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n
b. When thermometer readings stabilize, subtract return-
air temperature from supply-air temperature to determ-
ine air temperature rise.
NOTE:
Blower
access door must be installed for proper
temperature rise measurement.
NOTE:
If the temperature rise is outside this range, first check:
•
Gas input for heating operation.
•
Derate for altitude if applicable.
•
Return and supply ducts for excessive restrictions caus-
ing static pressures greater than 0.50-In. W.C.
•
Dirty filter.
ELECTRICALSHOCK
HAZARD
Failure to follow this warning
could result in personal
injury or death.
Disconnect 115-v electrical power and install lockout tag
before changing speed tap.
c. Adjust air temperature rise by adjusting blower speed.
Increase blower speed to reduce temperature rise.
Decrease blower speed to increase temperature rise.
d. Turn thermostat down below room temperature and
remove blower access door.
e. To change motor speed selection for heating, remove
blower motor lead from control HEAT terminal (See
Fig. 25.) Select desired blower motor speed lead from
one of the other terminals and relocate it to the HEAT
terminal (See Table 11 for lead color identification).
Reconnect original lead to SPARE terminal.
COLOR
White
Black
Yellow'i-
Blue*
Red*
Table ll--Speed
Selection
SPEED
Common
Hiqh
Med-Hiqh
Med - Low
Low
AS SHIPPED
BLW
COOL
SPARE
SPARE
HEAT
1/5 HP motor models: BLUE to HEAT,REDto SPARE
Not available
on 1/5
HP motors.
NOTE: Continuous blower is the HEATspeed.
f. Repeat
steps a through
e.
g. When correct input rate and temperature
rise is
achieved,
turn gas valve
ON/OFF
switch to OFF.
h. Remove
manometer
or similar
device from gas valve.
i. Reinstall
manifold
pressure
tap plug in gas valve.
FURNACE
OVERHEATING
HAZARD
Failure to follow this caution may result in reduced furnace
life.
Recheck
temperature
rise. It must be within limits specified
on
the
rating
plate.
Recommended
operation
is at the
midpoint
of rise range or slightly
above.
6. Set thermostat heat anticipator.
a. Mechanical thermostat - Set thermostat heat anticipat-
or to match the amp. draw of the electrical components
in the R-W circuit. Accurate amp. draw readings can
be obtained at the wires normally connected to ther-
mostat subbase terminals, R and W. The thermostat
anticipator should NOT be in the circuit while measur-
ing current. (1.) Remove thermostat from subbase or
from wall. (2.) Connect an amp. meter as shown in
Fig. 44 across the R and W subbase terminals or R and
W wires at wall.
(3.) Record amp. draw across terminals when furnace
is in heating and after blower starts.
(4.) Set heat anticipator on thermostat per thermostat
instructions and install on subbase or wall.
b. Electronic thermostat: Set cycle rate for 4 cycles per
hr.
7. Adjust blower off delay The blower off delay has 4 ad-
justable settings from 90 sec to 180 sec. The blower off
delay jumpers are located on the furnace control board.
(See Fig. 25.) To change the blower off delay setting,
move the jumper from one set of pins on the control to the
pins used for the selected blower off delay. Factory off
delay setting is 120 sec.
8. Set airflow CFM for cooling Select the desired blower
motor speed lead for cooling airflow. See Table 4-Air De-
livery-CFM
(With Filter). See Table 11
for lead color
identification.
FIRE
HAZARD
Failure to follow this warning could result in personal
iniury, death and/or property damage.
Reinstall
manifold
pressure tap plug in gas valve to
prevent gas leak.
j. Reinstall blower access door if removed.
k. Turn gas valve ON/OFF switch to ON.
34
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