Armstrong G2D93CT - OPERATION; Heating Operation Modes

506303-01
Page 28 of 40 Issue 0938
If during a heating cycle the limit control senses an abnormally
high temperature and opens, the ignition control de-energizes
the gas valve and the combustion blower while the circulating
blower ramps up to 2
nd
stage heat speed. The circulating blower
remains energized until the limits are closed.
Fan On (see Figure 39)
When the thermostat is set for continuous fan operation
and there is no demand for heating or cooling, a call for fan
closes the R to G circuit and the circulating blower motor
runs at 50% of the selected cooling CFM until switched off.
When the call for fan is turned off, the control de-energizes
the circulating blower.
Cooling
The unit is set up at the factory for single stage cooling. For two
stage cooling operation, clip the jumper wire located between
the Y to Y2 terminals on the integrated ignition/blower control
board.
When the call for heat is satisfied, the gas valve and
combustion air blower shut down. The ignition control shuts
off the gas valve and runs the combustion blower for an
additional 15 seconds. The circulating air blower continues
to run for 2 minutes at 82% of the selected heating speed
(low fire or high fire) before ramping down.
In the event the unit loses ignition, the control will attempt
to recycle up to five times before it goes into a 1-hour lockout.
Lockout may be manually reset by removing power from
the control for more than 1 second or removing the
thermostat call for heat for more than 3 seconds.
High Heat (W2) Call
(G2D95CT/U Models)
Figure 38
W2
100*
82%*
2 min
CALL
OFF
W2 - High Heat Demand Present
- High Heat Demand Satisfied
w2
* Percentage of High Fire CFM
(see table in Figure on page )36 25
w2
Figure 37
1
st
Stage – 2
nd
Stage (W1/W2) Heat Call
(G2D95CT/U Models)
W1
100%*
CALL
W2 - High Heat Demand Present
- High Heat Demand Satisfied
w2
50%*
75%*
** Percentage of High Fire CFM
(see table in Figure on page )36 25
1
min
W1 - Heat Demand Present
- Heat Demand Satisfied
w1
* Percentage of Low Fire CFM
(see table in Figure 36 on page 25)
100%**
82%**
2 min
OFF
W1/W2
w1
w2
82%*
2 min
w1
1
min
Call for Fan
(G2D95CT/U Models)
Figure 39
G
g
50%
CALL OFF
G - Fan Switch ON
- Fan Switch OFF
g