Sidewall Venting; Venting System - A.O. Smith HW 300 Instruction Manual

Test for spillage at the draft hood relief opening after five minutes
of main burner operation. Use the flame of a match or candle.
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 any other gas burning appliance to their
previous conditions of use.
Any improper operation of the common venting system should be
corrected so the installation conforms with the current edition of
National Fuel Gas Code, ANSI Z223.1 or CAN/CSA B149.1. 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 the National Fuel
Gas Code, ANSI Z223.1 or CAN/CSA B149.1.
MULTIPLE VENT TABLE
Table 14 on Page 23 has been compiled to show the material
sizes in a Type B doublewall combined vent system. Refer to
the current edition of NFPA 54 or CAN/CSA B140.1 for further
information.
A combined vent system is one in which two or more boilers at
one level are attached to a common vent.
In order to use Table 14, the connector rise and total vent height
must be known. Connector rise is vertical distance from the draft
hood outlet to the point where the manifold connection is made. Total
vent height is the least vertical distance from a draft hood outlet to
the top of the vent. Local codes or utility requirements often govern
termination height. ULC listed doublewall gas vents, up through 24"
(610 mm) diameter, can be installed in heated and unheated areas
and can pass through floors, ceilings, partitions, walls and roofs,
provided the required one inch clearance is observed. These vents
should be installed in accordance with National Fuel Gas Code,
ANSI Z223.1 or CAN/CSA B149.1.
ExAMPLE SHOWING USE OF THE HW-670 COMBINED
VENT SIZING TABLE
FIGURE 16. ExAMPLE FOR COMBINED VENT SIZING
TABLE

SIDEWALL VENTING

The optional sidewall power vent system is certified for maximum
100' equivalent venting. The power vent kits p/n for HW300, 399-
420, 520, 670 are 325614-000, 325614-001, 325614-002 and
325614-003 respectively. If you are installing the optional power
vent kit, refer to your HW Power Vent Kit Installation Instructions
for proper wiring and installation procedures. Contact your local
A.O.Smith representative for details.

VENTING SYSTEM

Have venting system checked every six months for
obstructions and/or deterioration in vent piping. Refer to
Venting Maintenance on Page 41.
1. Insofar as is practical, close all doors, windows and air
inlets to the building. Turn on all exhaust fans (range
hood, bathroom exhaust, etc.) so they will operate at their
maximum speed. Close fireplace dampers.
2. After allowing the boiler to operate for five minutes, test for
spillage at the draft hood relief opening.
3. "Checking the draft. Operate vent connected gas utilization
equipment for several minutes and check to see that the
combustion products are going up the chimney or gas vent
properly by passing a lighted match or taper around the
edge of the relief opening of the draft hood. If the chimney or
gas vent is drawing properly, the match flame will be drawn
into the draft hood. If not, the combustion products will tend
to extinguish this flame.
If the combustion products are escaping from the relief opening
of the draft hood, do not operate the equipment until proper
adjustment or repairs are made to provide adequate draft through
the chimney or gas vent."
4. Next, turn on all other fuel burning appliances within the
same room so they will operate at their full input.
Repeat step C above, checking the draft on each appliance.
FIGURE 17. VENTING SYSTEM
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