American Water Heater GAS-FIRED COMMERCIAL WATER HEATER - Manual (Page 21)

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The gas supply lines must meet all requirements of the National Fuel Gas
Code (ANSI Z223.1-Latest Edition), or in Canada CAN/CGA B149.1 Natural
Gas Installation Code (Latest Edition) or CAN/CGA B149.2 Propane
Installation Code (Latest Edition).
The minimum permissible gas supply pressure for the purpose of input
adjustment is one (1.0) inch (0.25 kPa) water column above the operating
manifold pressure. See the rating plate and gas valve for the manifold
pressure and gas type. The maximum permissible gas supply pressure is
fourteen (14.0) inches (3.5 kPa) water column for natural gas and liquefied
petroleum gases/propane gas.
1. Connect this water heater only to the type of gas (Natural or Propane gas)
as shown on the rating plate. Use clean black iron pipe or equivalent
material approved by local codes and ordinances. (Dirt and scale from the
pipe can enter the gas valve and cause it to malfunction). The inlet gas
line must have a minimum length of three (4) inches (7.6 cm) drip leg
(sediment trap) installed as close to the water heater’s gas valve as
possible. A ground joint union must be installed in the gas supply line, as
close to the water heater as possible, feeding the water heater to permit
servicing of the water heater. Compounds used on the threaded joints of
the gas piping must be resistant to the action of liquefied petroleum
gases/propane gas. DO NOT apply pipe dope to the gas valve inlet and
make certain that no pipe dope has become lodged in the inlet screen of
the gas valve. Extreme care shall be taken to ensure no pipe dope enters
the gas valve and to avoid excessive torque when tightening the gas
supply line to the gas valve. Excessive torque may result in cracking of
the gas valve housing. The suggested maximum torque is 31.5 ft. lbs.
(4.4 kg-m). The manufacturer of this water heater will not be liable for any
damage or injury caused as a result of a cracked gas inlet as a result of
excessive torque.
2. This water heater and its gas connection must be leak tested before
placing the water heater in operation. Check for gas leaks with a soap
and water solution and a brush or a commercial leak detector fluid.
NEVER USE A MATCH OR OPEN FLAME FOR TESTING!
GENERAL OPERATION
CAUTION
The water heater and individual shutoff valve must be disconnected from
the gas supply piping system during any pressure testing of the system at
test pressures in excess of 1/2 psi (3.5 kPa). The water heater must be
isolated from the gas supply piping system by closing its manual shutoff
valve during any pressure testing of the gas supply system at test
pressures equal to or less than 1/2 psi (3.5 kPa). The supply line must be
capped when not connected to the water heater.
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