Goodman ACS series Service Instructions Manual page 57

PRODUCT DESIGN
When sizing a trunk line, be sure to include all appliances
which will operate simultaneously when sizing a trunk line.
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.
Natural Gas Capacity of Pipe
In Cubic Feet of Gas Per Hour (CFH)
Length of
Pipe in Feet 1/2"
10 132
20 92
30 73
40 63
50 56
60 50
70 46
80 43
90 40
100 38
(Pressure 0.5 psig or less and pressure drop of 0.3" W.C.; Based on 0.60 Specific
Gravity Gas)
BTUH Furnace Input
CFH =
Heating Value 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.
The following stipulations apply when connecting gas pip-
ing. Refer to the following figures for typical gas line con-
nections to the furnace.
1. Use black iron or steel pipe and fittings for the build-
ing piping.
2. Use pipe joint compound on male threads only. Pipe
joint compound must be resistant to the action of the
fuel used.
3. Use ground joint unions.
4. Install a drip leg to trap dirt and moisture before it can
enter the gas valve. The drip leg must be a minimum
of three inches long.
5. Install a 1/8" NPT pipe plug fitting, accessible for test
gage connection, immediately upstream of the gas
supply connection to the furnace.
6. Use two pipe wrenches when making 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.
7. Install a manual shutoff valve between the gas meter
and unit within six feet of the unit. If a union is in-
stalled, the union must be downstream of the manual
shutoff valve, between the shutoff valve and the fur-
nace.
8. Tighten all joints securely.
Nominal Black Pipe Size
3/4" 1" 1 1/4"
278 520 1050
190 350 730
152 285 590
130 245 500
115 215 440
105 195 400
96 180 370
90 170 350
84 160 320
79 150 305
9. 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. Alu
minum 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.
10. Use listed gas appliance connectors in accordance with
1 1/2"
their instructions. Connectors must be fully in the same
1600
room as the furnace.
1100
980
11. Protect connectors and semi-rigid tubing against physi-
760
cal and thermal damage when installed. Ensure alumi-
670
num-alloy tubing and connectors are coated to protect
610
560 against external corrosion when in contact with masonry,
530
plaster, or insulation, or subjected to repeated wetting
490
by liquids such as water (except rain water), detergents,
460
or sewage.
E
DGES OF SHEET METAL HOLES MAY BE SHARP.
WHEN REMOVING HOLE PLUGS.
DIRECT/STANDARD INLET PIPING
When gas piping enters directly to the gas valve through the
standard inlet hole (upflow through the right side panel), the
installer must supply straight pipe with a ground joint union
to reach the exterior of the furnace. NOTE: The rigid pipe
must be long enough to reach the outside of the cabinet to
seal the grommet cabinet penetration on 90% furnaces. A
semi-rigid connector to the gas piping can be used outside
the cabinet per local codes.
INDIRECT/ALTERNATE INLET PIPING
When gas piping enters indirectly to the gas valve through
the alternate gas inlet hole the installer must supply the
following fittings (starting from the gas valve) to reach the
outside of the cabinet (NOTE: On the 90% furnaces the in-
staller must swap the alternate inlet hole plug with the stan-
dard inlet grommet in order to seal the cabinet):
• Coupling.
• 90 degree elbow.
• 2 inch close nipple.
• 90 degree elbow.
• Straight pipe, with a ground joint union, to reach the
exterior of the furnace. NOTE: The rigid pipe must be
long enough to reach the outside of the cabinet so as
to seal the grommet cabinet penetration on the 90%
furnaces. A semi-rigid connector to the gas piping can
be used outside the cabinet per local codes.
CAUTION
U
SE GLOVES A PRECAUTION
57