MG2S Installation Manual

11
CIRCULATING AIR REQUIREMENTS
WARNING:
Do not allow combustion products to enter the
circulating air supply. Failure to prevent the
circulation of combustion products into the
living space can create potentially hazardous
conditions including carbon monoxide poisoning
that could result in personal injury or death.
All supply ducts must be secured to the furnace
with sheet metal screws and adequately sealed.
When supply air is provided through the bottom
of the unit, the joint between the furnace and the
plenum must be air tight.
The surface that the furnace is mounted on must
provide sound physical support of the furnace
with no gaps, cracks or sagging between the
furnace and the floor or platform.
Supply air ducts must not be connected to any
other heat producing device such as a fireplace
insert, stove, etc. This may result in fire, explosion,
carbon monoxide poisoning, personal injury, or
property damage.
Plenums & Air Ducts
This unit is designed only for use with a bottom supply
duct and must be installed in accordance with the
standards of the National Fire Protection Association
Standard for Installation of Air Conditioning Systems
(NFPA 90A), Standard for Installation of Residence Type
Warm Air Heating and Air Conditioning Systems (NFPA
90B), and all applicable local codes. NFPA publications
are available by writing to: National Fire Protection
Association, Batterymarch Park, Quincy, ME 02269 or go to
www.NFPA.org on the web.
• Design the air ducts according to methods described
by the Air Conditioning Contractors of America (ACCA).
• Gas piping must not run in or through any of the air
duct system.
• Air conditioning systems may require more duct register
and open louver area to obtain necessary airflow.
• Noncombustible pans having one inch upturned flanges
are located beneath openings in a floor return duct
system.
Supply Air Connections
• For proper air distribution, the supply duct system must
be designed so that the static pressure measured
external to the furnace does not exceed the listed static
pressure shown on the furnace rating plate. The supply
air must be delivered to the heated space by duct(s)
secured to the furnace casing, running full length and
without interruption.
• Duct system must be designed so that no supply
registers are located in duct system directly below the
furnace.
Return Air Connections
• Front return furnaces are factory configured for the
return air to flow through the front louvered door. The
return air may also be attached to either side of the
furnace cabinet using a field installed kit. The location
and size of the side and top return air connections are
shown in Figure 23 (page 29) & Figure 24 (page
30). The filter size for the side return air is 20” x 20”
x 1”.
• Top return furnaces are factory configured for the return
air to enter the top of the furnace. See Figure 24 (page
30).
NOTE: For top return installations, an external or in-
wall filter mount can be used. The factory installed
filter should be removed and the return duct should
be sized to provide adequate airflow.
• For floor return systems, the manufactured housing
manufacturer or installer shall affix a prominent marking
on or near the appliance where it is easily read when
the closet door is open. The marking shall read:
A Single trunk duct
B
Dual trunk duct
w/crossover connector
C
Transition duct
w/branches
Figure 6. Typical Supply Duct Systems
CAUTION, HAZARD OF ASPHYXIATION. DO NOT
COVER OR RESTRICT FLOOR RETURN AIR
OPENING.
• Return air openings should not be located to draw air
directly from a bathroom.
• Materials located in the return duct system shall have
a flame spread classification of 200 or less.
• The total free area of the openings in the floor or the
ceiling registers serving the return air duct system must
not be not less than 352 in
2
(2,270 cm
2
).
Closet & Alcove Installations
WARNING:
Failure to comply with the the following
instructions may result in fire, asphyxiation or
carbon monoxide poisoning.