Sediment Removal; Lime Scale Removal - A.O. Smith 100 Series Instruction Manual

The use of a water softener may decrease the life of the water
heater tank.
The anode rod should be inspected annually.
The following are typical (but not all) signs of a depleted anode rod:
• The majority of the rods diameter is less than 3/8".
• Significant sections of the support wire (approx. 1/3 or more
of the anode rod's length) are visible.
Note: If the anode rod show signs of either or both it should be
replaced. Whether re-installing or replacing the anode
rod, check for any leaks and immediately correct if
found.
Figure 13. Anode Depletion
If the anode rod show signs of either or both it should be replaced.
Note: Whether re-installing or replacing the anode rod, check
for any leaks and immediately correct if found.
To replace the anode:
1. Turn off electric supply to the water heater.
2. Shut off the water supply and open a nearby hot water faucet to
depressurize the water tank.
3. Drain approximately 5 gallons of water from tank. (Refer to
"Draining and Flushing" for proper procedures). Close drain valve.
4. Remove old anode rod.
5. Use Teflon® tape or approved pipe sealant on threads and install
new anode rod.
6. Turn on water supply and open a nearby hot water faucet to purge
air from water system. Check for any leaks and immediately
correct any if found.
7. Restart the water heater as directed in this manual.
CAUTION
Property Damage Hazard
To avoid water heater damage, fill tank with water
before operating.
• Burn hazard.
• Hot water discharge.
• Keep hands clear of drain
valve discharge.

SEDIMENT REMOVAL

Water borne impurities consist of fine particles of soil and sand which
settle out and form a layer of sediment on the bottom of the tank. In
time, if not removed, the level of sediment might reach the heating
elements and cause their failure.
For convenience, sediment removal and element lime scale removal
should be performed at the same time as follows.

LIME SCALE REMOVAL

Lime scale accumulations on the heating elements is a normal
condition, common to all immersion type elements. Factors which
affect the amounts of this formation are:
1. Amount of hot water used. As the volume of water heated
increases, more scale results.
2. Water temperature. As the temperature of the water is increased,
more scale is deposited on the elements.
3. Characteristics of water supply.
Regardless of water treatment, examine elements regularly.
Lime scale accumulations may cause noises to occur during
operation.
It is recommended that a heating element be removed periodically
for examination. If it is scaled, all of the elements should be removed
and cleaned. If the tank bottom has an accumulation of sediment it
should be cleaned.
Lime scale should be removed by dissolving the accumulation in
UN•LIME® delimer. Do not use muriatic or hydrochloric acid base
deliming solutions to remove lime scale from the elements.
THE PROCESS FOR LIME SCALE REMOVAL IS AS FOLLOWS:
1. Turn off electrical disconnect switch.
2. Drain the heater following DRAINING instructions.
3. Open front panel.
4. Disconnect the element wiring. Try not to disturb the wiring
unnecessarily and reconnection will be easier.
5. Unscrew each element.
6. Remove the elements and gaskets from the openings.
• Use a twisting, pulling action to remove elements scaled
beyond the size of the tank openings.
• Brush loose scale from elements.
7. Lime scale removal:
• Place limed ends of heating elements into UN•LIME de-
limer and allow scale to dissolve. Do not permit delimer
or water to contact heating element electrical terminals.
• Silicates, sulfates and aluminates must be removed by
scraping or other mechanical means. Lime scale dissol-
vents willnot remove these types of scale occasionally
encountered.
Call the toll free phone number on the back cover of this Instruction
Manual to purchase UN-LIME and heating element gaskets.
OTHER SCALE REMOVAL:
1. Flush cleaned ends of elements with water when deliming or
cleaning is completed.
2. Remove sediment and scale from the tank bottom through access
provided by the element openings or drain valve opening.
• The cold water inlet valve and drain valve may be opened
to aid the cleanout process.
3. Clean remaining gasket material from tank and element flanges
Do not reuse original element gaskets.
4. Put new gaskets on elements and install into tank openings.
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