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Size the main gas line in accordance with Table I. The figures
shown are for straight lengths of pipe at 0.5 in. W.C. pressure drop,
which is considered normal for low pressure systems. Note:
Fittings such as elbows, tees and line regulators will add to the
pipe pressure drop. Also refer to the latest version of the National
Fuel Gas Code.
TABLE 1 - GAS SUPPLY LINE SIZES (IN INCHES)*
MAXIMUM CAPACITY OF PIPE IN
CUBIC FEET PER HOUR
LENGTH
IN
FEET 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 4"
10 175 360 680 1400 2100 3960 6300 11000 23000
20 120 250 485 950 1460 2750 4360 7700 15800
30 97 200 375 770 1180 2200 3520 6250 12800
40 82 170 320 660 990 1900 3000 5300 10900
50 73 151 285 580 900 1680 2650 4750 9700
60 66 138 260 530 810 1520 2400 4300 8800
70 61 125 240 490 750 1400 2250 3900 8100
80 57 118 220 460 690 1300 2050 3700 7500
90 53 110 205 430 650 1220 1950 3450 7200
100 50 103 195 400 620 1150 1850 3250 6700
125 44 93 175 360 550 1020 1650 2950 6000
150 40 84 160 325 500 950 1500 2650 5500
175 37 77 145 300 460 850 1370 2450 5000
200 35 72 135 280 430 800 1280 2280 4600
LENGTH
IN
METERS 1/2" 3/4" 1" 1 1/4" 1 1/2" 2" 2 1/2" 3" 4"
3 51 105 199 410 615 1160 1845 3221 6735
6 35 73 142 278 428 805 1277 2255 4626
9 28 59 110 225 346 644 1031 1830 3748
12 24 50 94 193 290 556 878 1552 3192
15 21 44 83 170 264 492 776 1391 2840
18 19 40 76 155 237 445 703 1259 2577
21 18 37 70 143 220 410 659 1142 2372
24 17 35 64 135 202 381 600 1083 2196
27 16 32 60 126 190 357 571 1010 2108
31 15 30 57 117 182 337 542 952 1962
38 13 27 51 105 161 299 483 864 1757
46 12 25 47 95 146 278 439 776 1610
53 11 23 42 88 135 249 401 717 1464
61 10 21 40 82 126 234 375 688 1347
WARNING
THE HEATER IS NOT INTENDED FOR OPERATION AT HIGHER
THAN 14.0" W.C.(3.48 kPa) - NATURAL GAS, 14.0" W.C. (3.48 kPa)
- PROPANE GAS (1/2 POUND PER SQUARE INCH GAGE- 3.45
kPa) SUPPLY GAS PRESSURE. EXPOSURE TO HIGHER SUPPLY
PRESSURE MAY CAUSE DAMAGE TO THE GAS VALVE WHICH
COULD RESULT IN FIRE OR EXPLOSION. IF OVERPRESSURE
HAS OCCURRED SUCH AS THROUGH IMPROPER TESTING OF
GAS LINES OR EMERGENCY MALFUNCTION OF THE SUPPLY
SYSTEM, THE GAS VALVE MUST BE CHECKED FOR SAFE
OPERATION. MAKE SURE THAT THE OUTSIDE VENTS ON THE
SUPPLY REGULATORS AND THE SAFETY VENT VALVES ARE
PROTECTED AGAINST BLOCKAGE. THESE ARE PARTS OF THE
GAS SUPPLY SYSTEM, NOT THE HEATER. VENT BLOCKAGE
MAY OCCUR DURING ICE STORMS.
IT IS IMPORTANT TO GUARD AGAINST GAS VALVE FOULING FROM
CONTAMINANTS IN THE GAS WAYS. SUCH FOULING MAY CAUSE
IMPROPER OPERATION, FIRE OR EXPLOSION.
IF COPPER SUPPLY LINES ARE USED THEY MUST BE
INTERNALLY TINNED AND CERTIFIED FOR GAS SERVICE.
BEFORE ATTACHING THE GAS LINE, BE SURE THAT ALL GAS
PIPE IS CLEAN ON THE INSIDE.
TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS SUPPLY
LINE, A DIRT LEG (SOMETIMES CALLED SEDIMENT TRAP OR
DRIP LEG) MUST BE INCORPORATED IN THE PIPING (SEE
FIGURE 5). THE DIRT LEG MUST BE READILY ACCESSIBLE
AND NOT SUBJECT TO FREEZING CONDITIONS. INSTALL IN
ACCORDANCE WITH RECOMMENDATIONS OF SERVING GAS
SUPPLIERS. REFER TO THE LATEST VERSION OF THE
NATIONAL
FUEL GAS CODE.
GAS PIPING AND DIRT LEG INSTALLATION
FIGURE 5.
To prevent damage, care must be taken not to apply too much
torque when attaching gas supply pipe to gas valve inlet.
Apply joint compounds (pipe dope) sparingly and only to the male
threads of pipe joints. Do not apply compounds to the first two
threads. Use compounds resistant to the action of liquefied
petroleum gases.
BEFORE PLACING THE HEATER IN OPERATION, CHECK FOR
GAS LEAKAGE.
Use soap and water solution or other material
acceptable for the purpose in locating the leaks.
DO NOT USE
MATCHES, CANDLES, FLAME OR OTHER SOURCES OF IGNITION
FOR THIS PURPOSE.
DISCONNECT THE HEATER AND ITS MANUAL GAS SHUTOFF
VALVE FROM THE GAS SUPPLY PIPING SYSTEM DURING ANY
SUPPLY PRESSURE TESTING EXCEEDING 1/2 PSIG (3.45 kPa).
GAS SUPPLY LINE MUST BE CAPPED WHEN DISCONNECTED
FROM THE HEATER FOR TEST PRESSURES OF 1/2 PSIG (3.45
Kpa) OR LESS. THE APPLIANCE NEED NOT BE DISCONNECTED,
BUT MUST BE ISOLATED FROM THE SUPPLY PRESSURE TEST
BY CLOSING THE MANUAL GAS SHUTOFF VALVE.
GAS METER SIZE — NATURAL GASES ONLY
Be sure the gas meter has sufficient capacity to supply the full
rated gas input of the water heater as well as the requirements of
all other gas fired equipment supplied by the meter. If gas meter is
too small, ask the gas company to install a larger meter having
adequate capacity.
NORMAL IRON PIPE SIZES (INCHES)
INPUT IN THOUSANDS BTU/HR
NORMAL IRON PIPE SIZES (INCHES)
INPUT IN KW