PREVENTIVE MAINTENANCE
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.
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 no. 4763 (1 gal), packed 4 gallons per case or part no. 4813 (5 gallon container).
Hydrochloric base acids are not recommended for use on glass- lined tanks.
CAUTION
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, see replacement parts list for item number.
6.Install cleanout plate. Be sure to draw plate up tight by tightening screws securely.
7.Replace outer jacket cover plate.
FIGURE 9
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.
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