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5790 733 - 07
Vitocrossal 300 CA3 Series 2.5 to 6.0 Installation/Service
Vent Requirements
WARNING
Failure to provide an adequate supply of fresh
combustion air can cause poisonous flue gases to
enter living space, which can cause severe personal
injury or loss of life.
CAUTION
Do not store chemicals containing chlorine or other
corrosive materials near the boiler, such as bleach,
cleaning solvents, detergents, acids, hair spray,
spray cans, paint thinners, paint, water softener
salt, perchloroethylene, or carbon tetra chloride.
Combustion air supply, room air dependent application only
The Vitocrossal 300, CA3 boiler requires fresh air for safe
operation and must be installed in a mechanical room
where there are provisions for adequate combustion and
ventilation air.
Provisions for combustion and ventilation air must be
made in accordance with CAN/CSA-B149.1 or .2 Natural
Gas Installation Codes (latest edition) (for installations in
Canada) or in accordance with sections for Combustion
and Ventilation Air, of the National Fuel Gas Code, ANSI
Z223.1 (latest edition) or applicable provisions of local
codes (for installations in the U.S.A.)
Follow local codes to properly isolate the vent pipe when
passing through floors, ceilings and roof.
Whenever possible, install boiler near an outside wall so
that it is easy to duct fresh air directly to the boiler area.
Refer to national codes for duct sizing. Round ducts may
be used.
The boiler must be vented and supplied with combustion
air and exhaust vents as described in this section. Ensure
the vent and combustion air supply comply with these
instructions.
The Vitocrossal 300, CA3 boiler location should never
be under negative pressure. Exhaust fans, attic fans, or
dryer fans may cause air to be exhausted at a rate higher
than the air can enter the structure for safe combustion.
Corrective action must be taken to ensure enough air is
available. Never cover the boiler or store debris or other
materials near the boiler, or in any way block the flow of
adequate fresh combustion air to the boiler.
If boiler is installed in a confined space (a space with a
volume of less than 50 cubic feet per 1000 Btu/h of gas
input for all fuel burning equipment) or building layout
is unusually tight, adequate air for combustion must be
provided by two openings: one located about 6 in. below
the ceiling, the other about 6 in. above the floor. When
communicating directly with the outside, each opening
must have a minimum free area of one square inch per
2000 Btu/h of gas input. When all combustion air is
provided by openings in doors, etc. to adjoining spaces
having adequate infiltration, each opening must have a
minimum free area of one square inch per 1000 Btu/h
of gas input, but not less than 100 in
2
.
You must know the free area of louvers used to cover
up the combustion and ventilation openings in closet
installations. If you do not know the free area, assume
20% for wood louvers and 60-75% free area for metal
louvers. When using louvers, the openings have to be
made larger.
For example, a free 14 in. x 6 in. (356 mm x 152 mm)
opening becomes a 14 in. x 10 in. (356 mm x 254 mm)
opening for a grill containing metal louvers.
Venting
