Temperature Regulation; High Temperature Limit Control (Eco); Thermostat Control; Firing Rate Modulation - State Water Heaters 301 Series Instruction Manual

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 (page 9) and
Figure 4
for location. The ECO switch contacts will open when the water
temperature reaches approximately 202°F (94°C) and close at
approximately 140°F (60°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:
If the ECO activates, the water temperature must drop below
140°F (60°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 17
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 or at the hot water taps to further
reduce system water temperature. See
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

(page 10)
Figure 5
(page 44) shows the approximate
(page 14).
Figure 7
Table 17. Time/Temperature to Burn
Water Temperature Time for 1st Degree Burn
°F (°C) (Less Severe Burns)
110 (43) (normal shower temp.)
116 (47) (pain threshold)
116 (47) 35 minutes
122 (50)
131 (55) 5 seconds
140 (60) 2 seconds
149 (65)
instantaneous
154 (68)
(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
(page 8) and
Figure 3
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
The Operating Set Point is adjustable from 90°F (32°C) to 180°F
(82°C). The factory setting is 120°F (49°C). See
and Differential Adjustment
adjust the Operating Set Point and other user settings.
Set the Operating Set Point at the lowest setting that produces
an acceptable hot water supply. This will always provide the most
energy efficient operation.

FIRING RATE MODULATION

The water heaters covered by this manual are capable of
modulating their firing rate. The central control board (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.

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
Operating Set Point
Status: Heating
MENU
Figure 57. Tank Temperature Set point
44
Time for Permanent
Burns
2nd & 3rd Degree
(Most Severe Burns)
45 minutes
1 minute 5 minutes
25 seconds
5 seconds
1 second 2 seconds
1 second
(page 9) for location.
Figure 4
(page 44).
Figure 57
Operating Set Point
(page 48) for instructions on how to
103°F
120°F
OFF
O
GAS
N
HELP