Kenmore HydroSense 153.33443, Owner'S Manual

23

Start Up Conditions                

Thermal Expansion

Water supply system may, because of such events as high line 
pressure, frequent cut-offs, and the effects of water hammer have 
installed devices such as pressure reducing valves, check valves, 
back fl ow preventers, etc., to control these types of problems.  
When these devices are not equipped with an internal by-pass, 
and no other measures are taken, the devices cause the water 
system to be closed.  As water is heated, it expands (thermal 
expansion) and closed systems do not allow for the expansion 
of heated water.

The water within the water heater tank expands as it is heated and 
increases the pressure of the water system.  If the relieving point 
of water heater’s temperature-pressure relief valve is reached, 
the valve will relief the excess pressure.  

The temperature-

pressure relief valve is not intended for the constant relief 
of thermal expansion.

  This is an unacceptable condition and 

must be corrected.

It is recommended that any devices installed which could 
create a closed system have a by-pass and/or the system have 
an expansion tank or device to relieve the pressure built by 
thermal expansion.   Thermal expansion tanks are available from 
Sears stores and through the Sears Service Centers.  Contact 
the local plumbing inspector, water supplier and/or the Sears 
Service Center for assistance in controlling these situations.  
See Figure 26.

Thermal Expansion Tank Specifi cations

 Tank 

                 Dimensions   

Pipe

 Model 

  Capacity                  in Inches 

 Fitting

 Number  In 

Gallons  Diameter 

Length 

On 

Tank

  153.331020 

2 

8 (203 mm)  12-3/4 (323 mm)   3/4” Male

  153.331050 

5 

11 (279 mm)  14-3/4 (375 mm)   3/4” Male

Expansion Tank Sizing Chart

Inlet*        Water Heater Capacity (Gallons)

Water

Pressure 30  40 50 66 80

Expansion

 40psi  2  2 2 5 5

Tank

50psi  2  2 2 5 5

Capacity

 60psi 2 2 5 5 

5

Needed

 70psi 2 2 

5 

5 

5

80psi  2  5 5 5 5

*Highest recorded inlet water pressure in a 24 hour period or 
regulated water pressure.

NOTE: Expansion tanks are pre-charged with a 40 psi air 
charge.  If the inlet water pressure is higher than 40 psi, the 
expansion tank’s air pressure must be adjusted to match 
that pressure, but must not be higher than 80 psi.

FIGURE 26.

Strange Sounds

Possible noises due to expansion and contraction of some metal 
parts during periods of heat-up and cool-down do not represent 
harmful or dangerous conditions.

Condensation causes sizzling and popping within the burner area 
during heating and cooling periods and should be considered 
normal.  See 

Condensation

 section.

Draft Hood Operation

Check draft hood operation by performing a worst case 
depressurization of the building. With all doors and windows 
closed, and with all air handling equipment and exhaust fans 
operating such as furnaces, clothes dryers, range hoods and 
bathroom fans, a match fl ame should still be drawn into the draft 
hood of the water heater with its burner fi ring. If the fl ame is not 
drawn toward the draft hood, shut off water heater and make 
necessary air supply changes to correct.