Deliming Solvents; Tank Cleanout Procedure; Deliming Using Flo-Jug Method - A.O. Smith BTR 151 Instruction Manual

Lime accumulation not only reduces the life of 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.
The depth of lime buildup should be measured periodically. Heaters
equipped with cleanouts will have about 2" of lime buildup when
the level of lime has reached the bottom of the cleanout opening. A
schedule for deliming should then be set up,based on the amount
of time it would take for a 1" buildup of lime. It is recommended that
the water heater initially be inspected after 6 months.
example 1:
Initial inspection after 6 months shows 1/2" of lime accumulation.
Therefore, the heater should be delimed once a year.
example 2:
Initial inspection after 6 months shows 2" of lime accumulation.
Therefore, the heater should be delimed every 3 months.
figure 27.

deliming solVents

un LIME is recommended 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 water heater
manufacturer. Order Part number 9005416105, 1 gallon, packed 4 gallons
per case or Part number 9005417105, 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:
3. Drain heater.
4. Remove outer cover plate from lower side of heater jacket.
5. Remove six (6) hex head screws securing tank cleanout plate
and remove plate.
6. Remove lime, scale, or sediment using care not to damage
the glass lining.
7. Inspect cleanout plate gasket, if new gasket is required,
replace with part no. 9004099215.
8. Install cleanout plate. Be sure to draw plate up tight by
tightening screws securely.
9. 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, un•LIME Professional Delimer should be used.

deliming using flo-jug method

un•LIME in the 5 gallon size is recommended for deliming of all
models. Contact your local dealer, distributor or, water heater
manufacturer.
Prepare the Water heater
To delime the water heater using the Flo-Jug method, first
prepare the heater for deliming.
Do not smoke or have open flame or sparks in vicinity of heater.
Do not mix un•LIME with other chemicals. Do not allow contact
with magnesium, aluminum or galvanized metals.
29
Explosion Hazard
Flammable hydrogen gases
may be present.
Keep all ignition sources away
from faucet when turning on
hot water.