14
Type "B" double-wall or equivalent vent pipe is recom-
mended. However, single-wall metal vent pipe may be
used as specified in the latest edition of the National
Fuel Gas Code
ANSI Z223.1.
Manifolds that connect more than one boiler to a com-
mon chimney must be sized to handle the combined
load. Consult available guides for proper sizing of the
manifold and the chimney. At no time should the area
be less than the area of the largest outlet.
At the time of removal of an existing boiler, the follow-
ing steps shall be followed with each appliance
remaining connected to the common venting system
placed in operation, while the other appliances remain-
ing 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 make sure there is no
blockage or restriction, leakage, corrosion and
other deficiencies which could cause an unsafe
condition.
(c) As much as possible, close all building doors and
windows and all doors between the space in which
the appliances remaining connected to the com-
mon 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
Fig. 15: Common Venting
hoods and bathroom exhausts, so they will oper-
ate 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 drafthood relief opening
after 5 minutes of main burner operation. Use the
flame of a match or candle, or smoke from a ciga-
rette, cigar or pipe.
(f) After it has been determined that each appliance
remaining connected to the common venting sys-
tem properly vents when tested as outlined above,
return doors, windows, exhaust fans, fireplace
dampers and any other gas burning appliance to
their previous conditions of use.
(g) Any improper operation of the common venting
system should be corrected so that the installation
conforms with the latest edition of the National
Fuel Gas Code, ANSI Z223.1. When re-sizing any
portion of the common venting system, the com-
mon venting system should be re-sized to
approach the minimum size as determined using
the appropriate tables in Part 11 of the National
Fuel Gas Code, ANSI Z223.1.
For special venting applications that require reduced
vent sizes and through-the-wall venting, the Type D
Induced Draft Assembly can be used. Consult the fac-
tory or your local Raypak representative.
5' MIN
2' MIN
10' OR LESS
2' MIN
VENT CAP
VENT PIPE
DRAFT HOOD
HEATER
Fig. 16: Venting Clearances