107272-UIM-B-1105

TABLE 16: Gas Line Piping Size and Length

Length of Pipe in

 

Nominal Diameter of Pipe in Inches (mm)

 

 

 

 

 

 

3/4 (19.05)

1 (25.4)

1-1/4 (31.75)

1-1/2 (38.1)

2 (50.8)

Feet (Meter)

Capacity-Cu. Ft. (m3) Per Hr. with a 0.6 Sp. Gr. Gas and Pressure Drop of 0.3 in. (74.72 Pa) Water Col.

 

15 (4.572)

172 (4.87)

345 (9.77)

750 (21.24

30 (9.144)

120 (3.4)

241 (6.82)

535 (15.15)

850 (24.07)

45 (13.72)

99 (2.8)

199 (5.64)

435 (12.32)

700 (19.82)

60 (18.29)

86 (2.44)

173 (4.90)

380 (10.76)

610 (17.27)

75 (22.86)

77 (2.18)

155 (4.34)

345 (9.77)

545 (15.43)

105 (32)

65 (1.84)

131 (3.71)

285 (8.07)

450 (12.74)

920 (26.05)

120 (36.58)

120 (3.4)

270 (7.65)

420 (11.89)

860 (24.35)

180 (54.86)

100 (2.83)

225 (6.37)

350 (10.76)

720 (20.39)

The building structure should not be weak end by installation for the gas piping. The piping should not be supported by the other piping, but should be firmly supported with pipe hooks, straps, bands, or hanger. Butt or lap welded pipe should not be bent.

The gas piping should be so installed so as to prevent an accumulation of condensation and it must be protected against freezing. A horizontal pipe should be pitched so that it grades toward the meter and is free from sags. The pipe can not be run through or in an air duct or clothes chute.

The appliance and its individual shut-off valve must be disconnected from the gas supply piping system during any pressure testing of the system at test pressure in excess of 1/2 (3447 PaG) psig.

The appliance must be isolated from the gas supply piping system by closing its individual manual shut-off valve during any pressure testing of the gas supply piping system at test pressures equal to or less than 1/2 (3447 PaG) psig. Refer to Figure 40.

Some utility companies or local codes require pipe sizes larger than the minimum sizes listed in these instructions and in the codes. The furnace rating plate and the instructions in this section specify the type of gas approved for this furnace - only use those approved gases.

IMPORTANT: An accessible manual shut-off valve must be installed upstream of the furnace gas valve and within 6 feet (1.8 m) of the fur- nace.

TESTING PIPING FOR LEAKS

Before turning on gas under pressure into piping, all openings from which gas can escape should be closed. Immediately after turning on gas, the system should be checked for leaks. This can be done by watching the 1/2 cubic feet (0.14 m3) test dial and allowing 5 minutes to show any movement, or by soaping each pipe connection and watching for bubbles. If a leak is found, make the necessary repairs and repeat the above test.

DEFFECTIVE PIPES OR FITTINGS SHOULD BE REPLACED AND NOT REPAIRED. NEVER USE A FLAME OR FIRE IN ANY FORM TO

Gas Piping

From Meter

Gas Line

Shutoff

Valve

Direction

of Flow

Black

Iron Pipe

3.00 Min.

Tee

(72.6)

 

Drip

Leg

Pipe Cap

Manual Shutoff Valve

(Close this valve during pressure testing of the gas line)

1/8” NPT Plugged

Tapping Pressure

Gauge Port

Union

To Gas

Valve

Control

Manifold

Floor Level

LOCATE GAS LEAKS, USE A SOAP SOLUTION.

TABLE 17: Length of Standard Pipe Threads in Inches (mm)

PIPE SIZE

EFFECTIVE LENGTH

OVERALL LENGTH

OF THREAD

OF THREAD

 

 

 

 

 

3/8 (9.53)

3/8

(9.53)

9/16 (14.29)

1/2 (12.7)

1/2

(12.7)

3/4 (19.05)

3/4 (19.05)

1/2 - 9/16 (14.29)

13/16 (20.64)

1 (25.4)

9/16

(14.29)

1 (25.4)

2Imprerfect Threads

Leave 2 End

Threads Bare

LOCATION OF UNION AND DRIP LEG FOR

CONNECTING BURNER TO HOUSING PIPING

FIGURE 40: Manual Shut-off Valve/Gas Piping

GAS PIPING INSTALLATION

Properly sized wrought iron, approved flexible or steel pipe must be used when making gas connections to the unit. If local codes allow the use of a flexible gas appliance connection, always use a new listed con- nector. Do not use a connector that has previously serviced another gas appliance.

FIGURE 41: Proper Piping Practice

If the gas input to the furnace is too great because of excessive gas pressure, wrong size orifice, high altitude, etc., the burner flame will be sooty and may produce carbon monoxide, which could result in unsafe operation, explosion, and/or fire or asphyxiation.

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Unitary Products Group

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York DFAH, DFAA Testing Piping for Leaks, GAS Piping Installation, Length of Pipe Nominal Diameter of Pipe in Inches mm