 6
The gas piping may enter the left or right side of the furnace
cabinet. The installer must supply rigid pipe long enough to
reach the outside of the cabinet to seal the grommet cabinet
penetration. A semi-rigid connector to the gas piping can be
used outside the cabinet per local codes. 1/2” NPT pipe and
fittings are required. For models with an “L” shaped mani
-
fold, a 4 1/2” long nipple is required. For models with a hook
shaped manifold, a 2” long nipple is required.
