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) | 2 (50.8) | ||||
Feet (Meter) | ||||||
| ||||||
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
The appliance must be isolated from the gas supply piping system by closing its individual manual
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
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.
30 | Unitary Products Group |