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(3600 seconds).
3. If the 1/2 cu. ft. dial was used, multiply your number
X 2. EXAMPLE: If it took 23 seconds to complete one
revolution of the 1/2 ft. dial (23 x 2 = 46).
This tells us that at this rate, it would take 46 seconds to
consume one cu. ft. of gas. This tells us that in one hour,
the furnace would consume 78 cu. ft. of gas. (3600/46 =
78) The typical value range for 1 cu. ft. of natural gas is
around 1025 BTU. Check with your gas utility, if possible.
In this example, the furnace is consuming 80,000 BTUH.
NOTE: The final manifold pressure cannot vary by more
than ± 0.2" w.c. for Natural from the specified setting.
Consult your local gas supplier if additional input rate
adjustment is required.
4. Turn ON gas and relight appliances turned off in step
1. Ensure all the appliances are functioning properly
and that all pilot burners (if applicable) are operating.
Temperature Rise
Air temperature rise is the temperature difference between
supply and return air. The proper amount of temperature rise
is usually obtained when the unit is operated at the rated input
with the "as shipped" blower speed. If the correct amount
of temperature rise is not obtained, it may be necessary to
change the blower speed.
Temperature rise must be within the range specified on the
unit rating plate. An incorrect temperature rise may result in
condensing in or overheating of the heat exchanger. An airflow
and temperature rise table is provided in the Specification
Sheet applicable to your model. Determine and adjust
temperature rise as follows:
Temperature Rise Measurement
1. Operate furnace with burners firing approximately
15 minutes. Ensure all registers are open and all
duct dampers are in their final (fully or partially open)
position.
2. Place thermometers in the return and supply ducts as
close to the furnace as possible. Thermometers must
not be influenced by radiant heat by being able to "see"
SUPPLY
AIR
RETURN
AIR
Figure 12
the heat exchanger.
3. Subtract the return air temperature from the supply
air temperature to determine the air temperature rise.
Allow adequate time for thermometer readings to
stabilize.
4. Adjust temperature rise by adjusting the circulator
blower speed. Increase blower speed to reduce
temperature rise. Decrease blower speed to increase
temperature rise. Refer to the following section for
speed changing details.
Circulator Blower Speed Adjustment
T
O AVOID PERSONAL INJURY OR DEATH DUE TO ELECTRICAL SHOCK
OFF
TURN
POWER TO THE FURNACE BEFORE CHANGING SPEED TAPS
This furnace is equipped with a multi-speed circulator blower. This
blower provides ease in adjusting blower speeds. The Specifi-
cation Sheet applicable to your model provides an airflow table,
showing the relationship between airflow (CFM) and external
static pressure (E.S.P.), for the proper selection of heating and
cooling speeds.
1. Determine the tonnage of the cooling system installed with
the furnace. If the cooling capacity is in BTU/hr divide it by
12,000 to convert capacity to tons.
Example: Cooling Capacity of 30,000 BTU/hr.
30,000/12,000 = 2.5 Tons
2. Determine the proper air flow for the cooling system. Most
cooling systems are designed to work with air volume
between 350 and 450 CFM per ton. Most manufacturers
recommend an air flow of about 400 CFM per ton.
Example: 2.5 tons X 400 CFM per ton = 1000 CFM
3. Select the heating speed for your model from the
heating speed chart in the Specification Sheet. The
selected speed must provide a temperature rise within
the rise range listed with the particular model.
Continuous Fan Mode Speed Selection
To change the main blower speed in circulation mode, see
the following steps:
1. Press menu button until LED displays "FSd". Press
option button and LED will display the currently selected
speed number as Fxx (xx: Blower speed number from
1 to 9).
2. The control shall cycle through available fan speeds
every time the option button is pressed. All 9 speeds
are available for circulation.
3. When the menu button is pressed, the current displayed
speed shall stop flashing. Press the menu button again
to select the option and the control shall immediately
apply that blower setting and return to the corresponding
main menu.
21
WARNING
,
.
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Troubleshooting
