UNIT DAMAGE HAZARD
This gas furnace may be used for construction heat provided
that:
-The furnace is permanently installed with all electrical
wiring, piping, air filters, venting and ducting installed
according to these installation instructions. A return air duct
is provided, sealed to the furnace casing, and terminated
outside the space containing the furnace. This prevents a
negative pressure condition as created by the circulating air
blower, causing a flame rollout and/or drawing combustion
products into the structure.
-The furnace is controlled by a thermostat. It may not be
″
hot
wired
″
to provide heat continuously to the structure without
thermostatic control.
-Clean outside air is provided for combustion. This is to
minimize the corrosive effects of adhesives, sealers and other
construction materials. It also prevents the entrainment of
drywall dust into combustion air, which can cause fouling and
plugging of furnace components.
-The temperature of the return air to the furnace is maintained
between 55°F (13°C) and 80°F (27°C), with no evening
setback or shutdown. The use of the furnace while the
structure is under construction is deemed to be intermittent
operation per our installation instructions.
-The air temperature rise is within the rated rise range on the
furnace rating plate, and the firing rate has been set to the
nameplate value.
-The filters used to clean the circulating air during the
construction process must be either changed or thoroughly
cleaned prior to occupancy.
-The furnace, ductwork and filters are cleaned as necessary to
remove drywall dust and construction debris from all HVAC
system components after construction is completed.
-After construction is complete, verify furnace operating
conditions including ignition, input rate, temperature rise and
venting, according to the manufacturer’s instructions.
The furnace and its return air system shall be designed and
installed so that negative pressure created by the air circulating fan
cannot affect another appliance’s combustion air supply or act to
mix products of combustion with circulating air, and that the air
circulating fan of the furnace, if installed in an enclosure commu-
nicating with another fuel-burning appliance not of the direct-vent
type, shall be operable only when any door or panel covering an
opening in the furnace fan compartment or in a return air plenum
on ducts is in the closed position.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in minor property or
unit damage.
If these furnaces are installed in an unconditioned space
where ambient temperatures may be 32°F or lower, freeze
protection measures must be taken. (See Fig. 17.)
Step 2—Low-Heat Only Installation
This 58MVB furnace can be installed to operate in the low-heat
only heating mode when sized using the low-heat heating capacity.
This is accomplished by placing setup switch SW1-2 in the ON
position to provide only low-heat operation. See Fig. 37 and Table
13. With this setup, high-heat operation will not occur.
Fig. 16—Prohibit Installation on Back
A93043
FRONT
BACK
FRONT
B
A
C
K
Fig. 17—Freeze Protection
A93058
32
°
F MINIMUM INSTALLED
AMBIENT OR FREEZE
PROTECTION REQUIRED
15
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