Goodman Mfg GAS-FIRED WARM AIR FURNACE installation instructions Rack, manifold or gas valve

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

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 semi-rigid 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.

0.60 Specific Gravity Gas)

CFH = BTUH Furnace Input

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 piping. Refer to Gas Piping Connections figure 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 GASES. DO NOT apply compound to the first two

GAS VALVE	BURNERS
MANIFOLD	ALTERNATE
PIPE	UNION
	LOCATION
UNION
GAS LINE
GROMMET IN
GAS LINE
HOLE

MANUAL

SHUT OFF VALVE (UPSTREAM FROM

PIPE UNION)

HEIGHT REQUIRED

BY LOCAL CODE

GROMMET

IN STANDARD

GAS LINE HOLE

DRIP LEG

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 three

inches 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.

• 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,

	GROMMET IN
	ALTERNATE
	GAS LINE
	HOLE
DRIP LEG	GAS VALVE
	BURNERS

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