PREINSTALLATION
3.Chimney/Vent Operation: The vent system must be sized and installed to provide the draft needed to remove all combustion products. If the vent system does not provide enough draft, combustion products will spill into the building from the draft hood relief opening. If spillage of combustion products occurs, check the vent system, the combustion and ventilation openings and make sure the boiler room is never under negative pressure.
WARNING
Failure to provide adequate venting can result in severe property damage, personal injury or death.
4.Exterior Vents
a.If the vent is outside, make sure it is insulated sufficiently to ensure adequate draft.
5.Vent Sizing:
a.Individual vents: Use vent piping the same diameter as the boiler vent connection. The minimum height is 10 feet (305 cm) above the bottom of the draft hood (relief opening). The vent must also extend above the roof or any obstructions as outlined in the current edition of the National Fuel Gas Code, ANSI Z223.1/NFPA 54 and/or CAN/CGA B149, Installation Codes or as required by local codes.
b.Combined vent breeching:
•The recommended sizing in Section 14, Boiler Ratings & Dimensions, in this Manual is based on a minimum chimney or vent height of 20 feet (610 cm) and a maximum horizontal run of 6 feet (183 cm) to the chimney with no more than one
Figure 1.8: Vent Connection
•The minimum area of the chimney serving two or more appliances must be at least the area of the largest chimney connector plus 50% of the total area of all other appliance connectors.
•The vent connector must be single wall steel or Type B double wall vent pipe. The vent connector must be Type B double wall if it is located in or passes through cold areas. The vent connector must extend into, but not beyond, the inside wall of the chimney.
6.Vent Connection to Boiler (Figure 1.8):
a.Provide at least a 3 foot (91 cm) rise in the vent connection on the boiler.
b.The vent system should provide a draft of at least 0.02" w.c. (5 Pa) measured at the vent connections.
c.Support the weight of the vent system independently of the boiler draft hood. The draft hood is not designed to carry structural loading.
d.Provide support of the vent connector (breeching) at maximum 12 foot (366 cm) intervals to prevent sagging and to provide a minimum upward slope of 1/4" per foot (21 mm per meter).
e.Do not connect the vent for this boiler into any vent system which operates with positive pressure.
f.Use Type B
7.Removing an existing boiler from a common vent: At the time for removal of an existing boiler, the following steps shall be followed with each appliance connected to the common venting system placed in operation, while the other appliances remaining connected to the common venting system are not in operation.
a.Seal any unused openings in the common venting system.
b.Visually inspect the venting system for proper size and horizontal pitch and determine there is no blockage or restriction, leakage, corrosion and other deficiencies which could cause an unsafe condition.
c.Insofar as is practical, close all building doors and windows and all doors between the space in which the appliances remaining connected to the common venting system are located and other spaces of the building. Turn on clothes dryers and any appliance not connected to the common venting system. Turn on any exhaust fans, such as range hoods and bathroom exhausts, so they will operate at maximum speed. Do not operate a summer exhaust fan. Close fireplace dampers.
d.Place in operation the appliance being inspected. Follow the lighting instructions. Adjust the thermostat so appliance will operate continuously.
e.Test for spillage at the draft hood relief opening after 5 minutes of main burner operation. Use the flame of a match or candle, or smoke from a cigarette, cigar or pipe.
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