Troubleshooting; Common Service Problems; Surface Mount Control Models - A.O. Smith dre-52 Service Handbook

TROUBLESHOOTING

COMMON SERVICE PROBLEMS

No Hot Water
1 Hot water supply valve turned off.
2 Check power to the water heater - see pages 12 - 14.
3 Check thermostat/ECO controls on Surface Mount Control Models - see pages 18 & 19.
4 Check Operating Set Point and Differential Set Points on Electronic Control Models - see pages 52 & 53.
5 Check all fuses - see page 17.
6 Check heating elements pages 20 - 26.
7 Ensure both enable/disable circuits at the CCB's J7 plug/socket connection are closed circuits on
Electronic Control Models. See CCB Enable/Disable Circuit(s) Test on page 45.
Not Enough Hot Water
1 Water heater may be undersized.
2 Check thermostat/ECO controls on Surface Mount Control Models - see pages 18 & 19.
3 Check Operating Set Point and Differential Set Points on Electronic Control Models - see pages 52 & 53.
4 On Electronic Control Models ensure the water heater is not in the Economy Mode during peak demand
periods and ensure the time is set correctly (daylight savings etc) - see pages 55 - 58.
5 Ensure the power supply matches the listed voltage on the water heater rating plate - see pages 12 - 14.
6 Check for water supply piping leak or restriction: lime/scale - valve partially closed.
7 Check all fuses - see page 17.
8 Check heating elements pages 20 - 26.
9 Check Contactors on Electronic Control Models - see pages 29 - 33.
10 Check both enable/disable circuits at the CCB's J7 socket on Electronic Control Models. If either/both
circuits are being used by a supervisory control(s) check that control's settings to ensure it is not disabling
heating operation during occupied/normal demand periods. See the CCB Enable/Disable Circuit(s) Test on
page 45 and Heater Status Menu information on page 54.
Water Heater Trips Breaker
1 Ensure the power supply breaker/fusing to the water heater meets the minimum required fuse/wire/breaker
sizing. See the listed voltage and amperage on the water heater rating plate - see pages 12 - 14.
2 Ensure the internal power supply phase wiring is configured correctly - see pages 15 & 16.
3 Check for grounded heating elements - see page 26.
4 Check for pinched/shorted wiring - internal wiring or power supply wiring.
Contactor Chatter
Condition: contactors opening and closing rapidly.
1 Ensure the 120 VAC Control Circuit Transformer is properly configured to match the power supply to the
water heater on Electronic Control Models - see page 34.
2 Ensure the power supply to the water heater matches the listed voltage on the water heater rating plate -
see pages 12 - 14.
3 Ensure wiring connections at 120 VAC contactor coil(s) are secure and in good condition - see page 32.

SURFACE MOUNT CONTROL MODELS

See the Common Service Problems above.
TROUBLESHOOTING
Servicing should only be performed by a Qualified Service Agent
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