A.O. Smith Dve-52/80/120 Flushing, Sediment Removal, Lime Scale Removal, Maintenance Schedule

its diameter is 3/8” (1 cm) of an inch, or annually which ever is first. Aggressive, very hot and softened water causes rapid consumption of the anode requiring frequent inspections. Call the toll free number on the back cover of this manual for information on obtaining replacement anode rods.

MAINTENANCE SCHEDULE

Component	Operation	Interval	Required
Tank	Flushing	Periodically
Elements	Lime Scale	As needed	Un•Lime®
	Removal		delimer &
			element
			gaskets, Part

Tank flushing should be performed in accordance with the above schedule. Tank sediment removal and element lime scale removal must be performed as needed as determined by periodic inspection. Following are the instructions for performing recommended maintenance.

FLUSHING

The water heater drain valve should be opened periodically to help prevent sediment buildup on the tank bottom.

1.Turn off the electrical disconnect switch.

2.Attach hose to outlet opening of drain valve and direct end to drain.

•Open the drain valve by turning the hand wheel to the left (counterclockwise). Allow water to flow until it runs clean.

•If water does not flow from opened drain valve, follow instructions for sediment removal.

3.When finished flushing:

•Close heater drain valve and remove hose.

•Turn on electricity.

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, the elements should be examined 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 delimer 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 dissolvents will not remove these types of scale which are 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 the 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 each element and install into tank openings.

•Uniformly tighten element bolts. Torque to approximately 32 ft./lbs.

5.Attach element wires to connection points from which they were removed.

6.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.

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