Troubleshooting; Common Service Problems - A.O. Smith DSE-5 Service Handbook

TROUBLESHOOTING

COMMON SERVICE PROBLEMS

No Hot Water
1 Hot water supply valve to fixtures turned off; cold water supply valve to water heater turned off.
2 Check power to the water heater - see pages 12 - 14.
3 Check Operating Set Point and Differential Set Points - see pages 61 & 62.
4 Check all fuses - see page 15.
5 Check heating elements pages 23 - 30.
6 Ensure both enable/disable circuits at the CCB's J7 plug/socket connection are closed circuits. See CCB
Enable/Disable Circuit(s) Test on page 53 and Heater Status Menu information on page 63.
Not Enough Hot Water
1 Water heater may be undersized.
2 Check Operating Set Point and Differential Set Points - see pages 61 & 62.
3 Ensure the time is set correctly (daylight savings etc) and ensure the water heater is not in the Economy
Mode during peak demand periods - see pages 64 - 67.
4 Check power to the water heater (see pages 12 - 14) - ensure there is not a "dead leg" on water heaters
configured for three phase (3Ø) power.
5 Ensure the power supply to the water heater matches the listed voltage on the water heater rating plate -
see pages 12 - 14.
6 Check hot water supply piping for leaks or restrictions: lime/scale - valve partially closed.
7 Check all fuses - see page 15.
8 Check heating elements pages 23 - 30.
9 Check Contactors on - see pages 34 - 38.
10 Ensure both enable/disable circuits at the CCB's J7 socket are closed circuits. 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 CCB Enable/Disable Circuit(s) Test on page 53
and Heater Status Menu information on page 63.
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 Check for grounded heating elements - see page 30.
3 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 - see pages 39 & 40.
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 37.
TROUBLESHOOTING
Servicing should only be performed by a Qualified Service Agent
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