USER’S INFORMATION MANUAL
MODEL 345MAV
CONDENSING GAS FURNACE
NOTE TO INSTALLER:
This manual must be left with the equipment user.
As an ENERGY STAR® Partner,
Bryant Heating & Cooling
Systems has determined that
this product meets the ENERGY
STAR® guidelines for energy
efficiency.
WARNING: If the information in this manual is
not followed exactly, a fire or explosion may result
causing property damage, personal injury or loss
of life.
— Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any
other appliance.
— WHAT TO DO IF YOU SMELL GAS:
— Do not try to light any appliance.
— Do not touch any electrical switch; do not use
any phone in your building.
• Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
• If you cannot reach your gas supplier, call the
fire department.
— Installation and service must be performed by a
qualified installer, service agency or the gas
supplier.
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FURNACE COMPONENTS
13
14
1
Burner sight glass for viewing burner flame.
1
2
3
4
5
6
2
Burner assembly (inside). Operates with energy-
saving inshot burners and hot surface ignitor for safe,
dependable heating.
3
4
Combustion-air intake connection (right or left side).
6
Redundant gas valve. Safe, efficient. Features 1 gas
control with 2 internal shutoff valves.
7
8
9
15
16
5
6
Junction box for 115-v electrical power supply.
Vent outlet. Uses PVC pipe to carry vent gases from
the furnace’s combustion system (right or left side).
10
17
18
19
7
Secondary condensing heat exchanger (inside).
Wrings out more heat through condensation.
Constructed with polypropylene-laminated steel to
ensure durability.
11
12
8
9
Pressure switch ensures adequate flow of flue
products through furnace and out vent system.
Inducer motor. Pulls hot flue gases through the heat
exchangers, maintaining negative pressure for added
safety.
MODEL 345MAV FURNACE
(SHOWN IN UPFLOW POSITION)
2
10
11
Condensate drain connection. Collects moisture
condensed from burned gases for disposal into home
drain system.
Heavy-duty blower. Circulates air across the heat
exchangers to transfer heat into the home.
12
13
Air filter and retainer.
Rollout switch (manual reset) to prevent
overtemperature.
14
Primary serpentine heat exchanger (inside).
Stretches fuel dollars with the S-shaped heat-flow
design. Solid construction of corrosion-resistant
aluminized steel means reliability.
15
16
3-amp fuse provides electrical and component
protection.
Light emitting diode (LED) on control center. Code
lights are for diagnosing furnace operation and
service requirements.
17
18
19
Control center.
Blower access panel safety interlock switch.
Transformer (24v) behind control center provides
low-voltage power to furnace control center and
thermostat.
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NOTE: The qualified installer
or agency must use only factory-
authorized replacement parts, kits,
and accessories when modifying this
product.
IMPORTANT FACTS
STARTING YOUR
FURNACE
Your gas furnace uses air adjacent to the
furnace for combustion and vents to the
outside. Do not enclose it in an airtight
room or seal it behind solid doors. It
must have adequate airflow for efficient
combustion and safe ventilation. The
vent pipe must terminate outside the
structure and must not be obstructed in
any way.
Instead of a continuously burning pilot
flame which wastes valuable energy,
your furnace uses an automatic, hot
surface ignition system to light the
burners each time the thermostat
starts your furnace. Follow these
important safeguards:
4
This furnace contains SAFETY
DEVICES which must be MANU-
ALLY RESET. If the furnace is left un-
attended for an extended period of
time, have it checked periodically for
proper operation. This precaution will
prevent problems associated with no
heat, such as frozen water pipes, etc.
See “Before You Request a Service
Call” section in this manual.
5
• Never attempt to light the burners
manually with a match or other source
of flame.
3
To minimize the possibility of serious
personal injury, fire, damage to
your furnace, or improper operation,
carefully follow these safety rules:
• Read and follow the operating
instructions on the furnace, especially
the item that reads as follows:
• Keep the area around your furnace
free of combustible materials, gasoline,
and other flammable liquids and vapors.
• Do not cover the furnace, store trash
or debris near it, or in any way block
the flow of fresh air to the unit.
• Combustion air must be clean and
uncontaminated with chlorine or fluo-
rine. These compounds are present in
many products around the home, such
as: water softener salts, laundry
bleaches, detergents, adhesives, paints,
varnishes, paint strippers, waxes, and
plastics.
Make sure the combustion air for your
furnace does not contain any of these
compounds. During remodeling be
sure the combustion air is fresh and
uncontaminated. If these compounds
are burned in your furnace, the heat
exchangers may deteriorate.
• A furnace installed in an attic or
other insulated space must be kept
free and clear of insulating material.
Examine the furnace area when install-
ing the furnace or adding more insula-
tion. Some insulation materials may be
combustible.
Wait 5 minutes to clear out any
gas. Then smell for gas, including
near the floor. If you smell gas,
STOP! Follow “B” in the safety
information above on this furnace
label. If you don’t smell gas, go to the
next step.
SAFETY
CONSIDERATIONS
Installing and servicing of heating
equipment can be hazardous due to
gas and electrical components.
Only trained and qualified personnel
should install, repair, or service heat-
ing equipment.
• If a suspected malfunction occurs
with your gas control system, such as
the burners not lighting when they
should, refer to the shutdown proce-
dures on the furnace, or in the “Shut-
ting Down Your Furnace” section
and call your dealer as soon as
possible.
Untrained personnel can perform
basic maintenance functions such as
cleaning and replacing air filters. All
other operations must be performed
by trained service personnel. Observe
safety precautions in this manual, on
tags, and on labels attached to the fur-
nace and other safety precautions that
may apply.
!
WARNING
If overheating occurs or the
gas valve fails to shut off the
gas supply, turn off the man-
ual gas valve to the furnace
BEFORE turning off the elec-
trical supply. (See Fig. 7.) Fail-
ure to follow this warning
could result in a fire or explo-
sion, and personal injury or
death.
Recognize safety information. This is
!
the safety-alert symbol
. When you
see this symbol on the furnace and in
instructions or manuals, be alert to the
potential for personal injury.
Understand the signal words DANGER,
WARNING, and CAUTION. These
words are used with the safety-alert sym-
bol. DANGER identifies the most seri-
ous hazards which will result in severe
personal injury or death. WARNING
signifies hazards which could result in
personal injury or death. CAUTION is
used to identify unsafe practices which
would result in minor personal injury or
product and property damage.
NOTE: Do not use this furnace if any
part has been under water. Immedi-
ately call a qualified service technician
to inspect the furnace and to replace
any part of the control system and any
gas control which has been under
water.
CHECK AIR FILTER: Before
attempting to start your furnace, be
sure the furnace air filter is clean and in
place. See “Performing Routine Main-
tenance” section in this manual.
Then proceed as follows:
4
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7.Replace main furnace door.
(See Fig. 14.)
8.Turn on electrical supply to the fur-
nace and wait 1 minute.
(See Fig. 15.)
STEPS FOR STARTING
YOUR FURNACE
1. Set your room thermostat to the low-
est temperature setting. (See Fig. 6.)
1
M
3
O
F
F
P
2
C
ON
9.Open the external manual gas
valve. (See Fig. 16.)
®
10.Set room thermostat to a tem-
perature slightly above room
temperature. This will auto-
matically signal the furnace to
start.
11.When the furnace receives the start
signal, the inducer is started. When
the pressure switch verifies that
there is sufficient combustion air, the
control energizes the hot surface
ignitor. After the hot surface ignitor
is heated for 17 sec, the gas valve
permits gas to flow to the main burn-
ers. After ignition and a time delay
of 60 sec, the furnace blower starts.
12
6
13
NOTE:If the burners fail to ignite after
4 attempts, the furnace control system
will lock out. If lockout occurs, main
burners fail to light, or blower does not
come on, shut down the furnace and
call your dealer for service.
7
12. Set your thermostat to the temper-
ature that satisfies your comfort
requirements.
9
SUGGESTION: Setting the ther-
mostat back a few degrees and
compensating for the difference
with warmer clothing can make a
big difference in your fuel con-
sumption on extremely cold days.
The few degrees at the top of your
thermostat “comfort level” are the
most costly degrees to obtain.
1
M
3
O
F
F
P
2
C
ON
8
2.Close the external manual gas
valve. (See Fig. 7.)
3.Turn off electrical supply to the fur-
nace. (See Fig. 8.)
4.Remove the main furnace door.
(See Fig. 9.)
When room temperature drops
below the temperature selected
on the thermostat, the furnace
will be switched on automatically.
When room temperature reaches
the degree selected on the thermo-
stat, the furnace will be switched
off automatically.
10
5.Gas valve will have EITHER a con-
trol switch or control knob to turn
OFF or ON. Turn control switch or
knob on the gas valve to the OFF
position and wait 5 minutes. (See
Fig. 10 or 11.) Then smell for gas,
including near the floor. If you
smell gas, STOP! Follow operating
instructions on main furnace door.
6.After waiting 5 minutes, turn con-
trol switch or knob on the gas valve
to the ON position.
Some thermostats have a FAN
mode with 2 selections, AUTO
and ON. When thermostat is set
to AUTO, the furnace blower
cycles on and off, controlled by
the thermostat. In ON mode, the
furnace blower runs continu-
ously. This keeps the temperature
level in your home more evenly
balanced. It also continuously fil-
ters the indoor air.
11
(See Fig. 12 or 13.)
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PERFORMING
ROUTINE
MAINTENANCE
With proper maintenance and care, your
furnace will operate economically and
dependably. Instructions for basic main-
tenance are found on this and the follow-
ing pages. However, before beginning
maintenance, follow these safety pre-
cautions:
18
The following procedures must be
followed:
!
WARNING
Turn off electrical power sup-
ply to your furnace before re-
moving the main furnace door
to service or perform mainte-
nance. Failure to follow this
warning could result in per-
sonal injury or death.
1. Set your room thermostat to the
lowest temperature setting.
(See Fig. 17.)
2. Close the external manual gas
valve. (See Fig. 7.)
3. Turn off electrical supply to the
furnace. (See Fig. 18.)
4. Remove main furnace door.
(See Fig. 9.)
5. Turn control switch or knob on the
gas valve to OFF position.
(See Fig. 19 or 20.)
6. Replace main furnace door.
(See Fig. 14.)
7. If the furnace is being shut down
because of a malfunction, call
your dealer as soon as possible.
14
!
CAUTION
Although special care has
been taken to minimize sharp
edges, be extremely careful
when handling parts or reach-
ing into the furnace.
15
FILTERING OUT
TROUBLE
!
CAUTION
Adirtyairfilterwillcausealossofairflow
in your duct system. When excessive loss
of airflow occurs, the furnace may cycle
on its safety controls. If this condition is
left unattended, the furnace will eventu-
ally lock out. It is recommended that the
furnace air filter be checked every 3 or 4
weeks and cleaned if necessary.
Furnace is not to be installed,
operated, and then turned off
and left turned off in an unoc-
cupied structure during winter.
(See winterizing procedures in
maintenance section.)
16
SHUTTING DOWN
YOUR FURNACE
!
CAUTION
1
M
Never operate your furnace
without the air filter in place.
Doing so may damage the fur-
nace blower motor. An accu-
mulation of dust and lint on
internal parts of your furnace
can cause a loss of efficiency.
Should you need to shut down your
furnace for service or maintenance,
3
O
F
F
P
2
C
ON
you will need to turn the furnace off.
®
The air filter is normally located in the
blower compartment. (See Fig. 2.)
If air filter has been installed in another
location, contact your dealer for
instructions. To inspect, clean, and/or
replace the air filter(s), follow these
steps:
19
1. Turn off electrical supply to the
furnace. (See Fig. 18.)
2. Remove main furnace door.
(See Fig. 21.)
3. Remove blower access panel.
(See Fig. 22.)
17
20
6
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27
25
21
22
NOTE: It will be necessary to remove
2 screws.
4. Remove air filter from furnace.
• AIR FILTER(S) LOCATED IN
BOTTOM:
26
5. Inspect the filter. If torn, replace it.
NOTE: If washable filter that was
shipped with the furnace has been
replaced with an electronic air cleaner
(EAC), refer to the EAC Owner’s Man-
ual for maintenance information.
a. Slide filter retainer sideways until
it is free of latch. (See Fig. 23.)
b. Slide air filter out of furnace.
(See Fig. 24.)
28
COMBUSTION AREA
AND VENT SYSTEM
6. Wash filter (if dirty) in a sink,
bathtub, or outside with a garden
hose.Always use cold tap water.A
mild liquid detergent may be
used if necessary. Spray water
through filter in the opposite
direction of airflow. Allow filter
to dry.
Visually inspect the combustion area
and vent system before each heating
season. Make sure that all PVC pipes
leading into the combustion area and
vent are free from any cracks and sags.
Check the combustion-air intake adja-
cent to the furnace for blockage. Also
check the vent pipe on the outside of
your home for blockage.
7. Reinstall clean air filter.
8. Reinstall filter retainer.
9. Replace blower access panel and
main furnace door. Be sure to
replace 2 screws in blower access
panel. (See Fig. 27 and 28.) Turn
on electrical supply to the furnace.
If your furnace air filter needs to be
replaced, be sure to use the same size
and type of filter that was originally
supplied. Use the furnace filter table
and compare your furnace size with
the proper filter size.
23
When dirt, soot, scale, or rust is
allowed to build up, your furnace can
suffer a loss of efficiency and perform
improperly. Accumulations on the
main burners can result in firing out of
normal sequence. This delayed igni-
tion creates an alarmingly loud sound.
!
CAUTION
If your furnace makes an espe-
cially loud noise when the
main burners light, shut down
your furnace and call your
dealer.
FURNACE AIR FILTER TABLE
FURNACE
24
CASINGWIDTH FILTER SIZE*
• AIR FILTER LOCATED IN SIDE:
a. Remove filter retainer from latch.
(See Fig. 25.)
b. Gently remove air filter and care-
fully turn the dirty side up (if
dirty) to avoid spilling dirt from
the filter. (See Fig. 26.)
(IN.)
17-1/2
21
(IN.)
FILTERTYPE
Cleanable
Cleanable
Cleanable
(1) 16 x 25 x 1
(1) 20 x 25 x 1
(2) 16 x 25 x 1
24-1/2
To inspect the combustion area and
vent system, you will need a flashlight.
Refer to Fig. 2, and proceed as follows:
* Furnace with a side return-air inlet may have a dif-
ferent filter size. Measure the filter to obtain the
correct size.
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1. Turn off gas and electrical supplies
to the furnace and remove
the main furnace door. (See Fig. 7,
8, and 9.)
observe a suspected malfunction,
or the burner flames are not clear
blue, call your dealer.
6. Insert field-supplied funnel into tube.
2. Remove burner enclosure front.
(See Fig. 29 or 30.)
Inspect the gas burners and ignitor
area for dirt, rust, soot, or scale.
!
CAUTION
If dirt, rust, soot, or scale accu-
mulations are found, call your
dealer. Do not operate your
furnace.
31
HEADING SOUTH
FOR THE WINTER?
DON’T FORGET YOUR
FURNACE!
!
CAUTION
If the furnace is installed in an
unconditioned space where
the ambient temperatures may
be 32°F or lower, freeze protec-
tion measures must be taken.
32
29
Since the furnace uses a condensing
heat exchanger, some water will accu-
mulate in the unit as a result of the heat
transfer process. Therefore, once it
has been operated, it cannot be turned
off and left off for an extended period
of time when temperatures will reach
32° F or lower unless winterized. Fol-
low these procedures to winterize your
furnace:
30
3. Inspect the combustion-air and
vent pipes for sags, holes, cracks,
or disconnections.
1. Obtain propylene glycol (RV/
swimming pool antifreeze or
equivalent).
!
DANGER
If holes are found in the pipes
or if any portion has become
disconnected, toxic fumes
can escape into your home.
DO NOT OPERATE YOUR
FURNACE. Call your dealer for
service.
!
CAUTION
Do not use ethylene glycol
(Prestone II antifreeze coolant
or equivalent). Failure of plas-
tic components will occur.
33
7. Pour 1 quart of antifreeze into
funnel/tube.Antifreeze should run
through inducer housing, overfill
condensate trap, and flow into
open field drain. (See Fig. 33.)
8. Remove funnel and tube from
inducer housing and replace drain
connection cap and clamp.
2. Turn off electrical supply to the
furnace. (See Fig. 18.)
4. Reinstall burner enclosure front.
5. If your furnace is free of the above
conditions, replace main furnace
door and turn on electrical and gas
supplies to your furnace.
3. Remove main furnace door.
(See Fig. 21.)
4. Remove upper right inducer hous-
ing drain connection cap.
(See Fig. 32.)
(See Fig. 14, 15, and 16.)
6. Start the furnace and observe its
operation.Watch the burner flames
to see if they are clear blue, almost
transparent. (See Fig. 31.) If you
5. Connect field-supplied 1/2-in.
ID tube to upper inducer housing
drain connection.
9. Replace main furnace door.
(See Fig. 28.)
8
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• Inspect all condensate drain tubes
and condensate trap assembly for
leaks. The condensate removal system
should be cleaned annually by a quali-
fied service agency. Refer to the Ser-
vice and Maintenance Instructions for
further information.
NOTE: Turn off electrical supply
before continuing with checklist.
A CHECK-UP
CHECKLIST
Your furnace represents an important
investment in your family’s comfort
and your home’s value. To keep it
performing properly and as a preven-
tative tofuture problems, have a trained
service specialist give your furnace a
professional check-up annually. The
following checklist can be used as a
guideline to proper service:
• Is control switch or knob on gas
valve in ON position? (Follow start-up
procedures if you must reset switch or
knob to ON position.)
• Check manual reset flame rollout
switch located on the burner box.
(See Fig. 2.) If furnace has experienced
high temperature conditions, this
switch will shut off the furnace. Reset
it by pushing the button on the switch.
If it trips again, shut down the furnace
and call for service. See “Shutting
Down Your Furnace” section in this
manual.
• Examine the physical support of the
furnace. The support should be sound
with no cracks, sagging, gaps, etc.
around the base.
• Check furnace for any obvious signs
of deterioration.
• Inspect all flue gas passages, burn-
ers, heat exchangers, coupling
box(es), and inducer assembly.
BEFORE YOU
REQUEST A
SERVICE CALL
If your furnace is not operating or not
performing properly, you may save
the expense of a service call by check-
ing a few things yourself before calling
for service.
• Inspect all combustion-air and vent
piping inside structure and vent pipe
termination outside the structure.
• Check for obstructions around the
vent termination.
• Check gas pipes leading to and
inside of your furnace for leaks.
If your furnace still fails to operate, call
your service representative.
• Inspect and clean the blower motor
and wheel.
For your convenience, record the fur-
nace product and serial numbers on
page 2. Should you ever require ser-
vice, you will have ready access to the
information needed by your service
representative.
NOTE: The inducer and blower motors
are pre-lubricated and require no addi-
tional lubrication. These motors can be
identified by the absence of oil ports on
each end of the motor.
FOR INSUFFICIENT AIRFLOW:
• Check for dirty air filter(s).
• Check for blocked return-air or sup-
ply-air grilles throughout your home.
Ensure they are open and unobstructed.
• Inspect and change or clean air fil-
ter(s) if necessary.
This furnace has an LED operation
and fault code display to aid the
installer, service technician, or home-
owner while installing or servicing the
unit. The LED code can be seen by
removing the access door and viewing
LED(s) through the view port in the
blower access panel.
If problem still exists, call your dealer
for service.
• Inspect all supply- and return-air
ducts for obstructions, air leaks, and
insulation. Remedy any problem when
necessary.
IF FURNACE FAILS TO OPERATE:
Follow this checklist step by step,
advancing to the next step only if fur-
nace fails to start.
• Inspect the return-air duct connec-
tion(s) at the furnace to ensure it is
physically sound, sealed to the furnace
casing, and terminates outside the
space containing the furnace.
• Check thermostat for proper tem-
perature. Is thermostat set above room
temperature?
NOTE: Removing the blower access
panel or turning off the 115-v electrical
power supply will terminate LED diag-
nostic code display.
• Inspect electrical wiring, connec-
tions, and components for loose
connections.
• Is thermostat set to HEAT?
• Check fuses and circuit breakers. Is
electrical supply on?
• Perform an operational checkout to
determine whether your furnace is
working properly and if it requires
adjustments.
To decipher the meaning of the LED
code, and suggested action, the follow-
ing cross-reference can be used.
• Is manual shutoff valve in gas supply
pipe in open position? (Follow start-up
procedures if you open gas valve.)
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MODEL 345MAV DIAGNOSTIC CHART
(See Fig. 2.)
FAULT
CODE
FAULT CODE DESCRIPTION
CHECKLIST
Check for dirty air filter.
Check for blocked return-air or supply-air grilles.
13 or 33
Limit Switch Lockout
Check to be sure manual shutoff valve in gas supply pipe is in the open position. (Follow
start-up procedure if you open gas line.)
Ignition Lockout or
Ignition Proving Fault
NOTE:Turn off the electrical supply and remove access doors before continuing with this
checklist.
14 or 34
Check to be sure control switch or knob on gas valve is in ON position. (Follow start-up
procedures if you must reset switch or knob to ON position.)
24
31
Furnace Fuse Open
Check for blown fuse and possible short in 24-v wiring.
Check to make sure that all PVC pipes leading into the combustion-air intake and vent/
exhaust are free from any cracks and sags. Also check the combustion-air intake adjacent to
the furnace and vent/exhaust pipe on the outside of your home for blockage.
Pressure Switch Not Closed
12, 21, 22,
or 23
Any Other Fault Code
Call dealer for service.
No Fault
Code
Signaled
Check thermostat for proper temperature setting.
Check for blown fuses and circuit breakers.
Check to be sure blower access panel is properly in place.
Furnace Fails to Operate and No
Fault is Signaled
NOTES:
1. Light on continuously means control has power and working properly.
2. The fault code is a 2 digit number.The first digit is determined by the number of short flashes of the light and the second digit is determined by number of long
flashes of the light.
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Cancels: OM05-27
OM05-29
5-99
© 1999 Bryant Heating & Cooling Systems, 7310 W. Morris St., Indpls., IN 46231 12
Printed in U.S.A.
Catalog No. 5334-507
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