A.O. Smith VB/VW-500 - Manual (Page 12)

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communicating with the outdoors. The installation instructions for
confined spaces in tightly constructed buildings must be followed to
ensure adequate air supply.
CONFINED SPACE
When drawing combustion and dilution air from inside a conventionally
constructed building to a confined space, such a space shall be provided
with two permanent openings, ONE IN OR WITHIN 12 INCHES
(305mm) OF THE ENCLOSURE TOP AND ONE IN OR WITHIN 12
INCHES (305mm) OF THE ENCLOSURE BOTTOM. Each opening
shall have a free area of at least one square inch per 1000 Btu/hr
(2,225mm
2 per kw) of the total input of all appliances in the enclosure,
but not less than 100 square inches (645cm 2 ).
If the confined space is within a building of tight construction, air for
combustion, ventilation and draft hood dilution must be obtained
from outdoors. When directly communicating with the outdoors or
communicating with the outdoors through vertical ducts, two
VENTING
permanent openings, located in the aforementioned manner, shall
be provided. Each opening shall have a free area of not less than
one square inch per 4000 Btu/hr (551mm
2 per kw) of the total input
of all appliances in the enclosure. If horizontal ducts are used, each
opening shall have a free area of not less than one square inch per
2000 Btu/hr (1,101mm
2 per kw) of the total input of all appliances in
the enclosure.
Where power vented equipment is used in the same room as the
boiler, sufficient air openings must be supplied.
UNDERSIZED OPENINGS MAY RESULT IN INSUFFICIENT AIR FOR
COMBUSTION.
Where an exhaust fan is installed in the same room with the
boiler, sufficient openings for air must be provided in the walls.
UNDERSIZED OPENINGS WILL CAUSE AIR TO BE DRAWN
INTO THE ROOM THROUGH THE CHIMNEY OR OTHER
OPENINGS, CAUSING POOR COMBUSTION. SOOTING MAY
RESULT WITH AN INCREASED RISK OF ASPHYXIATION.
Additional care must be exercised to assure proper draft. For proper
operation, a minimum draft of -0.02” W.C. and a maximum draft of
-0.04” W.C. is recommended when vertically vented. Draft should
be measured 2 feet (0.6m) above the boiler vent collar.
VENT SIZING, INSTALLATION AND TERMINATION SHALL
BE IN ACCORDANCE WITH THIS INSTALLATION MANUAL.
ALL ELECTRICAL POWER AND GAS MUST BE TURNED OFF
PRIOR TO ANY INSTALLATION OF THE VENTING SYSTEM.
SPECIAL INSTALLATION CONSIDERATIONS
This boiler is a category IV appliance that can be vented using room
air for intake combustion air, or direct vented so that all intake air for
combustion comes from the outside through a sealed pipe. When
installing this appliance as direct vent, special vent kits are required.
In cold climates any water vapor remaining in the flue gases will condense
into a cloud of vapor at the point where the vent system exits the building.
Special consideration is recommended, before locating the vent
termination near walkways, windows and building entrances.
Direct venting into dead spaces such as alleys, atriums, and inside
corners can cause recirculation of flue gases. Recirculation of
flue gases will cause sooting, premature failure of the heat
exchanger, and icing of the combustion air intake during severe
cold weather. To prevent the recirculation of flue gases, maintain
as much distance as possible between the combustion air intake
and the exhaust vent terminal. Due to large volumes of flue gases,
multiple boiler applications also require additional distance between
the intake and exhaust terminals.
VENTING SYSTEM USING AL 29-4C ®
This boiler may be installed in four separate orientations depending
on the requirements of the building and the appliance. The installer
must decide which method is most appropriate for each installation.
These orientations are:
1. Vertical Termination - vertical vent termination through un-
enclosed or enclosed areas with roof penetration, see Figure 11.
2. Through-the-Wall Termination (TWT) - horizontal vent
termination directly through an outside wall, see Figure 11A.
3. Horizontal Direct Vent - using TWT to exhaust flue products
and PVC piping to bring combustion air to the boiler from the
outside, see Figures 12 and 12C.
4. Vertical Direct Vent - using a vertical vent termination to exhaust
flue products and PVC piping to bring combustion air to the
boiler from outside, see Figures 12A and 12B.
GENERAL EXHAUST VENT INSTALLATION PROCEDURE
Prior to beginning the installation of the vent system, determine and
obtain all parts required for the installation. IF THIS INSTALLATION IS
A DIRECT VENT INSTALLATION A DIRECT VENT KIT IS REQUIRED.
REFER TO THE PARTS LIST FOR KIT NUMBER.
Proper operation of the boiler and venting system is dependent
upon use of all specified parts and installation techniques; both
safety and proper performance of the system may suffer if
instructions are not followed.
CONNECTING VENT TO BOILER
At the outlet of the boiler vent, see Figure 10, the AL 29-4C ® Vent
Boot-Tee and Boot-Tee Drain Cover must be used as the transition