43
TABLE 13
Water Temperature
°F (°C)
Time for 1st Degree Burn
(Less Severe Burns)
Time for Permanent Burns
2nd & 3rd Degree
(Most Severe Burns)
110 (43)
(normal shower temp.)
116 (47)
(pain threshold)
116 (47)
35 minutes
45 minutes
122 (50)
1 minute
5 minutes
131 (55)
5 seconds
25 seconds
140 (60)
2 seconds
5 seconds
149 (65)
1 second
2 seconds
154 (68)
instantaneous
1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15, 1978)
The water heaters covered in this manual are equipped with an
electronic control system to regulate water temperature inside
the storage tank. The control system senses temperature from
two factory installed temperature probes, one installed in the top
of the storage tank and one installed near the bottom, See Top
Views on page 8 and Figure 4 on page 9 for location.
The “Operating Set Point” is adjusted to regulate water temperature
inside the storage tank. This is an adjustable user setting in
the control system’s “Temperatures Menu.” This and all control
system menus are accessed through the UIM (user interface
module) located on the front of the water heater, see Figure 57.
The Operating Set Point is adjustable from 90°F (42°C) to 180°F
(82°C). The factory setting is 120°F (49°C). See Operating Set
Point And Differential Adjustment on page 47 for instructions
on how to adjust the Operating Set Point and other user settings.
Set the Operating Set Point at the lowest setting which produces
an acceptable hot water supply. This will always provide the most
energy efficient operation.
MODULATION
The water heaters covered by this manual are capable of
modulating their firing rate. The CCB monitors the water
temperature in the tank and regulates the firing rate to achieve
the target temperature setpoint. The firing rate is dictated by
the hot water draw, proximity to the tank temperature setpoint,
and various other temperature limitations. Periodically, when the
heater is in modulation mode, the CCB will increase the blower
speed for a short period of time to clear out any condensation
that has accumulated in the heat exchanger then decreases
the blower speed back to the modulating firing rate required to
maintain the desired tank temperature setpoint. This ramping up
and down of the blower speed is considered normal operation of
the water heater.
HIGH TEMPERATURE APPLICATIONS
Higher operating temperatures cause more wear on all water
heaters and will decrease the life span of the water heater.
Consider installing a small booster water heater for high
temperature applications, such as commercial dishwashers, to
raise the outlet temperature from the larger primary water heater
to the desired point of use temperature.
Contact your local distributor or call the technical support phone
number listed on the back cover of this manual for further
technical assistance.
Tank Temperature
103°F
Operating Set Point
120°F
Status: Heating
MENU
HELP
UP
DN
GAS
OFF
O
N
MANUFACTURER / MODEL INFORMATION
Figure 57
HIGH TEMPERATURE LIMIT CONTROL (ECO)
This water heater is equipped with an ECO (energy cut out) non
adjustable high temperature limit switch. The ECO is a normally
closed switch that opens (activates) on a rise in temperature.
The ECO is located inside the Upper Temperature Probe (two
red wires), see pages 8 and 9 for location. The ECO switch
contacts will open when the water temperature reaches
approximately 202°F (94°C) and close at approximately
140°F (49°C).
If the ECO activates (contacts open) due to abnormally high
water temperatures in the storage tank the control system will
immediately de-energize the 24 Volt Gas Valve and end the
current heating cycle. The control system will "lock out" disabling
further heating operation. The control system will display the
"Energy Cut Out (ECO)" Fault message on the LCD screen.
It is important that a Qualified Service Agent be contacted to
determine the reason for the ECO activation before resetting the
ECO. Once the reason has been determined and corrected the
ECO can be reset as follows:
Should the ECO activate, the water temperature must drop below
140°F (49°C) before the control system can be reset. Once the
water temperature has cooled below this point the power supply
to the water heater must be turned off and on again to reset the
control system.
THERMOSTAT CONTROL
Water temperature over 125°F (52°C)
can cause severe burns instantly
resulting in severe injury or death.
Children, the elderly and the
physically or mentally disabled are at
highest risk for scald injury.
Feel water before bathing or
showering.
Temperature limiting devices such as
mixing valves must be installed
when required by codes and to
ensure safe temperatures at fixtures.
Hot water temperatures required for automatic dishwasher and
laundry use can cause scald burns resulting in serious personal
injury and/or death. Table 13 shows the approximate time-to-
burn relationship for normal adult skin.
The temperature at which injury occurs varies with the person’s
age and duration of exposure. The slower response time of
children, the elderly or disabled persons increases the hazards
to them. If anyone using hot water provided by the water heater
being installed fits into one of these groups or if there is a local
code or state law requiring a certain water temperature at the
point of use, then special precautions must be taken.
In addition to using the lowest possible temperature setting that
satisfies the demand of the application a mixing valve can be
installed at the water heater (see Figure 7 on page 14) or at
the hot water taps to further reduce system water temperature.
Never allow small children to use a hot water tap or 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 Operating Set Point at 120°F (49°C) will reduce
the risk of scalds. Some States require settings at specific
lower temperatures.
TEMPERATURE REGULATION
