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THERMOSTAT SETTINGS
1.
The Excel 10 temperature con trol ler is adjusted
to a low test setting when shipped from the factory.
2.
Using
the
Command
temperature set point to the lowest settings which
will satisfy hot water demands and prevent a risk
of scald injury.
TEMPERATURE ADJUSTMENT
Inlet water temperatures below the specified minimum
recommendations can excessively cool the products of combustion
resulting in condensation on the primary heat exchanger. The water
heater is designed to condense only on the secondary heat
exchanger. Condensation on the primary heat ex chang er can cause
operational problems, bad combustion, sooting, flue gas spill age
and reduced service life of the related components.
A minimum water temperature has been established for each model
based on the Btu/hr input at 100% of rated burner input. The
temperature set point for the Excel 10 controller sensing stored
water temperature must not be set lower than the specified
minimum for each model. Maintaining inlet water temperatures to
the water heater equal to or higher than the specified minimum
ensures proper op er a tion of the bypass and allows all con den sate
formation to occur on the sec ond ary heat exchanger. A water
heater allowed to sustain operation at water temperatures lower than
the specified minimum may not provide enough heat from the
burner to maintain water temperatures in the primary heat
exchanger above the 130°F (55°C) dew point of flue products.
Operation of a water heater at a temperature below the spec i fied
minimum will result in non-warrantable operational problems from
the condensate formation on the primary heat exchanger.
FIG. 87 Warning Label
Display,
adjust
• Water temperature over 125°F (52°C)
can cause severe burns instantly or
death from scalds.
• Children, disabled and elderly are
at highest risk of being scalded.
• See instruction manual before
setting temperature at heating
appliance.
• Feel water before bathing or showering.
• If this appliance is used to produce
water that could scald if too hot,
such as domestic hot water use,
adjust the outlet control (limit) or use
temperature limiting valves to obtain
a maximum water temperature of
125°F (52°C).
Minimum Inlet Water Temperatures
Input
Minimum Return
Btu/hr
Temperature
the
1,500,000
___________
____________________
1,700,000
___________
____________________
2,000,000
An appliance allowed to op er ate with return temperatures
set point below the specified minimum settings may ex peri -
ence operational problems with the operating controls and
safety switches, obstruction of the flue gas passages on the
primary heat exchanger, incomplete combustion and
possible flue gas spill age. Operation at lower than specified
water temperatures may cause hazardous conditions that
result in non-war rant able damage to the appliance.
The maximum temperature set point that can be programmed
into the Excel 10 controller from the Command Display for
water heater operation is 190°F (87.8°C). The Excel 10 control
is factory pre-set at approximately 120°F (48.9°C). Facilities
with small children or invalids may require 120°F (48.9°C) or
lower temperature setting to reduce risk of scald injury. Some
states may require a lower temperature setting. Check with
your gas supplier for local requirements governing the
temperature setting. Remember, no water heating system will
provide exact temperature at all times. Allow a few days of
operation at this setting to determine the correct temperature
setting consistent with your needs.
The following chart (Table II) details the relationship of water
temperature and time with regard to scald injury and may be used
as a guide in determining the safest water temperature for your
applications.
APPROXIMATE TIME / TEMPERATURE RE-
LATIONSHIPS IN SCALDS
120°F
125°F
130°F
135°F
140°F
145°F
150°F
155°F
75
TABLE - HH
Minimum
Setpoint
50°F (10°C)
105°F (40.6°C)
_______________
50°F (10°C)
90°F (32.2°C)
_______________
50°F (10°C)
70°F (23.9°C)
CAUTION
TABLE - II
More than 5 minutes
1 1/2 to 2 minutes
About 30 seconds
About 10 seconds
Less than 5 seconds
Less than 3 seconds
About 1 1/2 seconds
About 1 second
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