A.O. Smith 197835-001 Manuel D’Utilisation

31

The  water  temperature  is  controlled  using  the  Temperature

Control on the Display at the front of the unit (See Figure 1).

This control utilizes a temperature probe to determine the tank

temperature. The primary temperature probe is located at the

top of the tank.

The temperature may be adjusted from 90°F/32°C to 160°F/71°C.

The thermostat was adjusted to 120°F/49°C before the heater

was shipped from the factory. It is recommended that lower water

temperature be used to avoid the risk of scalding. It is further

recommended, in all cases, that the water temperature be set

for the lowest temperature which satisfies your hot water needs.

This will also provide the most energy efficient operation of the

water heater and minimize scale formation.
Valves for reducing the point-of-use temperature by mixing cold

and  hot  water  are  available,  see  Figure  2. Also  available  are

inexpensive  devices  that  attach  to  faucets  to  limit  hot  water

temperatures. Contact a licensed plumber or the local plumbing

authority.

The table below shows the approximate time-to-burn relationship for
normal adult skin. Short repeated heating cycles caused by small
hot water uses can cause temperatures at the point of use to exceed
the thermostat setting by up to 20°F/11°C. If you experience this
type of use, you should consider using lower temperature settings
to reduce scald hazards.

 

160°F (71°C)

About 1/2 Second

150°F (65°C)

About 1 1/2 Seconds

140°F (60°C)

Less than 5 Seconds

130°F (54°C)

More than 30 Seconds

120°F (49°C)

More than 5 minutes

HI LIMIT SWITCH (E.C.O.)
The top immersion well of the dual bulb controller also contains

the  high  limit  (energy  cutoff)  sensor.  The  high  limit  switch

interrupts main burner gas flow should water temperature reach

approximately 202°F/94°C.
Should  the  high  limit  switch  activate,  the  control  system  will

automatically reset the unit once the water temperature in the

tank falls below 140°F/60°C. If the unit is manually shut down

and restarted, as long as the temperature in the tank is lower

than 160°F/71°C, the unit will reset and initiate operation.
If you experience higher than usual water temperature along with

frequent automatic resetting of the system, this is evidence of high

limit switch operation. The following are possible reasons for high

limit switch operation.
•  A malfunction in the thermostatic controls would allow the gas 

control  valve  thermostat  to  remain  open  causing  water  

temperature  to  exceed  the  thermostat  setting.  The  water 

temperature  would  continue  to  rise  until  high  limit  

switch operation.

Contact  your  dealer  or  servicer  if  continued  high  limit  switch

operation occurs.

 

It is recommended that lower water temperatures be used to avoid

the risk of scalding. It is further recommended, in all cases, that the

water temperatures be set for the lowest temperature which satisfies

your hot water needs. This will also provide the most energy efficient

operation of the water heater.

HOT WATER CAN SCALD: Water heaters are intended to produce

hot water. Water heated to a temperature which will satisfy space

heating, clothes washing, dish washing, and other sanitizing needs

can scald and permanently injure you upon contact. Some people

are more likely to be permanently injured by hot water than others.

These include the elderly, children, the infirm, or physically/mentally

handicapped. If anyone using hot water from this heater fits into

one of these groups or if there is a local code or state law requiring

a certain temperature water at the hot water tap, then you must

take special precautions. In addition to using the lowest possible

temperature setting that satisfies your hot water needs, a means

such as a mixing valve, should be used at the hot water taps used

by these people or at the water heater. Mixing valves are available

at  plumbing  supply  or  hardware  stores,  see  Figure  2.  Follow

manufacturer’s  instructions  for  installation  of  the  valves.  Before

changing the factory setting on the thermostat, read the “Temperature

Regulation” section in this manual.
Never allow small children to use a hot water tap, or to draw their own

bath water. Never leave a child or handicapped person unattended

in a bathtub or shower.
The water heater should be located in an area where the general

public does not have access. If a suitable area is not available,

a  cover  should  be  installed  over  the  thermostat  to  prevent

tampering.  The  water  temperature  setting  was  factory  set  at

the lowest temperature; THIS WATER HEATER IS EQUIPPED

WITH AN ADJUSTABLE THERMOSTAT TO CONTROL WATER 

TEMPERATURE.  HOT  WATER  TEMPERATURES  REQUIRED 

FOR AUTOMATIC  DISHWASHER AND  LAUNDRY  USE  CAN 

CAUSE SCALD BURNS RESULTING IN SERIOUS PERSONAL 

INJURY AND/OR  DEATH.  THE  TEMPERATURE AT  WHICH

INJURY OCCURS VARIES WITH THE PERSON’S AGE AND THE

TIME OF THE EXPOSURE. THE SLOWER RESPONSE TIME 

OF CHILDREN, AGED OR DISABLED PERSONS INCREASES 

THE HAZARDS TO THEM. NEVER ALLOW SMALL CHILDREN 

TO USE A HOT WATER TAP, OR TO DRAW THEIR OWN BATH 

WATER.  NEVER  LEAVE A  CHILD  OR  DISABLED  PERSON 

UNATTENDED IN A BATHTUB OR SHOWER.

THE  WATER  HEATER  SHOULD  BE  LOCATED  IN AN AREA 

WHERE THE GENERAL PUBLIC DOES NOT HAVE ACCESS TO 

SET TEMPERATURES.

SETTING THE WATER HEATER TEMPERATURE AT 120°F/49°C

WILL  REDUCE THE  RISK  OF  SCALDS.  Some  states  require

settings at specific lower temperatures.