John Wood Envirosense Power Direct Vent (prior to May 2010) - Manual (Page 30)

30
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.
Table 3 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.
taBle 3.
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
valve 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.
teMperature reGulatIon
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.
time to produce
2nd & 3rd degree
temperature setting Burns on adult skin