A.O. Smith HWG-140, Instruction Manual

12

MaIntenance

Note: See AttAched veNdor INFormAtIoN For mAINteNANce oF compoNeNtS.

General

Once a month the temperature/pressure relief valve should be checked 

to ensure that it is in operating condition. Lift the lever at the top of the 

valve several times until the valve seats properly and operates freely.

For  your  safety,  water  heater  service  should  be  performed  by  a 

qualified  service  technician.  Read  the  general  safety  information 

section first.

Hot  water  generator  maintenance  includes  periodic  tank  flushing 

and cleaning, and removal of lime scale from the heating elements. 

If required by pump manufacturer, water heating system circulating 

pumps should be oiled.

summary of Maintenance schedule

component

operation

Interval

required

Tank

Flushing

Monthly

Sediment 

Removal

As Needed

Heat Exchanger Tube Cleaning

Once a year

1 part muriatic 

acid to 10 parts 

water for 2 

hours

Circulating 

Pump

Water 

Lubricated

Steam Trap

Cleaning

Once a year

See Vendor 

Literature

Steam Strainer

Cleaning

taBle 3

Tank  flushing  should  be  performed  in  accordance  with  the  above 

schedule. Tank  sediment  removal  and  lime  scale  removal  must  be 

performed when needed as determined by periodic inspections.

The internal shell should be inspected for any rusting or pitting and 

corrected if possible. Maintenance of this nature will provide cleaner 

water and more efficient operation.

tank MaIntenance

In  any  water  system,  the  storage  water  heater  acts  as  a  settling 

basin for any foreign matter in the water which will deposit itself on 

the bottom of the storage section. For this reason it is recommended 

to drain the shell section down once a ear, refill it and drain it again. 

The heating coil should be inspected and cleaned of any scale or 

mineral deposits that may attach themselves to the heating surface. 

The  heating  surface  may  be  cleaned. 

refer  to  vendor’s  heat 

exchanger instruction sheet.

flushInG

1.  Valve off the heating medium (steam or hot water).

2.  Open the drain valve. Allow water to flow until it comes clean.

3.  Close the drain valve when finished flushing.

4.  Open heating medium valve.

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.

Sediment accumulation in the tank is a normal condition, common to all 

storage tanks. Factors which affect the amount 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.

Water scale accumulations may cause noises to occur during operation.

It is recommended that periodic visual checks are made. If the tank 

bottom has an accumulation of sediment, it should be cleaned.

sedIMent reMoVal

1.  Valve off the heating medium.

2.  Drain the hot water generator following DRAINING instructions.