John Wood Envirosense Power Direct Vent (May 2010 or later) - Manuel (Page 37)

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Valves for reducing the point-of-use temperature by mixing cold and
hot water are available. 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.
In all cases, the following burn table must be used. It’s appearance
may be altered to comply with each manual’s style, but the content
must remain unchanged. NOTE: If the manual is to be used outside
of the United States, metric equivalents (Celsius) must be added to
the table.
Table 11
Water Temperature
°F (°C)
Time for 1st Degree Burn
(Less Severe Burns)
Time for Permanent Burns
2nd & 3rd Degree
(Most Severe Burns)
110 (43.3) (normal shower temp.)
116 (46.7) (pain threshold)
116 (46.7) 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 (67.8) instantaneous 1 second
(U.S. Government Memorandum, C.P.S.C., Peter L. Armstrong, Sept. 15, 1978)
HI LIMIT SWITCH (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 Temperature Probe (two red wires). 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 VAC Gas Control 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 Technician 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.
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. 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.
SETTING THE WATER HEATER TEMPERATURE AT 120°F/49°C
WILL REDUCE THE RISK OF SCALDS. Some states require settings
at specific lower temperatures.
The water temperature is controlled using the Temperature Control on
the Display at the front of the unit (See “Figure 1B: 50 GALLON UNIT”
& “Figure 1C: 75 GALLON UNIT”). This control utilizes a temperature
probe to determine the tank temperature. The temperature probe is
located behind the heater’s front display.
The temperature may be adjusted from 90°F/32°C to 160°F/71°C. The
temperature was preset 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.
TEMPERATURE REGULATION