(20)Flashing and storm collars.
(21)Guying or bracing of common vent pipe above roof.
(22)Securing and gas tightness of joints.
(23)Lightning arrester if top of metal vent is one of highest points on the roof.
Where choice is possible, many advantages can be listed for the UL Listed double wall metal type B vent:
1.Warm up is faster with type B vents than vents having greater mass.
2.Type B vents permit closer clearance to combustible material than single wall metal vents unless special precautions are taken with the latter.
3.Type B vents are less prone to condensation and corrosion than single wall metal vents.
4.Type B vents are lightweight, easy to handle and assemble.
WARNING
When an existing boiler is removed from a common venting system, the common venting system is likely to be too large for proper venting of the appliances remaining connected to it. At the time of removal of an existing boiler, the following steps shall be followed with each appliance remaining 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 dryer 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 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.
f.After it has been determined that each appliance remaining connected to the common venting system properly vents when tested as outlined above, return doors, windows, exhaust fans, fireplace dampers and other gas burning appliance to their previous conditions of use.
g.Any improper operation of the common venting system should be corrected so the installation conforms with the National Fuel Gas Code, ANSI Z223.1. When resizing any portion of the common venting system, the common venting system should be resized to approach the minimum size as determined using the appropriate tables in Chapter 10 in the National Fuel Gas Code, ANSI Z223.1.
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