Bryant 987MB Installation, Start-Up, Operating And Service And Maintenance Instructions page 57

987MB: Installation, Start-up, Operating and Service and Maintenance Instructions
To lock the furnace in Maximum 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 Maximum 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 and
SW1-3 is set to OFF, airflow is raised 10% for Minimum Heat,
7.5% for Intermediate Heat and 17.5% for Maximum Heat. Factory
default position is ON. If SW1-3 is ON and SW1-4 is OFF, airflow
is raised 18% for Minimum and Intermediate heat and 10% for
Maximum Heat.
5. Turn 115 VAC power on.
6. Re-check Maximum 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 and SW4-2 to the OFF position unless
two-stage thermostat operation is desired, see
4. Proceed to "Adjust Blower Off Delay" or install blower door if
complete.
WARNING
!
FIRE HAZARD
Failure to follow this warning could result in personal injury, death,
and/or property damage.
Reinstall manifold pressure tap plug in gas valve to prevent gas leak.
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 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 12 and
Table 18 – 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 airflow for low-speed or
high-speed cooling, see Table 5
Fig. 60 - Furnace Setup Switches and Descriptions. Depending on the
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Fig. 60.
Fig. 37, Fig. 60 andFig. 74.)
SETUP SWITCH
(SW1-7 AND -8)
POSITION
SW1-7 SW1-8
OFF OFF
ON OFF
OFF ON
ON ON
- Air Delivery - CFM (With Filter) and
model size, the cooling airflow can be adjusted from 1.5 to 6 tons based
on 350 CFM ton.
NOTE: 6 ton airflow will truncate at 2200 CFM on applicable models.
Air Conditioning Setup Switch SW2
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
other CFM per ton Setup switch selections, see
Fig. 66.
Continuous Fan (CF) Setup Switch SW3
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
two-speed cooling or heat pump unit. Adjust SW3 to match the airflow
required for low-speed cooling. Select the required airflow from
and Fig. 60.
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. 60.
NOTE: The airflow settings for SW2 and SW3 selections are the same
for high and low stage cooling, EXCEPT for the default values, see
Table 5. For a complete explanation of cooling airflow, refer to the
section titled "Sequence of Operation."
NOTE: The airflow table for continuous fan is different than the airflow
table for low stage cooling, see
Adjust Continuous Fan Airflow (and Low-Speed
Cooling Airflow)
Adjust continuous fan and low-stage cooling airflow using SW3 and
refer to Fig. 60.
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 from
Thermostat."
10 TURNS
EXAMPLE: 5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
Fig. 66 – Amp. Draw Check with Ammeter
Adjust 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
57
5. Table is based upon 350 CFM per ton. For
Fig. 37,
Table 5.
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AROUND
AMMETER
R Y W G
FROM UNIT 24-V
CONTROL TERMINALS
= 0.5 AMPS FOR THERMOSTAT
ANTICIPATOR SETTING
Fig. 60 and
Table 5
Fig. 37 and
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