A.O. Smith BTH 120 - 250 - Manual (Page 29)

29
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 damage d. 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 also.
TROUBLE-SHOOTING
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
MICROAMMETER, 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 15 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 HEATED WIRE
TO GROUND CHECK INDICATES ZERO VOLTAGE.