A.O. Smith 650A, 740A warranty GAS Meter Size City Gases only, GAS Pressure Regulation, GAS Valves

TABLE 9A

MAXIMUM CAPACITY OF PIPE IN CUBIC FEET OF GAS PER HOUR

(Based upon a Pressure Drop of 0.5 inch Water Column and 0.5 Specific Gravity Gas and max. gas press. of .5 psig)

LENGTH
IN			Nominal Iron Pipe Sizes, Millimeters
METERS	1/2"	3/4"	1"	1 1/4"	1 1/2"	2"	2 1/2"	3"	4"
3.0	51	105	199	410	615	1160	1845	3221	6735
6.1	35	73	142	278	428	805	1277	2255	4626
9.1	28	59	110	225	346	644	1031	1830	3748
12.2	24	50	94	193	290	556	878	1552	3192
15.2	21	44	83	170	264	492	776	1391	2840
18.3	19	40	76	155	237	445	703	1259	2577
21.3	18	37	70	143	220	410	659	1142	2372
24.4	17	35	64	135	202	381	600	1083	2196
27.4	16	32	60	126	190	357	571	1010	2108
30.5	15	30	57	117	182	337	542	952	1962
38.1	13	27	51	105	161	299	483	864	1757
45.7	12	25	47	95	146	278	439	776	1610
53.3	11	23	42	88	135	249	401	717	1464
61.0	10	21	40	82	126	234	375	688	1347

WARNING

THE HEATER IS NOT INTENDED FOR OPERATION AT HIGHER THAN 14” (3.5 kPa) WATER COLUMN (1/2 POUND PER SQUARE INCH) SUPPLY GAS PRESSURE. HIGHER GAS PRESSURES REQUIRE SUPPLEMENTAL REDUCING SERVICE REGULATION. EXPOSURE TO HIGHER GAS SUPPLY PRESSURE MAY CAUSE DAMAGE TO THE GAS CONTROLS WHICH COULD RESULT IN FIRE OR EXPLOSION. IF OVERPRESSURE HAS OCCURRED SUCH AS THROUGH IMPROPER TESTING OF GAS LINES OR EMERGENCYMALFUNCTIONOFTHESUPPLYSYSTEM,THEGAS 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.

ANY SUPPLY PRESSURE TESTING EXCEEDING 1/2 PSIG. GAS

SUPPLY LINE MUST BE CAPPED WHEN DISCONNECTED FROM THE HEATER. FOR TEST PRESSURES OF ½ PSIG OR LESS, THE APPLIANCE NEED NOT BE DISCONNECTED, BUT MUST BE ISOLATED FROM THE SUPPLY PRESSURE TEST BY CLOSING THE MANUAL GAS SHUT-OFF VALVE.

GAS PIPING AND DIRT LEG INSTALLATION

FIGURE 9.

BEFOREPLACINGTHEHEATERINOPERATION,CHECKFORGAS LEAKAGE. USE SOAP AND WATER SOLUTION OR OTHER

MATERIAL ACCEPTABLE FOR THE PURPOSE IN LOCATING

GAS LEAKS. DO NOT USE MATCHES, CANDLES, FLAME OR

OTHER SOURCES OF IGNITION FOR THIS PURPOSE.

GAS METER SIZE – CITY GASES ONLY

Be sure that 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 the gas meter is too small, request the gas company to install a larger meter having adequate capacity.

GAS PRESSURE REGULATION

TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS SUPPLY LINE, A DIRT LEG (SOMETIMES CALLED A SEDIMENT TRAP OR DRIP LEG) MUST BE INCORPORATED IN THE PIPING (SEE FIG.

10)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 NATIONAL FUEL GAS CODE.

To prevent damage, care must be taken not to apply too much torque when attaching gas supply to gas valve inlet.

Apply joint compounds (pipe dope) sparingly and only to the male threads of pipe joints. Do not apply compound to the first two threads. Use compounds resistant to the action of liquefied petroleum gases.

DISCONNECT THE APPLIANCE AND ITS MANUAL GAS SHUT- OFF VALVE FROM THE GAS SUPPLY PIPING SYSTEM DURING

Main line gas pressure to the water heater should be between 8” w.c. (2 kPa) minimum (dynamic pressure or net pressure) and 14” (3.5 kPa) maximum w.c. (static pressure). The inlet gas pressure must not exceed the maximum value. A service regulator is necessary if higher gas pressures are encountered, see Table 10.

Due to pressure drop along gas supply line, to maintain 8” w.c. (2 kPa) minimum dynamic pressure, initial gas inlet pressure must be set at higher than 8” w.c. (2 kPa). The gas regulator must be properly sized to prevent unstable control or excessive pressure drop.

GAS VALVES

Figure 10 shows the gas control valve that is supplied on these heaters.

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