Bryant 395CAV User Manual

service and

376CAV

maintenance procedures

GAS-FIRED
INDUCED-COMBUSTION FURNACE

NOTE: Read the entire instruction manual before performing any
service or maintenance.

This symbol → indicates a change since the last issue.
These procedures are for size 45,000 through 155,000 Btuh input

units.
Index Page

SAFETY CONSIDERATIONS..................................................1-2

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

PROCEDURE...........................................................................2

CARE AND MAINTENANCE................................................2-11

Air Filter Arrangement..........................................................2-3

Blower Motor and Wheel......................................................3-4

Cleaning Heat Exchanger......................................................4-5

Electrical Controls and Wiring .............................................5-6

Troubleshooting...................................................................6-11

Unit Wiring Diagram................................................................8

Service Label ............................................................................9

Troubleshooting Guide......................................................10-11

395CAV

Series G

Cancels: SP04-45 SP04-54

9-98

A94087

Fig. 1—Model 376CAV Horizontal

®

SAFETY CONSIDERATIONS

Installing and servicing heating equipment can be hazardous due to
gas and electrical components. Only trained and qualified person­nel should install, repair, or service heating equipment.

Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations must
be performed by trained service personnel. When working on
heating equipment, observe precautions in the literature, on tags,
and on labels attached to or shipped with the unit and other safety
precautions that may apply.

Follow all safety codes. In the United States, follow all safety

→

codes including the National Fuel Gas Code (NFGC) NFPA No.
54-1996/ANSI Z223.1-1996. In Canada, refer to the current
edition of the National Standard of Canada CAN/CGA-B149.1­and .2-M95 Natural Gas and Propane Installation Codes (NSC­NGPIC). Wear safety glasses and work gloves. Have fire extin­guisher available during start-up and adjustment procedures and
service calls.

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 symbol. DAN­GER identifies the most serious hazards which will result in severe
personal injury or death. WARNING signifies a hazard 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 is used to highlight
suggestions which will result in enhanced installation, reliability,
or operation.

.

—1—

ama

CANADIAN GAS ASSOCIATION

APPROVED

R

A94085

Fig. 3—Model 395CAV

Upflow

A94086

Fig. 2—Model 376CAV

Downflow

REGISTERED QUALITY SYSTEM

WARNING: The ability to properly perform mainte­nance on this equipment requires certain expertise, me­chanical skills, tools, and equipment. If you do not
possess these, do not attempt to perform any maintenance
on this equipment other than those procedures recom­mended in the User’s Manual. FAILURE TO FOLLOW
THIS WARNING COULD RESULT IN POSSIBLE
DAMAGE TO THIS EQUIPMENT, SERIOUS PER­SONAL INJURY, OR DEATH.

WARNING: Never store anything on, near, or in contact
with the furnace, such as:

1. Spray or aerosol cans, rags, brooms, dust mops,
vacuum cleaners, or other cleaning tools.

2. Soap powders, bleaches, waxes or other cleaning
compounds, plastic or plastic containers, gasoline, kero­sene, cigarette lighter fluid, dry cleaning fluids, or other
volatile fluids.

3. Paint thinners and other painting compounds, paper
bags, or other paper products.
A failure to follow this warning could result in corrosion
of the heat exchanger, fire, personal injury, or death.

ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS

PROCEDURE

CAUTION: Electrostatic discharge can affect electronic

components. Take precautions during furnace installation
and servicing to protect the furnace electronic control.
Precautions will prevent electrostatic discharges from
personnel and hand tools which are held during the
procedure. These precautions will help to avoid exposing
the control to electrostatic discharge by putting the
furnace, the control, and the person at the same electro­static potential.

1. Disconnect all power to the furnace. DO NOT TOUCH

THE CONTROL OR ANY WIRE CONNECTED TO THE
CONTROL PRIOR TO DISCHARGING YOUR BODY’S
ELECTROSTATIC CHARGE TO GROUND.

2. Firmly touch a clean, unpainted, metal surface of the
furnace chassis which is close to the control. Tools held in
a person’s hand during grounding will be satisfactorily
discharged.

3. After touching the chassis you may proceed to service the
control or connecting wires as long as you do nothing that
recharges your body with static electricity (for example; DO
NOT move or shuffle your feet, DO NOT touch un­grounded objects, etc.).

4. If you touch ungrounded objects (recharge your body with
static electricity), firmly touch furnace again before touch­ing control or wires.

5. Use this procedure for installed and uninstalled (un­grounded) furnaces.

6. Before removing a new control from its container, dis­charge your body’s electrostatic charge to ground to protect
the control from damage. If the control is to be installed in
a furnace, follow items 1 through 5 before bringing the
control or yourself into contact with the furnace. Put all
used AND new controls into containers before touching
ungrounded objects.

7. An ESD service kit (available from commercial sources)
may also be used to prevent ESD damage.

CARE AND MAINTENANCE

WARNING: Turn off the gas and electrical supplies to

the unit before performing any maintenance or service.
Follow the operating instructions on label attached to
furnace. A failure to follow this warning could result in
personal injury.

The minimum maintenance that should be performed on this
equipment is as follows:

1. Check and clean air filter each month or more frequently if
required. Replace if torn.

2. Check blower motor and wheel for cleanliness each heating
and cooling season. Clean and lubricate as necessary.

3. Check electrical connections for tightness and controls for
proper operation each heating season. Service as necessary.

CAUTION: As with any mechanical equipment, per­sonal injury can result from sharp metal edges, etc.,
therefore, be careful when removing parts.

A. Air Filter Arrangement

The air filter arrangement may vary depending on the application.
Refer to Table 1 or 2 for filter size information.

TABLE 1—FILTER SIZE INFORMATION FOR

DOWNFLOW/HORIZONTAL FURNACES (IN.)

FURNACE

CASING WIDTH

14-3/16 (2) 14 X 20 X 1 Cleanable

17-1/2 (2) 14 X 20 X 1 Cleanable

21 (2) 16 X 20 X 1 Cleanable

24-1/2 (2) 16 X 20 X 1 Cleanable

FILTER QUANTITY

AND SIZE

FILTER

TYPE

TABLE 2—FILTER SIZE INFORMATION FOR UPFLOW

FURNACES (IN.)

FURNACE

CASING WIDTH

14-3/16 (1) 16 X 25 X 1* (1) 14 X 25 X 1 Cleanable

17-1/2 (1) 16 X 25 X 1* (1) 16 X 25 X 1 Cleanable

21 (1) 16 X 25 X 1 (1) 20 X 25 X 1* Cleanable

24-1/2 (2) 16 X 25 X 1* (1) 24 X 25 X 1 Cleanable

* Factory-provided with the furnace. Filters may be field modified as required
by cutting and folding the frame as indicated on the filter.

FILTER QUANTITY AND SIZE

Side Return Bottom Return

FILTER

TYPE

For continuing high performance and to minimize possible equip­ment failure, it is essential that periodic maintenance be performed
on this equipment. Consult your local dealer as to the proper
frequency of maintenance and the availability of a maintenance
contract.

WARNING: Never operate unit without a filter or with
filter access door removed. A failure to follow this
warning could result in fire, personal injury, or death.

—2—









AIRFLOW

Fig. 4—Horizontal Filter Arrangement

AIRFLOW

INSTALLATION

POSITION

OF FILTERS

RETURN-AIR

PLENUM

ACCESS DOOR

Fig. 5—Downflow Filter Arrangement

1. Downflow/Horizontal
Each furnace requires 2 filters which are installed in the

return-air duct. (See Fig. 4 and 5.) To remove filters for
cleaning or replacement, proceed as follows:

a. Disconnect electrical power before removing blower

access door.

b. Remove 2 screws from front of door and remove blower

access door.

c. Reach up behind top plate, tilt filters toward center of

return-air plenum, remove filters, and clean as needed.
Replace if torn.

d. Furnaces are equipped with permanent, washable filters.

Clean filters with tap water. Spray water through filter in
opposite direction of airflow.

e. Rinse and let dry. Oiling or coating of filters is not

recommended or required.

f. Reinstall filters.

A94307

A88486

g. Replace blower access door.
h. Restore electrical power to furnace.

2. Upflow
Each furnace requires 1 or 2 filters which are installed in the

blower compartment. (See Fig. 6.) To remove filters for
cleaning or replacement, proceed as follows:

a. Disconnect electrical power before removing access

doors.
b. Remove blower and control access doors.
c. Release filter retainer from clip at front of furnace

casing. (See Fig. 6.) For side return, clips may be used on

either or both sides of the furnace.
d. Slide filter(s) out.
e. Furnaces are equipped with permanent, washable filters.

Clean filters with tap water. Spray water through filter in

opposite direction of airflow.
f. Rinse and let dry. Oiling or coating of filter is not

recommended or required.
g. Reinstall filter(s).
h. Replace blower and control access doors.
i. Restore electrical power to furnace.

B. Blower Motor and Wheel

For long life, economy, and high efficiency, clean accumulated dirt
and grease from the blower wheel and motor annually.

The following steps should be performed by a qualified service
technician.

Some motors have prelubricated sealed bearings and require no
lubrication. These motors can be identified by the absence of oil
ports on each end of the motor. For those motors with oil ports,
lubricate motor every 5 years if motor is used on intermittent
operation (thermostat FAN in AUTO mode), or every 2 years if
motor is in continuous operation (thermostat FAN in ON mode).

NOTE: Remember to disconnect the electrical supply before
removing access doors.

Clean and lubricate as follows:

1. Remove 2 screws from blower access door
(downflow/horizontal furnace only) and remove blower
access door.

2. Remove vent pipe enclosure (downflow/horizontal furnace
only) and disconnect short piece of vent pipe from relief
box.

3. Disconnect wires from auxiliary limit on blower housing
(downflow/horizontal furnace only).

4. Remove control.

5. Disconnect electrical leads from control. (See Fig. 6 or 7.)
Note location of wires for reassembly.

6. Remove screws holding blower assembly to blower deck
and slide blower assembly out of furnace.

7. Loosen screw in strap holding motor capacitor to blower
housing and slide capacitor out from under strap.

8. Mark blower wheel, motor, and motor support in relation to
blower housing before disassembly to ensure proper reas­sembly.

9. Loosen setscrew(s) holding blower wheel on motor shaft.

10. Remove bolts holding motor mount to blower housing and
slide motor and mount out of housing. Disconnect ground
wire attached to blower housing before removing motor.

11. Lubricate motor (when oil ports are provided).

—3—

MOUNTING







SCREWS

RELIEF

BOX

BLOCKED
VENT
SAFEGUARD

FLUE
COLLECTOR
BOX

AUXILIARY

LIMIT

SWITCH

(WHEN USED)

MOUNTING

SCREWS

VENT PIPE
ENCLOSURE

CONTROL

HUM

C

24V

OM

GRYW

BOARD

CONTROL

HUM

C

24V

OM

GRYW

FILTER
RETAINER

WASHABLE
FILTER

→ Fig. 6—Model 395CAV Upflow

a. Remove dust caps or plugs from oil ports located at each

end of motor.

b. Use a good grade of SAE 20 nondetergent motor oil and

put 1 teaspoon, 5 cc, 3/16 oz, or 16 to 25 drops in each
oil port. Do not over-oil.

c. Allow time for total quantity of oil to be absorbed by

each bearing.
d. Wipe excess oil from motor housing.
e. Replace dust caps or plugs on oil ports.

12. Remove blower wheel from housing.
a. Mark cutoff location to ensure proper reassembly.

b. Remove screws holding cutoff plate and remove cutoff

plate from housing.

c. Lift blower wheel from housing through opening.

13. Clean blower wheel and motor using a vacuum cleaner with
soft brush attachment. Do not remove or disturb balance
weights (clips) on blower wheel blades. The blower wheel
should not be dropped or bent as balance will be affected.

14. Reinstall blower wheel by reversing items 12 a through c.
Be sure wheel is positioned for proper rotation.

15. Reassemble motor and blower by reversing items 5 through

10. If motor has ground wire, be sure it is connected as
before.

CAUTION: Be sure the motor is properly positioned in
the blower housing. The motor oil ports must be at a
minimum of 45° above the horizontal centerline of the
motor after the blower assembly has been reinstalled in
the furnace.

16. Reinstall blower assembly in furnace.

17. Reinstall control. Connect blower electrical leads to control.
Please note that the common wire connection is 3/16 in. and
all other wire connections are 1/4 in. for assembly. DO
NOT FORCE.

18. Reconnect wires to auxiliary limit switch on blower housing
(downflow/horizontal furnace only).

19. Reinstall vent pipe and enclosure (downflow/horizontal
furnace only).

A98528

—4—

BLOCKED
VENT

RELIEF

SAFEGUARD

BOX

MANUAL
RESET LIMIT
SWITCHES

→ Fig. 7—Model 376CAV Downflow

20. Turn on electrical power and check for proper rotation and
speed changes between heating and cooling.

21. Replace blower access door. Secure with 2 screws
(downflow/horizontal furnace only).

C. Cleaning Heat Exchanger

The following steps should be performed by a qualified service
technician.

NOTE: Deposits of soot and carbon indicate the existence of a
problem which needs to be corrected. Take action to correct the
problem.

If it becomes necessary to clean the heat exchanger because of
carbon deposits, soot, etc., proceed as follows:

1. Turn off gas and electrical power to furnace.

2. Remove 2 screws from front of blower access door
(downflow/horizontal furnace only) and remove control and
blower access doors.

3. Remove vent pipe enclosure (downflow/horizontal furnace
only) and disconnect vent pipe from relief box.

4. Remove 2 screws that secure relief box. (See Fig. 6 or 7.)

5. Disconnect wires to the following components.

→

a. Blocked vent safeguard
b. Inducer motor
c. Pressure switch
d. Limit overtemperature switch(es)
e. Gas valve
f. Hot surface ignitor
g. Flame-sensing electrode
h. Two wiring connectors leading to control

6. Remove 8 screws that secure flue collector box to center
panel. Be careful not to damage sealant.

7. Remove complete inducer assembly from furnace, exposing
flue openings.

8. Clean cells using field-provided small wire brush, steel
spring cable, reversible electric drill, and vacuum cleaner.

a. Assemble wire brush and steel spring cable.

(1.) Use 48 in. of 1/4-in. diameter high-grade steel

spring cable (commonly known as drain clean-out
or Roto-Rooter cable).

A98529