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Adjust Temperature Rise
Blower door must be installed when taking
NOTE:
temperature rise reading. Leaving blower door off will result
in incorrect temperature measurements, due to possible
changes in duct static pressure and airflow.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in:
S
Overheating the heat exchangers or
condensing flue gases in heat exchanger
areas not designed for condensate.
S
Shortened furnace life.
S
Component damage.
Temperature rise must be within limits specified on
furnace rating plate. Recommended operation is at
midpoint of rise range or slightly above.
Jumper R to W to check gas-heat temperature rise. Do not
exceed temperature rise ranges specified on unit rating
plate.
This furnace must operate within the temperature rise
ranges specified on the furnace rating plate. Determine the
air temperature as follows:
1. Place duct thermometers in return and supply ducts
as
close
to
furnace
thermometers do not "see" heat exchangers so that
radiant heat does not affect thermometer readings.
This is particularly important with straight−run ducts.
2. When
thermometer
return−air temperature from supply−air temperature to
determine temperature rise.
If the temperature rise is outside this range, check the
following:
1. Gas input rate.
2. Derate for altitude if applicable.
3. Return and supply ducts for excessive restrictions
causing static pressures greater than 0.50−in. w.c.
(125 Pa)
4. Adjust temperature rise by adjusting blower speed.
S
Increase blower speed to reduce temperature rise.
S
Decrease blower speed to increase temperature
rise.
WARNING
!
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Disconnect 115vac electrical power before changing
speed tap.
(Read following caution before changing taps).
CAUTION
!
UNIT DAMAGE HAZARD
To avoid operating outside the rise range and avoid
component damage:
Refer to the Air Delivery Tables to determine which
airflows and settings are allowed for proper heating
airflow.
DO NOT use the highlighted settings for
Heating airflow. The highlighted settings are to be used
for Cooling and Continuous Fan ONLY.
6
as
possible.
Be
sure
readings
stabilize,
subtract
Specifications subject to change without notice.
Change the blower speed taps as required to maintain
proper temperature rise for Heating and Cooling as
described above. To change blower motor speed selections
for heating mode, remove blower motor lead from control
HEAT terminal(s). (See Figure 2) Select desired blower
motor speed lead(s) from the other motor leads and relocate
it/them to HEAT (heating blower tap) terminal(s). Reconnect
original lead on SPARE terminal.
Adjust Blower Off Delay (Heat Mode)
If desired, the main blower off time delay period may be
lengthened or shortened when operating in the heating
mode to provide greater comfort. For position and location
of jumpers on control center. (See Figure 2 and Figure 16)
The blower off-delay has four adjustable settings from 90
sec to 180 sec. (See Table 1) To change the blower off
delay setting, move the jumper from one set of pins on the
control to the pins used for the desired blower off delay.
Factory blower off-delay setting is 120 sec.
Table 1 – Blower Off Delay Jumper Positions
PINS
1 AND 2
Time (in sec.)
90
Adjust Cooling Airflow
The cooling airflow can be set from the remaining blower
speed taps. Refer to the Air Delivery Tables in these
instructions.
CAUTION
!
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 mid--point of rise range or slightly above.
Adjust Thermostat Heat Anticipator
Mechanical thermostat: Set thermostat heat anticipator 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 thermostat sub-base
terminals, R and W. The thermostat anticipator should NOT
be in the circuit while measuring current.
1. Remove thermostat from sub-base or from wall.
2. Connect an amp. meter across the R and W
sub-base terminals or R and W wires at wall.
3. Record amp. draw across terminals when furnace is
in low heat and after blower starts.
4. Set heat anticipator on thermostat per thermostat
instructions and install on sub-base or wall.
5. Install blower access door.
Electronic thermostat: Set cycle rate for 3 cycles per hr.
Check Safety Controls
The flame sensor, gas valve, and pressure switch were all
checked in the Start−up procedure section as part of normal
operation.
1. Check Main Limit Switch
This control shuts off combustion system and
energizes air−circulating blower motor, if furnace
overheats. By using this method to check the temper-
ature limit control, it can be established that the limit is
functioning properly and that the limit will operate if
there is a restricted return−air supply or motor failure.
If the limit control does not function during this test,
the cause must be determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of
cardboard or sheet metal until the limit trips.
c. Unblock return air to permit normal circulation.
2 AND 3
3 AND 4
4 AND 5
120
150
180
440 04 6000 00
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