Bryant Furnace 394HAD User Manual

service and  
394HAD  
396HAD  
Series C  
maintenance procedures  
GAS-FIRED  
INDUCED-COMBUSTION FURNACES  
Cancels: SP04-13  
SP04-19  
11-1-93  
NOTE: Read the entire instruction manual before starting the  
installation.  
These procedures are for sizes 65,000 through 150,000 Btuh units.  
CANADIAN GAS ASSOCIATION  
ama  
®
Index  
Page  
A PPROVED  
R
SAFETY CONSIDERATIONS.....................................................1  
CARE AND MAINTENANCE..................................................1-5  
Air Filter Arrangement..........................................................2-3  
Blower Motor and Wheel......................................................3-4  
Cleaning Heat Exchanger......................................................4-5  
Electrical Controls and Wiring.................................................5  
Pilot ...........................................................................................5  
Troubleshooting ........................................................................5  
Unit Wiring Diagram ............................................................6-7  
Troubleshooting Chart ..............................................................8  
SAFETY CONSIDERATIONS  
Installing and servicing heating equipment can be hazardous due to  
gas and electrical components. Only trained and qualified person-  
nel 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.  
A92058  
Fig. 1—Model 396HAD  
Downflow  
Follow all safety codes. In the United States, follow all safety  
codes including the National Fuel Gas Code NFPA No. 54-  
1992/ANSI Z223.1-1992 (NFGC). In Canada, refer to the current  
edition of the National Standard of Canada CAN/CGA-B149.1-  
and .2-M91 Natural Gas and Propane Gas Installation Codes  
(NSCNGPIC). Wear safety glasses and work gloves. Have fire  
extinguisher available during start-up and adjustment procedures  
and service calls.  
A92057  
Fig. 2—Model 394HAD Upflow  
WARNING: The ability to properly perform mainte-  
nance on this equipment requires certain expertise, me-  
chanical skills, tools, and equipment. If you do not  
possess these, do not attempt to perform any maintenance  
on this equipment other than those procedures recom-  
mended in the User’s Manual. FAILURE TO FOLLOW  
THIS WARNING COULD RESULT IN POSSIBLE  
DAMAGE TO THIS EQUIPMENT, SERIOUS PER-  
SONAL 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 word DANGER, WARNING, or CAU-  
TION. These words are used with the safety-alert symbol. DAN-  
GER identifies the most serious hazards which will result in severe  
personal injury or death. WARNING signifies a hazard that 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 sugges-  
tions that will result in enhanced installation, reliability, or  
operation.  
CARE AND MAINTENANCE  
For continuing high performance and to minimize possible equip-  
ment 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.  
—1—  
 
MOUNTING  
SCREWS  
DRAFT  
SAFEGUARD  
SWITCH  
AUXILIARY  
LIMIT SWITCH  
(NOT VISIBLE)  
FLUE  
COLLECTOR  
BOX  
RELIEF  
BOX  
SPEED  
SELECTOR  
VENT PIPE  
ENCLOSURE  
GAS  
VALVE  
MOUNTING  
SCREWS  
CONTROL  
BOX  
PILOT  
DRAFT  
SAFEGUARD  
SWITCH  
CONTROL  
BOX  
RELIEF  
BOX  
SPEED  
SELECTOR  
FLUE  
COLLECTOR  
BOX  
FILTER  
RETAINER  
WASHABLE  
FILTER  
A92178  
A92179  
Fig. 4—Model 394HAD Upflow  
b. Remove blower and control access doors.  
Fig. 5—Model 396HAD Downflow  
3. Disconnect wires from auxiliary limit on blower housing  
(downflow furnace only).  
c. Release filter retainer from clip at front of furnace  
casing. (See Fig. 4.) For side return, clips may be used on  
either or both sides of the furnace.  
4. Remove control box.  
5. Remove electrical leads from numbered side of blower  
speed selector. (See Fig. 4 and 5.) Note location of wires for  
reassembly.  
d. Slide filter out.  
e. Furnaces are equipped with permanent, washable filters.  
Clean filters with tap water. Spray water through filter in  
opposite direction of airflow.  
6. Remove screws holding blower assembly to blower deck  
and slide blower assembly out of furnace.  
f. Rinse and let dry. Oiling or coating of filter is not  
recommended or required.  
7. Squeeze side tabs of blower speed selector and pull it out of  
blower housing.  
g. Reinstall filter.  
8. Loosen screw in strap holding motor capacitor to blower  
housing and slide capacitor out from under strap.  
h. Replace access doors.  
i. Restore electrical power to furnace.  
9. Mark blower wheel, motor, and motor support in relation to  
blower housing before disassembly to ensure proper reas-  
sembly.  
B. Blower Motor and Wheel  
For long life, economy, and high efficiency, clean accumulated dirt  
and grease from the blower wheel and motor annually.  
10. Loosen setscrew holding blower wheel on motor shaft.  
11. 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.  
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 switch in AUTO position), or every 2  
years if motor is in continuous operation (thermostat FAN switch  
in ON position).  
12. Lubricate motor (when oil ports are provided).  
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.  
Remember to disconnect the electrical supply before removing  
access doors.  
c. Allow time for total quantity of oil to be absorbed by  
each bearing.  
Clean and lubricate as follows:  
d. Wipe excess oil from motor housing.  
e. Replace dust caps or plugs on oil ports.  
1. Remove 2 screws from blower access door (downflow  
furnace only). Remove blower access door.  
13. Remove blower wheel from housing.  
2. Remove vent pipe enclosure (downflow furnace only) and  
disconnect short piece of vent pipe from relief box.  
a. Mark cutoff location to ensure proper reassembly.  
—3—  
 
b. Remove screws holding cutoff plate and remove cutoff  
plate from housing.  
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).  
c. Lift blower wheel from housing through opening.  
14. 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.  
(2.) Use 1/4-in. diameter wire brush (commonly known  
as 25-caliber rifle cleaning brush).  
NOTE: The items needed in steps (1.) and (2.) can usually be  
purchased at local hardware stores.  
15. Reinstall blower wheel by reversing steps 13 a. through c.  
Be sure wheel is positioned for proper rotation.  
(3.) Insert twisted wire end of brush into end of steel  
spring cable, and crimp tight with crimping tool or  
strike with ball-peen hammer. TIGHTNESS is very  
important.  
16. Reassemble motor and blower by reversing steps 5 through  
11. If motor has ground wire, be sure it is connected as  
before.  
(4.) Remove metal screw fitting from wire brush to  
allow insertion into cable.  
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.  
b. Clean each heat exchanger cell.  
(1.) Attach variable-speed, reversible drill to end of  
steel spring cable (end opposite brush).  
(2.) Insert brush end of cable into upper opening of cell  
and slowly rotate with drill. DO NOT force cable.  
Gradually insert at least 36 in. of cable into 2 upper  
passes of cell. (See Fig. 6.)  
17. Reinstall blower assembly in furnace. Connect electrical  
leads to blower speed selector. Please note that connections  
are polarized for assembly. DO NOT FORCE.  
18. Reinstall control box.  
19. Reconnect wires to auxiliary limit switch on blower housing  
(downflow furnaces only).  
20. Reinstall vent pipe and enclosure (downflow furnaces  
only).  
21. Turn on electrical power and check for proper rotation and  
speed changes between heating and cooling.  
22. Replace blower access door and secure with 2 screws  
(downflow furnace only).  
C. Cleaning Heat Exchanger  
The following steps should be performed by a qualified service  
technician:  
A91252  
Fig. 6—Cleaning Heat Exchanger Cell  
NOTE: Deposits of soot and carbon indicate the existence of a  
problem which needs to be corrected. Take action to correct the  
problem.  
(3.) Work cable in and out of cell 3 or 4 times to obtain  
sufficient cleaning. DO NOT pull cable with great  
force. Reverse drill and gradually work cable out.  
If it becomes necessary to clean the heat exchanger because of  
carbon deposits, soot, etc., proceed as follows:  
(4.) Remove burner assembly and cell inlet plates.  
1. Turn off gas and electrical power to furnace.  
(5.) Replace screws in center panel and cells before  
cleaning.  
2. Remove 2 screws from blower access door (downflow  
furnace only). Remove control and blower access doors.  
(6.) Insert brush end of cable in lower opening of cell,  
and proceed to clean 2 lower passes of cell in same  
manner as 2 upper passes.  
3. Remove vent pipe enclosure (downflow furnace only) and  
disconnect vent pipe from relief box.  
4. Remove 2 screws that secure relief box. (See Fig. 4 or 5.)  
(7.) Repeat foregoing procedures until each cell in  
furnace has been cleaned.  
5. Disconnect wires to the following components:  
a. Draft safeguard switch  
(8.) Remove residue from each cell using vacuum  
cleaner.  
b. Inducer motor  
(9.) Clean burner assembly using vacuum cleaner with  
soft brush attachment.  
c. Pressure switch  
d. Limit overtemperature switch  
e. Gas valve  
(10.) Reinstall cell inlet plates and burner assembly.  
Care must be exercised to center the burners in the  
cell openings.  
f. Edge connector leading to control box  
6. Remove 8 screws that secure flue collector box to center  
panel. Be careful not to damage sealant.  
9. After cleaning flue openings, check sealant on flue collector  
to ensure that it has not been damaged. If new sealant is  
needed, contact your dealer or distributor.  
7. Remove complete inducer assembly from furnace, exposing  
flue openings.  
10. Clean and replace flue collector assembly, making sure all  
8 screws are secure.  
8. Clean cells using field-provided small wire brush, steel  
spring cable, reversible electric drill, and vacuum cleaner.  
11. Reinstall 2 screws in relief box.  
—4—  
 
12. Reconnect wires to the following components:  
a. Draft safeguard switch  
PILOT HEAD V–NOTCH FALLS  
DIRECTLY BELOW FRONT EDGE  
OF BURNER CARRYOVER.  
b. Inducer motor  
c. Pressure switch  
d. Limit overtemperature switch  
e. Gas valve  
f. Edge connector leading to control box  
1
/  
8
13. Reconnect vent pipe to relief box. Replace vent pipe  
enclosure (downflow furnace only).  
14. Replace blower access door only and secure with 2 screws  
(downflow furnace only).  
15. Turn on electrical power and gas.  
16. Set thermostat and check furnace for proper operation.  
A91249  
WARNING: Never use a match or other open flame to  
check for gas leaks. Use a soap-and-water solution. A  
failure to follow this warning could result in fire, personal  
injury, or death.  
Fig. 7—Position of Pilot to Burner  
E. Pilot  
Check the pilot and clean if necessary at the beginning of each  
heating season. The pilot flame should be high enough for proper  
impingement of the flame sensing element (or thermocouple) and  
to light the burners. Remove the accumulation of soot and carbon  
from the flame sensing element (or thermocouple). Refer to Fig. 7  
for proper location of pilot on burner assembly.  
17. Check for gas leaks.  
18. Replace control access door.  
D. Electrical Controls and Wiring  
NOTE: There may be more than 1 electrical supply to unit.  
The electrical ground for 115-v wiring must be maintained  
properly. Refer to Fig. 8 for field wiring information and to Fig. 9  
for unit wiring information.  
F. Troubleshooting  
With power disconnected to unit, check all electrical connections  
for tightness. Tighten all screws on electrical connections. If any  
smoky or burned connections are noticed, disassemble the connec-  
tion, clean all parts and stripped wire, and reassemble properly and  
securely. Electrical controls are difficult to check without proper  
instrumentation; therefore, reconnect electrical power to unit and  
observe unit through 1 complete operating cycle.  
The 24-v circuit contains an automotive-type, 3-amp fuse located  
on the main control board. Any direct shorts during installation,  
service, or maintenance could cause this fuse to blow. If fuse  
replacement is required, use ONLY a 3-amp fuse of identical size.  
Page 8 contains a troubleshooting chart. This chart can be a useful  
tool in isolating furnace operation problems. Beginning with the  
word "Start," answer each question and follow the appropriate  
arrow to the next item.  
The chart will help identify the problem or failed component. After  
replacing any component, verify correct operating sequence as  
indicated by bold arrows.  
—5—  
 
FIELD 24-VOLT WIRING  
FIELD 115-, 208/230-, 460-VOLT WIRING  
FACTORY 24-VOLT WIRING  
FACTORY 115-VOLT WIRING  
THERMOSTAT  
TERMINALS  
W
R
G
Y
FOUR  
WIRE  
FIELD-SUPPLIED  
FUSED DISCONNECT  
TWO-WIRE  
HEATING-  
ONLY  
208/230- OR  
460-VOLT  
THREE  
PHASE  
W
R
BLK  
BLK  
WHT  
WHT  
208/230-  
VOLT  
SINGLE  
PHASE  
GND  
GND  
G
AUXILIARY  
J-BOX  
115-VOLT FIELD-  
SUPPLIED  
FUSED  
DISCONNECT  
C
Y
GND  
CONTROL  
CONDENSING  
UNIT  
BOX  
TWO  
24-VOLT  
NOTE: If any of the original wire,  
as supplied, must be replaced, use  
same type or equivalent wire.  
WIRE  
TERMINAL  
BLOCK  
NOTE: Connect Y-terminal as  
shown for proper  
FURNACE  
operation.  
A78461  
Fig. 8—Heating and Cooling Application Wiring Diagram  
—6—  
 
Y E L  
O R N  
B R N  
B L U  
R E D  
R E D  
W H T  
B L K  
R E D  
B L U  
B L K  
B L K  
W H T  
R E D  
W H T  
—7—  
 
START  
Turn on 115-VAC  
power to unit.  
Disconnect all thermostat  
wires from board.  
Turn off 115-VAC  
power to unit.  
NO  
Are  
Is 24VAC  
across screws  
W & C or  
all thermostat  
wires to board  
disconnected?  
Is 24VAC  
across screws  
R & C?  
YES  
YES  
YES  
Is blower  
running?  
G & C?  
NO  
NO  
NO  
YES  
Check/Replace:  
1. Limit switch  
Jumper across  
screws R & G.  
Replace  
board.  
2. Limit shield (if used)  
3. Fuse link  
4. Auxillary limit switch (if used)  
5. Wire harness  
YES  
Is  
Is  
Is  
Is  
YES  
NO  
NO  
24VAC  
115VAC  
across HI &  
COM?  
115VAC  
across L1 &  
L2?  
blower running  
on cooling  
speed?  
across screws  
R & C?  
YES  
YES  
NO  
NO  
Replace  
blower motor  
and/or start  
capacitor.  
Check/Replace:  
1. Unit power  
2. Door switch  
3. Power harness  
Check/Replace:  
1. 3-amp board  
fuse  
Is  
NO  
115VAC  
Replace  
board.  
across EAC-1  
& COM?  
2. Transformer  
Check pressure  
tube for leak or  
YES  
Is  
24VAC  
NO  
crimp; otherwise,  
Replace  
board.  
Remove  
R & G jumper.  
across PL1-2  
& screw C on  
board?  
replace pressure switch  
NO  
YES  
YES  
Is heat  
exchanger  
pressure drop greater  
than 0.35-in.  
wc?  
Is 24VAC  
across pressure  
switch N/O contact  
& screw C on  
board?  
Repair wire  
harness.  
Does  
blower turn  
off?  
YES  
NO  
NO  
NO  
YES  
Check/Replace:  
1. Vent systems  
2. Induce wheel  
Is 24VAC  
across pressure  
switch N/O contact  
& screw C on  
board?  
YES  
Check/Replace:  
1. Draft safeguard switch  
2. Wire harness  
Jumper across  
screws R & W.  
3. Flue choke  
4. Inducer voltage  
5. Inducer motor bearings  
NO  
Check/Replace:  
1. Pilot  
Is  
inducer motor  
on?  
YES  
Is  
YES  
YES  
NO  
Is  
24VAC across gas  
valve?  
unit lit?  
2. Thermocouple  
3. Gas valve  
NO  
YES  
Is  
Is  
Is  
Replace  
blower motor  
and/or start  
capacitor.  
blower running  
on heat speed 45  
sec after unit  
lights?  
YES  
NO  
115VAC across  
inducer motor  
connector?  
115VAC across  
inducer motor  
connector?  
Replace  
inducer motor.  
NO  
NO  
YES  
Is  
Is  
Is  
24VAC  
YES  
NO  
24VAC across  
PL-2 & screw  
C on board?  
115VAC  
across EAC-1  
& COM?  
NO  
across  
PL-1 & screw  
C on board?  
Replace  
board.  
Check/Repair  
wire harness;  
otherwise,  
replace  
NO  
YES  
YES  
Check/Replace  
thermostat  
Replace  
board.  
Remove  
R & M jumper.  
Repair wire  
harness.  
and/or  
pressure  
thermostat wiring.  
switch.  
NO  
After  
NO  
YES  
off-delay  
does blower  
turn off?  
Reconnect all  
thermostat wires.  
Does unit  
operate?  
NOTE: After replacing any component, verify correct operating  
YES  
sequence as indicated by bold arrows.  
END OF TEST.  
A91253  
© 1993 BDP Co. • P.O. Box 70 • Indianapolis, IN 46206  
Printed in U.S.A.  
35001b  
Catalog No. BDP-3339-432  
—8—  
 

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