Installation Guide

11
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 return ductwork must be secured to
the furnace with sheet metal screws. For
installations in conned spaces, all return
ductwork must be adequately sealed. When
returnairisprovidedthroughthebottomofthe
furnace,thejointbetweenthefurnaceandthe
returnair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oororplatform.
Returnair and circulatingair ductworkmust
notbeconnectedtoanyotherheatproducing
devicesuchasareplaceinsert,stove,etc.This
mayresultinre,explosion,carbonmonoxide
poisoning,personalinjury,orpropertydamage.
Plenums&AirDucts
• Plenumsandairductsmustbeinstalledinaccordance
with the Standard for the Installation of Air Conditioning
and Ventilating Systems (NFPA No. 90A) or the
Standard for the Installation of Warm Air Heating and
Air Conditioning Systems (NFPA No. 90B).
• Tables4 & 5 (pages 27 - 29) contain the maximum
airflow and temperature rise data for each furnace input
rate. If the maximum airflow is 1,600 CFM or more, it is
recommended that two openings be used for return air
on upflow furnaces. Downflow furnaces can only use
one return opening.
• It is recommended that the outlet duct contain a
removable access panel. The opening should be
accessible when the furnace is installed in service and
shall be of a size that smoke or reflected light may be
observed inside the casing to indicate the presence of
leaks in the heat exchanger. The cover for the opening
shall be attached in such a manner as to prevent leaks.
• Ifoutside air is used as return air to the furnace for
ventilation or to improve indoor air quality, the system
must be designed so that the return air is not less than
60° F (15° C) during operation. If a combination of indoor
and outdoor air is used, the ducts and damper system
must be designed so that the return air supply to the
furnace is equal to the return air supply under normal,
indoor return air applications.
• When a cooling system is installed which uses the
furnace blower to provide airflow over the indoor coil,
the coil must be installed downstream (on the outlet
side) of the furnace or in parallel with the furnace.
• If a cooling system is installed in parallel with the
furnace, a damper must be installed to prevent chilled
air from entering the furnace and condensing on the heat
exchanger. If a manually operated damper is installed,
it must be designed so that operation of the furnace is
prevented when the damper is in the cooling position
and operation of the cooling system is prevented when
the damper is in the heating position.
• Seal all connections and joints with industrial grade
sealing tape or liquid sealant. Requirements for sealing
ductwork vary from region to region. Consult with local
codes for requirements specific to your area.
ReturnAirConnections
• In applications where the supply ducts carry heated
air to areas outside the space where the furnace is
installed, the return air must be delivered to the furnace
by duct(s) secured to the furnace casing, running full
size and without interruption. Donotusethebackof
thefurnaceforreturnair.
• Positionthefurnacewiththereturnairductworkensuring
even alignment of furnace (or coil casing) air opening
and return air duct. NOTE: The ductwork must have an
opening equal to that of the return air opening of the
furnace (or coil casing). See Figure 18 (page 26) for
return air opening size.
Upflow & Horizontal Furnaces
• The return air ductwork may be connected to the left
side, right side, or bottom of the furnace. NOTE: If
using the left or right side of the furnace for return air,
the bottom panel (Figure 18) must not be removed from
the bottom of the furnace.
wARNING:
The bottom panel of the furnace must be in
placewhenthefurnaceisinstalledwithside
returnairducts.Removalofallorpartofthe
basecould cause circulationof combustible
products into the living space and create
potentially hazardous conditions, including
carbonmonoxidepoisoningthatcouldresult
inpersonalinjuryordeath.
• SideReturnInstallations: To attach the return air duct
to the left or right side of the furnace, punch out the 4
knockouts from the side of the furnace (Figure 18).
CIRCULATING AIR REQUIREMENTS