Lime Scale Removal; Checklist; Replacement Parts - A.O. Smith DRE Installation And Operation Manual

Commercial electric water heaters
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12. Attach element wires to connection points from which they
were removed.
13. Follow FILLING instructions to restore hot water service.
Check for water leaks around elements and proper operation
when heater is filled.
Close the front panel.

CHECKLIST

Before calling for service, check the following points to see if the
cause of trouble can be identified and corrected.
Reviewing this checklist may eliminate the need of a service call
and quickly restore hot water service. The illustration on page 2
identifies the location of all of the heater components.
BE SURE TO TURN OFF THE ELECTRICITY WHEN CHECKING
EQUIPMENT.
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.
The heater has fusing.
3. If the water was excessively hot, and is now cold, the high
limit switch may have operated.
To reset, open the front panel and push the reset button.
Repeated operation of the high temperature cutoff should be
investigated by your dealer.
4. 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.
5. Cooler incoming water temperature will lengthen the time
required to heat water to the desired temperature.
6. Look for hot water leakage.
7. Sediment or pipe scale may be affecting water heater
operation. Refer to page 23 for details.
Water is too hot
1. Sediment or lime scale accumulations on the elements
causes sizzling and hissing noises when the heater is
operating.
The sounds are normal, however, the tank bottom and
elements should be cleaned. Refer to page 23 for
details.
2. Some of the electrical components of the water heater make
sounds which are normal.
Contactors will "click" or snap as the heater starts and stops.
Transformers and contacts often hum.
Water leakage is suspected
Refer to Leakage Checkpoint of following page.
1. Check to see if the heater drain valve is tightly closed.
2. If the outlet of the relief valve is leaking it may represent:
Excessive water temperature.
Faulty relief valve.
Excessive water pressure.
3. Excessive water pressure is the most common cause of relief
valve leakage. It is often caused by a "closed system." A check
valve in the inlet system will not permit the expanded hot water
volume to equalize pressure with the main. A relief valve must
release this water or the water heater or plumbing system will
be damaged.
When such a condition is encountered, local codes or inspection
agency should be consulted to determine which system is
acceptable in your area. These may consist of:
Installation of a second relief valve set lower than the primary
safety relief valve.
An expansion tank of suitable pressure and provision to avoid
water logging.
Removal of the check valve.
4. Examine the area around the element for gasket leakage.
Tighten the elements or, if necessary, follow the WATER AND
LIME SCALE REMOVAL procedure to replace the
gaskets.
IF YOU CANNOT IDENTIFY OR CORRECT THE
SOURCE OF MALFUNCTION
1. Place the water heater electrical switch in the OFF position.
2. Close the supply water inlet valve to the heater.
3. Contact your dealer.

REPLACEMENT PARTS

Replacement parts may be ordered through dealers, authorized
servicers, or distributors. Refer to Yellow Pages for where to call
or contact the Product Service Division, A.O. Smith Water Heater
Parts Fulfillment,125 Southeast Parkway, Franklin, TN 37068, 1-
800-433-2545. When ordering parts, specify complete model no.,
serial no., (see rating plate), quantity and name of part desired.
Standard hardware items should be purchased locally.
24

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