Temperature Regulation; Temperature Adjustment - A.O. Smith PXHT Instruction Manual

Due to the nature of the typical water heater, the water temperature in
certain situations may vary up to 30°F (16.7 °C) higher or lower at the
point of use such as, bathtubs, showers, sink, etc.
Any water heater's intended purpose is to heat water. Hot water is
needed for cleansing, cleaning, and sanitizing (bodies, dishes, clothing).
Untempered hot water can present a scald hazard. Depending on the
time element, and the people involved (adults, children, elderly, infirm,
etc.) scalding may occur at different temperatures.
HOTTER 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 in your home 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,
shall be used at the hot water taps used by these people or at the
water heater. Mixing valves are available from your local plumbing
contractor. 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.
THIS WATER HEATER IS EQUIPPED WITH AN ADJUSTABLE
THERMOSTAT TO CONTROL WATER TEMPERATURE. HOT
WATER TEMPERATURES DESIRED FOR AUTOMATIC
DISHWASHER AND LAUNDRY USE CAN CAUSE SCALDS
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.
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
temperature thermostat (See Figure 3) 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. Thermostat(s) are
factory set at 120°F (49°C) unless specified differently by state
requirements.

TEMPERATURE REGULATION

KEEPING THE THERMOSTAT SETTING AT 120°F WILL REDUCE THE
RISK OF SCALDS.
Figure 7 shows the approximate time-to-burn relationship for normal
adult skin. The thermostats on your water heater have a linear
relationship between degrees of angular rotation and the corresponding
change in temperature. Thus rotating the temperature adjustment
indicator 30 angular degrees will result in a 10 degree Fahrenheit
change in water temperature.

TEMPERATURE ADJUSTMENT

To change the temperature setting:
1. Turn off the heater electrical supply. Do not attempt to adjust
thermostat with power on.
2. Remove the thermostat access panels and covers from the
thermostats. Do not remove the plastic personnel protectors covering
the thermostats.
3. Using a flat tip screwdriver, rotate the adjustment knob to the desired
temperature setting.
4. Replace the covers and access panels and turn on heater electrical
supply.
Temperature
Settings
160°F (71°C)
°C)
150°F (66
140°F (60°C)
130°F (54°C)
120°F (49°C)
80°F (27°C)
11
Time to Produce 2nd & 3rd
Degree Burns on Adult Skin
About 1/2 second
About 1-1/2 seconds
Less than 5 seconds
About 30 seconds
More than 5 minutes
- - - - - - - - - - - - - - - -
FIGURE 7.