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These clearances must be permanently
maintained. Clearances must also
accommodate an installation's oil, electrical,
and drain trap and drain line connections. If
the alternate ventlflue connections are used
additional clearance must be provided to
accommodate these conditions Section IX,
Vent Flue Pipe and Combustion Air Pipe for
details.
NOTE: In addition to the required
clearances to combustible materials, a
minimum of 24 inches service clearance
must be available in front of the unit.
A clearance of 24 inches at the rear of the
unit is also recommended.
Thermostat Location
The thermostat should be placed
apprOXimately five feet from the floor on a
vibration-free, inside wall in an area having
good air circulation. Do not install the
thermostat where it may be influenced by
any of the following:
o Drafts or dead spots behind doors,
in corners, or under cabinets.
o Hot or cold air from registers.
o
Radiant heat from the sun.
o Light fixtures or other appliances.
o Radiant heat from a fireplace.
o Concealed hot or cold water pipes,
or chimneys.
o
Unconditioned areas behind the
thermostat, such as an outside
wall.
V. COMBUSTION & VENTILATION AIR
REqUIREMENTS
! WARNING
. TO AVOID PROPERTY DAMAGE,
PERSONAL INJURY OR DEATH,
SUFFICIENT FRESH AIR FOR PROPER
COMBUSTION AND VENTILATION OF
FLUE GASES MUST BE SUPPLIED.
MOST HOMES REQUIRE OUTSIDE AIR
BE SUPPLIED INTO THE FURNACE
AREA.
Improved construction and additional
insulation in buildings have reduced heat
loss by reducing air infiltration and escape
around doors and windows. These changes
have helped in reducing heating/cooling
costs, but have created a problem supplying
combustion and ventilation air for burning
appliances.
Appliances that pull air out of the house
(exhaust fans, fireplaces, clothes dryers,
etc.) increase the problem by starving
appliances for air.
House depressurization can cause back
drafting or improper combustion of oil fired
appliances, thereby exposing building
occupants to combustion products that
could include carbon monoxide and cause:
1. Nausea-Headaches-Dizziness, Flu
Like symptoms.
2. Excessive humidity - heavily frosted
windows or a moist feeling in the
home.
3. Smoke from a fireplace will not draw
up the chimney.
4. Flue gases that will not draw up the
appliance vent pipe.
Combustion and Ventilation Air
Adequate provisions for combustion air,
ventilation of furnace, and dilution of the
gases must be made. When a furnace is
installed in an unconfined space in a
building, it can be assumed that infiltration
will be sufficient to supply the required air.
If the furnace is installed in a confined space
and combustion air is taken from the heated
space, the supply air and ventilating air must
be through two permanent openings of
equal area. A confined space is
U
a space
Whose volume is less than 50 cubic feet per
1000 BTU per hour of the combined input
rating of all appliances installed in that
space." One opening must be within 12" of
the ceiling and the other within 12" of the
floor. Each opening must have a minimum
free area of at least 1 square inch per 1000
BTU per hour of total input rating of all
appliances within the space but not less
than 100 square inches.
If the furnace is installed in a space within a
building of tight construction and air must be
supplied from outdoors. In this case, one
opening shall be within 12" of the ceiling and
the other within 12" of the floor.
If vertical combustion ducts are run, each
opening must have a free area of at least 1
square inch per 4000 BTU per hour.
If horizontal combustion ducts are run, 1
square inch per 2000 BTU per hour of the
total input of all appliances is required.
6
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