Gas Piping - A.O. Smith GCVT-40 Instruction Manual

There must be a minimum of 6 inches (153 mm) clearance between
single wall vent pipe and any combustible material. Fill and seal any
clearance between single wall vent pipe and combustible material with
mortar mix, cement, or other noncombustible substance. For other
than single wall, follow vent pipe manufacturer's clearance
specifications. To insure a tight fit of the vent pipe in a brick chimney,
seal around the vent pipe with mortar mix cement.
Failure to have required clearances between vent piping and combustible
material will result in a fire hazard.
Be sure vent pipe is properly connected to prevent escape of dangerous
flue gases which could cause deadly asphyxiation.
Chemical vapor corrosion of the flue and vent system may occur if air
for combustion contains certain chemical vapors. Spray can
propellants, cleaning solvents, refrigerator and air conditioner
refrigerants, swimming pool chemicals, calcium and sodium chloride,
waxes, bleach and process chemicals are typical compounds which
are potentially corrosive.

GAS PIPING

Make sure the gas supplied is the same type listed on the model rating
plate. The inlet gas pressure must not exceed 14 inch water column
(2.6 kPa) for natural and propane gas (L.P.). The minimum inlet gas
pressure shown on the rating plate is that which will permit firing at
rated input.
If the gas control valve is subjected to pressures exceeding 1/2 pound
per square inch (3.5 kPa), the damage to the gas control valve could
result in a fire or explosion from leaking gas.
If the main gas line Shut-off serving all gas appliances is used, also
turn "off" the gas at each appliance. Leave all gas appliances shut
"off" until the water heater installation is complete.
A gas line of sufficient size must be run to the water heater. Consult
the current edition of National Fuel Gas Code ANSI Z223.1/NFPA 54 and
your gas supplier concerning pipe size.
There must be:
• A readily accessible manual shut off valve in the gas supply line
serving the water heater, and
• A drip leg (sediment trap) ahead of the gas control valve to help
prevent dirt and foreign materials from entering the gas control valve.
• A flexible gas connector or a ground joint union between the shut off
valve and control valve to permit servicing of the unit.
Be sure to check all the gas piping for leaks before lighting the water
heater. Use a soapy water solution, not a match or open flame. Rinse
off soapy solution and wipe dry.
Water heaters covered in this manual have been tested and approved
for installation at elevations up to 7,700 feet (2,347 m) above sea level.
For installation above 7,700 feet (2,347 m), the water heater's Btu input
should be reduced at the rate of 4 percent for each 1,000 feet (305 m)
above sea level which requires replacement of the burner orifice in
accordance with the National Fuel Gas Code ANSI Z223.1/NFPA 54.
Contact your local gas supplier for further information.
Failure to replace the standard orifice with the proper high altitude
orifice when installed at elevations above 7,700 feet (2,347 m) could
result in improper and inefficient operation of the appliance, producing
carbon monoxide gas in excess of the safe limits. This could result in
serious injury or death. Contact your local gas supplier for any specific
changes that may be required in your area.
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