Recommended Procedure For Periodic Removal Of Lime Deposits From Tank Type Commercial Water Heaters; Deliming Solvents; Tank Cleanout Procedures - A.O. Smith BTN 120 THRU 400/A Series Installation And Operaion Manual

RECOMMENDED PROCEDURE FOR
PERIODIC REMOVAL OF LIME DEPOSITS
FROM TANK TYPE COMMERCIAL WATER
HEATERS
The amount of calcium carbonate (lime) released from water is
in direct proportion to water temperature and usage, see chart.
The higher the water temperature or water usage, the more lime
deposits are dropped out of the water. This is the lime scale
which forms in pipes, heaters and on cooking utensils.
Lime accumulation not only reduces the life of the equipment
but also reduces efficiency of the heater and increases fuel
consumption.
The usage of water softening equipment greatly reduces the
hardness of the water. However, this equipment does not always
remove all of the hardness (lime). For this reason it is
recommended that a regular schedule for deliming be
maintained.
The time between cleaning will vary from weeks to months
depending upon water conditions and usage.
Refer to A. O. Smith booklet, Form No. 4800, entitled "Why?
When and How" for detailed description on tank inspection and
cleanout. UN•LIME ® and the booklet may be obtained through
your A. O. Smith dealer or distributor.
FIGURE 14

DELIMING SOLVENTS

A. O. Smith recommends the use of UN•LIME for deliming.
UN•LIME is a patented food grade acid which is safe to handle
and does not create the harmful fumes which are associated
with other products.
UN•LIME may be obtained from your dealer, distributor or the
A. O. Smith Product Service Division. Order Part Number 4763,
1 gallon, packed 4 gallons per case or Part Number 4813, 5
gallon container.
NOTE: Un•Lime is not available for use in Canada.
Hydrochloric base acids are not recommended for use on glass
lined tanks.
Observe handling instructions on label of product being used.
TANK CLEANOUT PROCEDURE
The following practices will ensure longer life and enable the
unit to operate at its designed efficiency:
1. Once a month the heater should be flushed. Open the drain
valve and allow two gallons of water to drain from the heater.
Inlet water valve should remain open to maintain pressure in
tank.
2. A cleanout opening is provided for periodic cleaning of the
tank. Gas must be shut off and heater drained before opening
cleanout.
To clean heater through cleanout opening, proceed as follows:
1. 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.
DELIMING USING FLO-JUG METHOD
UN•LIME in the 5 gallon size is recommended for deliming of
the BT-80 100 models. UN•LIME with the necessary hoses and
fittings to delime your heater is also available as a kit: Up-N-
Down Transfer Kit. Contact your local A.O. Smith dealer,
distributor or, A.O. Smith Water Products Company:
Telephone: (800) 433-2545
Fax: (800) 433-2515
Website: www.hotwater.com/parts
Prepare the Water Heater
To delime the water heater using the Flo-Jug method, first
prepare the heater for deliming as described in the "Why? When?
and How?" booklet, Form No. 4800. Then install the long plastic
male adapter fitting into the drain valve opening of the water
heater. Use teflon tape and hand tighten only. Do not overtighten.
Prepare the Up-N-Down Transfer Kit
The next step is the preparation on the Up-N-Down Transfer Kit,
if you have not already done so:
1. With the 5 gallon Up-N-Down container in the vertical position,
unscrew the plastic vent cap in the handle and pierce the
plastic membrane over the vent boss under the cap to allow
the container to vent.
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CAUTION