A.O. Smith BTH 300A - Manual (Page 32)

32
CHECKLIST AND SERVICE INFORMATION
IMPORTANT
The installer may be able to observe and correct certain problems
which might arise when the unit is put into operation or when it is
re-fired after a prolonged shutdown. HOWEVER, it is recommended
that only qualified servicemen, using appropriate test equipment,
be allowed to service the heater.
BE SURE TO TURN OFF THE ELECTRICITY WHENEVER
POSSIBLE OR APPROPRIATE WHILE CHECKING EQUIPMENT.
WARNING
FAILURE TO FOLLOW THESE INSTRUCTIONS CAN RESULT
IN SERIOUS PERSONAL INJURY OR DEATH.
CAUTION:
LABEL ALL WIRES PRIOR TO DISCONNECTION WHEN
SERVICING CONTROLS. WIRING ERRORS CAN CAUSE
IMPROPER AND DANGEROUS OPERATION.
VERIFY PROPER OPERATION AFTER SERVICING.
BURNER OPERATIONAL PROBLEMS
1. Refer to TROUBLESHOOTING.
NOT ENOUGH OR NO HOT WATER
1. Be certain the electrical disconnect switch serving the water
heater is in the ON position.
2. Check the fuses.
• The electrical disconnect switch usually contains fuses.
3. The capacity of the heater may have been exceeded by a large
demand for hot water.
• Large demands require a recovery period to restore water
temperature.
4. Colder incoming water temperature will lengthen the time
required to heat water to the desired temperature.
• If the heater was installed when incoming water temperature
was warm, colder water creates the effect of less hot water.
5. Look for hot water wastage and leaking or open hot water
faucets.
6. Sediment or lime scale may be affecting water heater operation.
Refer to MAINTENANCE for details.
7. The heater’s temperature high limit sensor has activated. Press
the reset button on the thermostat.
8. Burner may not be firing at proper rate.
• Check gas pressure. Adjust to obtain required manifold
pressure.
9. Burner fan wheel may be dirty.
• Clean fan wheel with a stiff brush.
10. Condensate hose may be blocked where it connects to the
exhaust elbow.
• Verify the condensate drains from the unit without restriction.
WATER IS TOO HOT
1. Refer to WATER TEMPERATURE CONTROL.
WATER HEATER MAKES SOUNDS
1. Sediment or lime scale accumulations cause rumbling and
pounding noises when the heater is operating.
• The sounds are normal, however, the tank bottom should
be cleaned. Refer to MAINTENANCE for details.
2. Some of the electrical components of the water heater make
sounds which are normal.
• Contacts click or snap as the heater starts and stops.
• Transformers often hum.
WATER LEAKAGE IS SUSPECTED
1. Check to see if the water heater drain valve is tightly closed.
Also check the cleanout opening for leakage.
2. The apparent leakage may be condensation which forms on
cool surfaces of the heater and piping.
3. If the outlet of the relief valve is leaking it may represent:
• Excessive water pressure.
• Excessive water temperature.
• Faulty relief valve.
Excessive water pressure is the most common cause of relief valve
leakage. It is often caused by a “closed system”. If a check valve is
in the inlet system it will not permit the expanded hot water volume
to equalize pressure with the main. The relief valve must release
this water or the water heater or plumbing system will be damaged.
Refer to MAINTENANCE-RELIEF VALVE section in this manual.
When such a condition is encountered, local codes or inspection
agency should be consulted to determine which system is
acceptable in your area. See CLOSED SYSTEM section in this manual.
TROUBLE-SHOOTING
1. Verify that the allowable vent length has not been exceeded
and that the blower inlet screen has been removed if direct
venting.
2. Verify that the condensation, which WILL be present in the
heater and exhaust vent, will drain.
3. Check supply wire polarity - hot to hot and neutral to neutral
and no "stray" current in neutral.
4. Heater is properly grounded.
Checking these four (4) items first will often result in a timely solution
to the service call.
WARNING
JUMPING OUT COMPONENTS AND/OR CIRCUITS DURING
TROUBLESHOOTING CAN CAUSE SERIOUS PROBLEMS WITH
THE UNIT’S OPERATING SEQUENCE AND IGNITION SAFETY.
IF YOU DO NOT HAVE THE PROPER TEST EQUIPMENT, I.E. A
VOLT-OHM METER AND A MICROMETER, DO NOT ATTEMPT
TO TROUBLESHOOT OR REPAIR A.O. SMITH EQUIPMENT.
ALTERING THE CONTROLLER AND/OR CONTROLLER WIRING
IN ANY WAY COULD RESULT IN INTERNAL DAMAGE TO THE
MODULE CIRCUITS, POSSIBLY ALTERING THE IGNITION
SEQUENCE ALLOWING GAS VALVES TO OPEN BEFORE THE
HOT SURFACE IGNITER IS UP TO IGNITION TEMPERATURE.
NOTE: ANY BYPASS OR ALTERATION OF THE UNITS
SAFETIES WILL RESULT IN VOIDING THE APPLIANCE
WARRANTY.
Before performing any troubleshooting familiarize yourself with the
particular appliance.
Refer to the SEQUENCE OF OPERATION and the connection
diagram located on page 16 before continuing.
Make sure the appliance is connected to a 120V AC power supply,
manual gas valve is in the ON position, and all electrical connections
are secure before continuing to troubleshoot this appliance.
CAUTION
THE WATER HEATER IS POLARITY SENSITIVE. BEFORE
APPLYING ELECTRICITY TO THIS HEATER BE CERTAIN THAT
SUPPLY NEUTRAL WIRE TO GROUND CHECK INDICATES
ZERO VOLTAGE.