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5.
The blower door is in place, closing the
door switch in the line voltage circuit.
6.
The gas line has been purged
and all
connections
are leak tight.
Start=Up
Procedure
1.
Set the thermostat
to the lowest setting.
2.
Close the disconnect(s)
to provide
line
voltage to the furnace.
3.
Follow the procedures
given on the oper-
ating
instructions
label attached
to the
furnace.
4.
Set the thermostat
above room tempera-
ture and verify the sequence of operation.
(See the SEQUENCE
OF OPERATION.)
.
After the furnace has run for approximately
five minutes, set the thermostat below room
temperature
and verify steps 9 - 11 of the
SEQUENCE
OF OPERATION
(page 31).
Shut
Down
Procedure
In the event that the furnace must be shut down,
follow this procedure:
1.
Set the room thermostat
to "OFF" or its
lowest temperature
setting.
2.
Turn OFF the main gas supply to the appli-
ance at the manual valve outside of the
appliance casing.
3.
Remove
the control access
panel / Iou-
vered door.
.
.
Move the appliance
gas valve lever/knob
to the "OFF" position.
Turn
OFF the electrical
power
to the
appliance.
Verifying
Firing
Rate
The firing rate must be verified for each instal-
lation to prevent over-firing
the furnace.
NOTE: The firing
rate must not exceed
the
rate shown
on the furnace
rating
plate. At
altitudes
above 4000 ft. it must not exceed
that on the rating
plate less 4% for each
1000 ft.
Use the following
procedure
to determine
the
firing rate:
1.
Shut off all other gas fired appliances.
2.
Start the furnace and allow it to run for at
least three minutes.
.
.
.
Measure the time (in seconds) required for
the gas meter to complete one revolution.
Convert the time per revolution
to cubic
feet of gas per hour using Table 9. See
page 28.
Multiply the gas flow rate in cubic feet per
hour bythe heating value of the gas in Btu
per cubic foot to obtain the firing rate in
Btuh. Example:
*
Time for 1 revolution
of a gas meter
with a 1 cubic foot dial = 60 seconds.
*
From Table 9 read 60 cubic feet per
hour of gas.
*
Heating
value of the gas (obtained
from gas supplier)
= 1000 Btu per
cubic foot.
*
Firing rate = 1000 x 60 = 60,000 Btuh.
6.
See the "High Altitude Derate" section for
additional
information
on firing rate at el-
evations
above 4,000 ft.
The gas valve regulator is set at a nominal value
of 3.5 in. water column for use with natural gas.
The manifold pressure must be set at 10.0 in.
water column for use with LP gas.
Verifying
and Adjusting
Temperature
Rise
Verify that the temperature
rise through
the
furnace is within the range specified on the fur-
nace rating plate. Temperature
rises outside the
specified
range could result in premature heat
exchanger failure.
Place thermometers
in the return and supply
air stream as close to the furnace as possible.
The thermometer
on the supply air side must
be shielded from direct radiation from the heat
exchanger
to avoid false readings. Adjust all
registers
and duct dampers
to the desired
position and run the furnace for fifteen minutes
before taking any temperature
readings.
The
temperature
rise is the difference
between the
supply and return air temperatures.
For typical duct systems, the temperature
rise
will fall within the range specified on the rating
plate with the blower
speed
at the factory
recommended
setting, if the temperature
rise
measured is outside the range specified, it may
be necessary
to change
the blower
speed.
Lower blower speeds will increase the tem-
perature
rise and higher blower
speeds will
decrease
the temperature
rise.
27
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