Armstrong Air Conditioning A96DS2V - Application Using a Single Stage Thermostat

507405-05 Page 59 of 72Issue 1621
Application Using a Single Stage Thermostat
B - Heating Sequence - Integrated Control Thermostat
Selection DIP switch 1 ON in “Single-Stage” Position
NOTE: In these applications, two-stage heat will be initiated
by the integrated control if heating demand has not been
satised after the eld adjustable period (7 or 12 minutes).
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 low speed.
2. Once the control receives a signal that the low pressure
switch has closed, the combustion air inducer begins a
15 second prepurge in low speed.
NOTE: If the low re pressure switch does not close the
combustion air inducer will switch to high re. After
a 15 second pre-purge the high re pressure switch
will close and the unit will begin operation on high re.
After 10 to 20 seconds of high re operation the unit
will switch to low re.
3. After the prepurge is complete, a 20 second initial ignitor
warm-up period begins. The combustion air inducer
continues to opeate at the ignition speed.
4. After the 20-second warm-up period has ended, the
gas valve is energized on low re (rst stage) 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 on the low re heating speed and
the HUM contacts are energized. The integrated control
also initiates a second-stage on delay (factory-set at 7
minutes; adjustable to 12 minutes).
5. If the heating demand continues beyond the second-
stage on delay, the integrated control energizes the
combustion air inducer at high speed. The control also
checks the high re (second stage) pressure switch
to make sure it is closed. the high re (second-stage)
gas valve is energized and the indoor blower motor is
energized for operation at the high re heating speed.
6. When the thermostat heating demand is satised, the
combustion air inducer begins a 5-second low speed
post-purge. The eld-selected indoor blower off delay
begins. The indoor blower operates at the low-re
heating speed.
7. 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.
Figure 59
Figure 58