FIGURE 18.
The vent pipe from the water heater must be no less than the diameter of the draft hood outlet on the water heater and must slope upward at least 1/4 inch per linear foot (21 mm per meter). See Figure 19.
FIGURE 19.
All vent gases must be completely vented to the outdoors of the structure (dwelling). Install only the draft hood provided with the new water heater and no other draft hood.
Vent pipes must be secured at each joint with sheet metal screws.
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 (3.5kPa) for natural and propane gas (L.P.) gas. The minimum inlet gas pressure listed on the rating plate is for the purpose of input adjustment. If the gas control valve is subjected to pressures exceeding 1/2 pound per square inch (3.5kPa), the damage to the gas control valve could result in a fire or explosion from leaking gas.
If the main gas line shutoff 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.
The minimum inlet gas pressure shown on the rating plate is that which will permit firing at the rated input.
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