John Wood Commercial Atmospheric Vent - AJWSM - Manual (Page 5)

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• Do not cover the instruction manual. Keep it on the side of the
water heater or nearby for future reference.
• Do not allow insulation to come within 2” (5 cm) of the
burners, to prevent blockage of combustion air flow to the
burners.
• Do not allow insulation to come within 9” (23 cm) of floor, (within
2” (5 cm) of bottom cover) to prevent blockage of combustion
air flow to the burners.
• Do inspect the insulation blanket frequently to make sure it
does not sag, thereby obstructing combustion air flow.
• Do obtain new labels from John Wood for placement on the
blanket directly over the existing labels.
HIGH ALTITUDE INSTALLATIONS
WARNING
INSTALLATIONS ABOVE 2000 FEET (610 METERS) REQUIRE
DIFFERENT BURNER ORIFICES IN ACCORDANCE WITH
THE NATIONAL FUEL GAS CODE (ANSI Z223.1). FAILURE TO
UTILIZE THE PROPER ORIFICES WILL RESULT IN IMPROPER
AND INEFFICIENT OPERATION OF THE APPLIANCE
RESULTING IN THE PRODUCTION OF INCREASED LEVELS
OF CARBON MONOXIDE GAS IN EXCESS OF SAFE LIMITS
WHICH COULD RESULT IN SERIOUS PERSONAL INJURY
OR DEATH.
You should contact your gas supplier for any specific changes
which may be required in your area.
As elevation above sea level is increased, there is less
oxygen per cubic foot of air. Therefore, the heater input
rate should be reduced at high altitudes for satisfactory
operation with the reduced oxygen supply. Failure to make
this reduction would result in an overfiring of the heater
causing sooting, poor combustion and/or unsatisfactory
heater performance.
Ratings specified by manufacturers for most appliances apply for
elevations up to 2000 feet (610 m). For elevations above 2000
feet (610), ratings must be reduced at the rate of 4% for each
1000 feet (305 m) above sea level. For example, if a heater is
rated at 120,000 Btuh (35 Kwh) at sea level, to rate the heater
at 4000 feet (1219 m), you subtract 4 (once for each thousand
feet) x 04 (4% input reduction) x 120,000 (original rating) from
the original rating. Therefore, to calculate the input rating at
4,000 feet (121.9 m): 4 x .04 x 120,000 =19,200 Btuh (5.6 Kwh),
120,000 (35 Kwh) - 19,200 (5.6 Kwh) = 100,800 Btuh (29.4 Kwh).
At 6000 feet (1829 m) the correct input rating should be 91,200
Btuh (26.7 Kwh).
The input reduction is primarily achieved by reducing the
size of the main burner orifices. To do this, the main burner
orifices require replacement with orifices sized for the
particular installation elevation. Correct orifice sizing and
parts may be obtained from GSW Water Heating. When
ordering, be sure to state the model number and the altitude
of the location where the water heater is being installed.
Upon completion of derating of the heater, adjustment to the
gas pressure regulator may be required. See CHECKING
THE INPUT section in this manual for inlet and manifold
pressure requirements.
Also due to the input rating reduction required at high
altitudes, the output rating of the appliance is reduced and
should be compensated for in the sizing of the equipment for
application.
FEATURES
(SELF-CLEANING SYSTEM)
These units include self-cleaning device (Self-Cleaning
System) installed in the front water inlet. See figure 2. The
Eliminator must be oriented correctly for proper function. There
is a marked range on the pipe nipple portion of the Eliminator,
that must be aligned with the top of the inlet spud. A label above
the jacket hole has an arrow that will point to the marked portion
of the pipe nipple if the orientation is correct. If the arrow does
not point within the marked range on the pipe nipple, adjust
the pipe nipple to correct. A pipe union is supplied with the
Eliminator to reduce the probability of misaligning the Eliminator
accidentally while tightening the connection to the inlet water
supply line. Improper orientation of the Eliminator can cause
poor performance of the heater and can significantly reduce
outlet water temperatures during heavy draws.
NOTE: The inlet tube may have 1, 3 or 7 cross-tubes.
FIGURE 2
For proper function, The Eliminator must be oriented correctly.
There is a marked range on the pipe nipple that must be aligned
with the top of the inlet spud (check for label on the appliance)
to assure proper orientation. Please check to confirm that the
marked range is in alignment with the top of the spud. A pipe
union is supplied with The Eliminator to help eliminate the
possibility of changing the orientation by accidentally over-
tightening the inlet supply line. Improper orientation of The
Eliminator may cause temperature build-up issues or spells of
colder than usual water temperatures.
HIGH LIMIT SWITCH
The digital thermostat (Fig. 3) contains the high limit (energy
cutoff) sensor. The high limit switch interrupts main burner gas
flow should the water temperature reach 203°F (95°C).
In the event of high limit switch operation, the appliance
cannot be restarted unless the water temperature is reduced to
approximately 120°F (49°C). The high limit reset button on the
front of the control then needs to be depressed.
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