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935CA: Installation, Start-up, Operating and Service and Maintenance Instructions
e. Check for gas leaks and verify furnace operation.
7. Set temperature rise. The furnace must operate within the
temperature rise ranges specified on the furnace rating plate.
Determine the temperature rise as follows:
NOTE: Blower access door must be installed when taking temperature
rise reading. Leaving blower access door off will result in incorrect
temperature measurements.
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in:
Overheating the heat exchangers or condensing flue gases in heat
exchanger areas not designed for condensate.
Shortened furnace life
Component damage
Temperature rise must be within limits specified on furnace rating plate.
Recommended operation is at midpoint of rise range or slightly above.
WARNING
!
ELECTRICAL SHOCK 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.
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 close to furnace
as possible. Be sure thermometers do not see radiant heat from
heat exchangers. Radiant heat affects temperature rise 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: If the temperature rise is outside this range, first check:
(1.) Gas input for heating operation.
(2.) Check derate for altitude, if applicable.
(3.) Return and supply ducts for excessive restrictions causing
static pressures greater than the maximum heating static
listed on the rating plate.
(4.) Ensure setup switch SW1-4. See
(5.) Make sure proper model plug is installed.
If the temperature rise is too high or too low:
c. Remove jumpers from thermostat connections.
d. Wait until the blower off-delay is completed.
e. Turn 115 VAC power off.
f. Check the position of setup switch SW1-4. When set to OFF,
airflow is raised 10% for heating. Factory default position is ON.
g. Turn 115 VAC power on.
h. Recheck heating temperature rise. After the temperature rise has
been verified:
(1.) Remove jumpers from thermostat terminals.
(2.) Allow the blower off-delay to complete.
(3.) 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 SW1-7 or SW1-8 ON or OFF for desired blower
off delay. See
Table 25
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 42
for switch location.
and
Fig.
65.
Table 25 – Blower Off Delay Setup Switch
DESIRED HEATING MODE
BLOWER OFF DELAY (SEC.)
90
120
150
180
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 11
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
ton. For other CFM per ton Setup switch selections, see
Fig.
65.
The Continuous Fan airflow selection via Setup switches SW3 is also the
switch setting for low-speed cooling when the furnace is used with a
2-speed cooling or heat pump unit. Adjust the Continuous Fan CFM
Setup switches SW3 to match the airflow required for low-speed
cooling. Select the required airflow from
NOTE: The airflow selected via SW3 (Low-Speed Cooling Airflow)
cannot exceed the airflow selected via SW2 (High-Speed Cooling
Airflow). For other CFM per ton Setup switch selections, see
Fig.
65.
NOTE: The cooling airflow settings for SW2 and SW3 selections are
the same, EXCEPT for the default values. See
For a complete explanation of cooling airflow, refer to the section titled
"Sequence of Operation."
Adjust Continuous Fan Airflow (and Low-Speed
Cooling Airflow)
Adjust continuous fan and low-stage cooling airflow using SW3 and
refer to
Fig. 42
and
Table
11. The continuous fan speed can be further
adjusted at a conventional thermostat using the continuous fan speed
select function. Changing the continuous fan speed at a conventional
thermostat DOES NOT change the low-speed cooling airflow selected
via SW3 at the control board. Refer to the section titled "continuous
Blower Speed selection for Thermostat."
Set Thermostat Heat Anticipator
1. Mechanical thermostat - Set thermostat heat anticipator to match
the amp. draw of the electrical components in the R-W/W1 circuit.
Accurate amp. draw readings can be obtained at the wires normally
connected to thermostat subbase terminals, R and W. The
thermostat anticipator should NOT be in the circuit while
measuring current.
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Gas valve outlet pressure tap must be tightened to prevent gas leak.
52
SETUP SWITCH
(SW1-7 AND -8)
POSITION
SW1-7
OFF
ON
OFF
ON
– Air Delivery – CFM (With Filter).
11.
Table 11
is based upon 350 CFM per
Table 11
and
Fig.
Table
11.
WARNING
SW1-8
OFF
OFF
ON
ON
Fig. 42
and
65.
Fig. 42
and
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