Bryant CONDENSING GAS FURNACE 355MAV Installation, Start-Up, And Operating Instructions Manual Download

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NOTE:

For upflow/downflow applications install furnace so that

it is level or pitched forward within 1/2-in. for proper furnace
operation. For horizontal applications pitch 1/4-in. minimum to
1/2-in. maximum forward to ensure proper condensate drainage
from secondary heat exchangers. (See Fig. 14.)

When a furnace is installed so that supply ducts carry air circulated
by the furnace to areas outside the space containing the furnace,
the return air shall also be handled by ducts sealed to furnace
casing. The ducts terminate outside the space containing the
furnace to ensure there will not be a negative pressure condition
within equipment room or space.

WARNING:

FIRE, INJURY OR DEATH HAZARD

Failure to follow this warning could result in fire,
property damage, personal injury, or death.
Do not install furnace on its back. (See Fig. 15.) Safety
control operation will be adversely affected. Never con-
nect return-air ducts to back of furnace.

CAUTION:

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.

CAUTION:

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. 16.)

II.

LOW-HEAT ONLY INSTALLATION

This 355MAV 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. 32 and Table
9. With this setup, high-heat operation will not occur.

CAUTION:

UNIT DAMAGE HAZARD

Failure to follow this caution may result in minor
property or unit damage.
The furnace can operate in the high-heat mode when
certain fault conditions occur. The following precautions
should be taken:
1. Size gas piping based on the high-heat input.
2. Check the high-heat input and adjust it per the main

literature instructions.

Fig. 14—Proper Condensate Drainage

A02146

UPFLOW OR DOWNFLOW

HORIZONTAL

FRONT

LEVEL (0

″

)

⁄

″

MAX