9
110547-01 - 4/20
FORCEVFO Installation & Service Manual
1. Determine volume of space (boiler room).
Rooms communicating directly with the
space in which the appliances are installed,
through openings not furnished with doors, are
considered a part of the space.
Volume(ft3) = Length(ft) x Width(ft) x Height(ft)
2. Determine total input of all appliances in the
space.
Add inputs of all appliances in the space and
round the result to the nearest 1000 BTU per
hour.
3. Determine type of space. Divide Volume by
total input of all appliances in space. If the
result is greater than or equal to 50 ft3/1000
BTU per hour, then it is considered an
unconfined space. If the result is less than
50 ft3/1000 BTU per hour then the space is
considered a confined space.
4. For boiler located in an unconfined space of a
conventionally constructed building, the fresh
air infiltration through cracks around windows
and doors normally provides adequate air for
combustion and ventilation.
5. For boiler located in a confined space or an
unconfined space in a building of unusually
tight construction, provide outdoor air.
a. Outdoor air may be provided with the
use of two permanent openings which
communicate directly or by duct with the
outdoors or spaces (crawl or attic) freely
communicating with the outdoors. Locate
one opening within 12 inches of top of
space. Locate remaining opening within
12 inches of bottom of space. Minimum
dimension of air opening is 3 inches. Size
each opening per following:
i. Direct communication with outdoors.
Minimum free area of 1 square inch
per 4,000 BTU per hour input of all
equipment in space.
ii. Vertical ducts. Minimum free area of
1 square inch per 4,000 BTU per hour
input of all equipment in space. Duct
cross-sectional area shall be same as
opening free area.
iii. Horizontal ducts. Minimum free area of
1 square inch per 2,000 BTU per hour
input of all equipment in space. Duct
cross-sectional area shall be same as
opening free area.
Alternate method for boiler located
within confined space.Use indoor air if
two permanent openings communicate
directly with additional space(s) of
sufficient volume such that combined
volume of all spaces meet criteria for
unconfined space. Size each opening
for minimum free area of 1 square inch
per 1,000 BTU per hour input of all
equipment in spaces, but not less than
100 square inches.
6. Louvers and Grilles of Ventilation Ducts
a. All outside openings should be screened
and louvered. Screens used should not be
smaller than 1/4 inch mesh. Louvers will
prevent the entrance of rain and snow.
b. Free area requirements need to consider
the blocking effect of louvers, grilles, or
screens protecting the openings. If the free
area of the louver or grille is not known,
assume wood louvers have 20-25 percent
free area and metal louvers and grilles have
60-75 percent free area.
c. Louvers and grilles must be fixed in the
open position, or interlocked with the
equipment to open automatically during
equipment operation.
NOTICE Clearance to venting is for single wall
vent pipe. If Type L vent is used, clearance may
be reduced to the minimum required by the vent
pipe manufacturer.
2Pre-Installation (continued)
WARNING
Adequate combustion and ventilation air must
be provided to assure proper combustion and
to maintain safe ambient air temperatures.
DO NOT install boiler where gasoline or other
flammable vapors or liquids, or sources of
hydrocarbons (i.e. bleaches, fabric softeners,
etc.) are used or stored.
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