Allied Air A80DS2V, Руководство по установке

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506892-01 Page 43 of 64 Issue 1251
OTHER UNIT ADJUSTMENTS
Primary and Secondary Limits
The primary limit is located on the heating compartment
vestibule panel. The secondary limits (if equipped) are
located in the blower compartment, attached to the back
side of the blower. These auto reset limits are factory set
and require no adjustment.
Flame Rollout Switches (Two)
These manually reset switches are located on (or inside of)
the burner box. If tripped, check for adequate combustion
air before resetting.
Pressure Switches
The pressure switch assembly (includes two switches) is
located in the heating compartment adjacent to the
combustion air inducer. These switches check for proper
combustion air inducer operation before allowing ignition trial.
The switches are factory-set and require no adjustment.
Temperature Rise
Place the unit into operation with a second-stage heating
demand. After supply and return air temperatures have
stabilized, check the temperature rise. If necessary, adjust
the heating blower speed to maintain the temperature rise
within the range shown on the unit nameplate. Increase the
blower speed to decrease the temperature rise. Decrease
the blower speed to increase the temperature rise. Failure
to properly adjust the temperature rise may cause erratic
limit operation.
Thermostat Heat Anticipation
Set the heat anticipator setting (if adjustable) according to
the amp draw listed on the wiring diagram that is attached
to the unit.
Heating Sequence of Operation
Electronic Ignition
The two-stage, variable speed integrated control used in
these units has an added feature of an internal control. The
feature serves as an automatic reset device for ignition
control lockout caused by ignition failure. After one hour of
continuous thermostat demand for heat, the control will break
and remake thermostat demand to the furnace and
sutomatically reset the control to begin the ignition sequence.
NOTE: The ignition control thermostat selection DIP switch
is factory set in the “TWO STAGE” position.
Applications Using a Two-Stage Thermostat
A-Heating Sequence - Control Thermostat Selection DIP
switch in “Two Stage” Position (Factory Setting)
1. On a call for heat, thermostat first stage contacts close
sending a signal to the integrated control. The integrated
control runs a self diagnostic program and checks high
temperature limit switches for normally closed contacts
and pressure switches for normally open contacts. The
combustion air inducer is energized at ignition speed,
Which is approximately the same as the inducer speed
at 70 percent firing rate.
2. Once the control receives a signal that the low fire
pressure switch has closed, the combustion air inducer
begins a 15 second prepurge in the ignition speed.
3. After the prepurge is complete, a 20 second initial ignitor
warm up period begins. The combustion air inducer
continues to operate at the ignition speed.
4. After the 20 second warm up period has ended, the gas
valve is energized and ignition occurs. At the same time,
the control module sends a signal to begin an indoor
blower 30 second ON delay. When the delay ends, the
indoor blower motor is energized at a speed that
matches the firing rate. After the 10 second ignition
stabilization delay expires, the inducer speed is adjusted
to the appropriate target rate. The inducer will remain
at the 70 percent speed as long as the thermostat has a
first stage heating demand.
5. If second stage heat is required, the thermostat second
stage heat contacts close and send a signal to the
integrated control. The integrated control initiates a 30
second second stage recognition delay.
6. At the end of the recognition delay and on all subsequent
calls for heat in the same heating cycle, the integrated
control energizes the combustion air inducer at high
speed. The control also checks the high fire pressure
switch to make sure it is closed. As the inducer speed
is increased to high, the indoor blower motor is adjusted
to a speed which is appropriate for the target rate.
7. When the demand for high fire (second stage) heat is
satisfied, the gas valve is de-energized and the field
selected indoor blower off delay begins. The combustion
air inducer begins a 20 second post purge period.
8. When the thermostat demand for low-fire (first stage)
heat is satisfied, the gas valve is de-energized and the
field-selected indoor blower OFF delay bergins. The
combustion air inducer begins a 5 second port-purge
period.
9. When the combustion air post purge period is complete,
the inducer, the HUM contacts as well as the 120V ACC
terminals are de-energized. The indoor blower is de-
energized at the end of the OFF delay.