Unit installation

33
To clean heater through cleanout opening, proceed as follows:
1. Disconnect electrical cover and drain heater.
2. Remove outer cover plate from lower side of heater jacket.
3. Remove six (6) hex head screws securing tank cleanout plate
and remove plate.
4. Remove lime, scale, or sediment using care not to damage the
glass lining.
5. Inspect cleanout plate gasket: if new gasket is required, replace
with A. O. Smith Part No. 99038.
6. Install cleanout plate. Be sure to draw plate up tight by
tightening screws securely.
7. Replace outer jacket cover plate.
In some water areas the sediment might not be removed by this
method and may result in the water heater making rumbling or
boiling noises. To dissolve and remove these more stubborn
mineral deposits, A. O. Smith UN•LIME Professional Delimer
should be used (except in Canada).
Flo-Jug Method of Deliming
The Flo-Jug is the standard 5 gallon (18.9 L) container for UN•LIME
-or- it is available as a deliming kit with hose and fittings. Contact
your dealer, distributor or the A. O. Smith Product Service Division.
Figure 24 illustrates most of the following steps.
1. The heater should be prepared for deliming as described in
the “Why? When and How” booklet. The relief valve may also
be delimed at this time.
2. With the Flo-Jug upright:
• Take off cap, remove cover under opening and install 3/4" x
4" pipe nipple.
• Drill or punch a 3/16" vent hole in handle. A stainless steel
screw is included with the Flo-Jug kit. This screw is to be
installed in the vent hole when Flo-Jug is not in use.
• Remove drain valve from heater and insert a 3/4" x 4"
nipple.
• Connect and clamp 1" I.D. x 3' hose to Flo-Jug and heater
nipple.
3. Lift the Flo-Jug to the pour position and permit the UN• LIME
to flow into the heater as rapidly as possible.
•Be sure to keep the vent just above the liquid level.
4. Place the Flo-Jug in the DELIME POSITION.
• It may be necessary to place this empty jug on its carton to
trap the solution in the heater.
• Allow the UN•LIME to attack the water scale for 5 minutes.
5. Lower the Flo-Jug to the DRAIN POSITION and allow the
UN•LIME to flow out of the heater as rapidly as possible.
• Observe the vent hole and elevate the jug slightly if there is
a possibility of spillage.
• Deliming activity is indicated by foaming on the surface of
the solution.
6. Continue the deliming process:
• Raise jug to POUR POSITION. Allow solution to flow into
heater.
• Place jug in DELIME POSITION for 5 minutes. Solution is at
work in heater.
• Lower jug to DRAIN POSITION and allow solution to flow
out. Observe foaming.
FIGURE 24
7. After one hour, or earlier if the deliming activity (foaming)
stops, inspect the tank interior.
• Drain the UN•LIME back into jug, DRAIN POSITION, and
then stand jug in DELIME POSITION.
• Remove clamp, hose and pipe nipple from heater drain
opening.
• Observe interior through opening - a small flashlight may
be used effectively.
• If the interior still shows water scale, the deliming process
should be continued.
• To check UN•LIME for continued use or reuse, place some
lime scale or white chalk into a glass with a small amount of
the solution. If the material is vigorously dissolved by the
solution, the UN•LIME can be reused. If not, the UN•LIME
has been weakened and should be replaced.
8. When deliming has been completed, the heater should be
flushed for 3 to 5 minutes with fresh water.
• Remove the deliming equipment, install the drain valve,
open the cold water inlet line and allow water to flow through
heater and out drain valve. Don’t forget to plug vent and
cap opening in Flo-Jug.
9. When flushing is completed:
• Fill heater being certain to expel air from tank through a
nearby hot water faucet or, if removed, the relief valve
opening.
• Replace relief valve if removed for deliming.
• The heater relief valve can be washed in UN•LIME if it is
limed.
• Restore gas, oil or electrical supply to heater.
• Check for water leakage.
10. Flo-Jug Cleanup:
• Allow scale to separate from UN•LIME and settle on bottom
of Flo-Jug.
• Pour off UN•LIME into plastic container and check for reuse.
• Rinse sediment from Flo-Jug.