70
2. Restore furnace to normal operating condition.
a. Turn gas valve ON/OFF switch to OFF.
b. Remove water column manometer or similar device from
manifold pressure tap.
FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Manifold pressure tap set screw must be tightened or
⅛
--in.
NPT pipe plug must be installed to prevent gas leaks.
!
WARNING
c. Tighten set screw on manifold pressure tap with 3/32--in
hex wrench, or if 1/8--in. NPT plug was removed, apply
pipe dope sparingly to end of plug and reinstall in the gas
valve.
d. Turn gas valve ON/OFF switch to ON.
e. Move setup SW1--2 on furnace control to position required
for attached thermostat (OFF for single-stage thermostats,
ON for two-stage thermostats).
f. Check for gas leaks and verify furnace operation.
Adjust Temperature Rise
NOTE
: Blower door must be installed when taking temperature
rise reading. Leaving blower door off will result in incorrect
temperature measurements, due to possible changes in duct static
pressure and airflow.
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.
CAUTION
!
When setup switch SW1--4 is ON, operation will be near the high
end of the rise range for improved comfort.
Furnace must operate within ranges of temperature rise specified
on the furnace rating plate. Determine air temperature rise as
follows:
a. Place thermometers in return and supply ducts as near fur-
nace as possible. Be sure thermometers do not see heat ex-
changer so that radiant heat does not affect readings. This
practice is particularly important with straight--run ducts.
b. When thermometer readings stabilize, subtract return--air
temperature from supply--air temperature to determine air
temperature rise.
NOTE
: Temperature rise can be determined for low--heat and
high--heat operation by locking the furnace in each mode of
operations. The mode of operation is based on the position of
Setup Switch SW1--2 on the furnace control board.
c. This furnace is capable of automatically providing proper
airflow to maintain the temperature rise within the range
specified on furnace rating plate. If temperature rise is out-
side this range, proceed as follows:
(1.) Check gas input for low-- and high--heat operation.
(2.) Check derate for altitude, if applicable.
(3.) Check all return and supply ducts for excessive
restrictions causing static pressure greater than
0.5--In. W.C.
(4.) Ensure setup switch SW1--4 (See Fig. 38 for
switch location.
(5.) Make sure proper model plug is installed.
To lock the furnace in low heat:
1. Turn SW1--2 ON at the furnace control.
2. Connect a jumper across R and W/W1 at the thermostat
terminals at the furnace control.
3. Allow the burners to ignite and the blower to turn on.
4. Allow the supply temperature to stabilize and verify the
proper rise range.
If the temperature rise is too high or too low in low heat:
1. Remove jumpers from R and W/W1.
2. Wait until the blower off delay is completed.
3. Turn 115 VAC power off.
4. Check the position of setup switch SW1--4. When set to
OFF, airflow is raised 7% for low heat. Factory default
position is ON.
5. Turn 115 VAC power on.
6. Re--check low heat temperature rise.
To lock the furnace in high heat:
1. Connect a jumper across R and W/W1 and W2 at the
thermostat terminals at the furnace control.
2. Allow the burners to ignite and the blower to turn on.
3. Allow the supply temperature to stabilize and verify the
proper rise range.
If the temperature rise is too high or too low in high heat:
1. Remove jumpers from R and W/W1 and W2.
2. Wait until the blower off delay is completed.
3. Turn 115 VAC power off.
4. Check the position of setup switch SW1--4. When set to
OFF, airflow is raised 7% for low Heat, and 10% for high
heat. Factory default position is ON.
5. Turn 115 VAC power on.
6. Re--check high heat temperature rise.
After the temperature rise has been verified:
1. Remove jumpers from thermostat terminals.
2. Allow the blower off delay to complete.
3. Turn set--up switches SW1--2 to the OFF position unless
two--stage thermostat operation is desired. See Fig. 65.
4. Proceed to “Adjust Blower Off Delay” or install blower
door if complete.
Adjust Blower Off Delay (Heat Mode)
a. Remove blower door if installed.
b. Turn Dip switch SW--7 or SW--8 ON or OFF for desired
blower off delay. See Table 19 and Fig. 38, 65 and 72.
Adjust Cooling Airflow – High-Speed and
Low-Speed Cooling
The ECM blower can be adjusted for a range of airflows for
low-speed or high-speed cooling. See Table 9 – Air Delivery –
CFM (With Filter ) and Fig. 65 – Furnace Setup Switches and
Descriptions. Depending on the model size, the cooling airflow
can be adjusted from 1.5 to 6 tons based on 350 per CFM ton.
NOTE
: 6 ton airflow will truncate at 2200 CFM on applicable
models.
The high-speed or single-speed cooling airflow is adjusted by
turning Setup switches SW2-1, SW2-2 and SW2-3 either ON or
OFF. Select the required airflow from Table 9. Table 9 is based
upon 350 CFM per ton. For other CFM per ton Setup switch
selections, see Fig. 38, Fig. 65 and Fig. 72.
