Simultaneous Call For Low And High Heat; Operation Using A Single Stage Heating Thermostat; Low Stage Cooling Mode Sequence - Goodman GMEC96 Series Service And Troubleshooting

SYSTEM OPERATION

SIMULTANEOUS CALL FOR LOW AND HIGH HEAT

A call for both stages of heat will establish low fire before
going to high fire

Operation Using a Single Stage Heating Thermostat

Using a single stage thermostat, the options for high fire delay
are: 10 minutes; 20 minutes; or auto
• The automatic second stage logic is a method of
energizing the second stage valve based on the recent
average of the heating duty cycle. During a typical
heating day there will be at least one call for heat within
a 3 hour period, and usually much more often. During
this mode the low to high stage delay is determined by
using the average calculated duty cycle from the table
below. Once the specified delay time has expired the
second stage valve will be energized
• On the heating cycle following a period of 3 hours (or
greater) in which there is no call for heat, the second
stage valve will energize based on the average
calculated duty cycle prior to the three hour no call for
heat. If the average calculated duty cycle is less than
50%, then the low to high stage delay will be determined
from the table below. In this case, an assumption is made
that the outside temperature is fairly mild and the long
time between calls for heat was due to a low thermal
loss in the building. Going quickly to second stage heat
is not required in this instance.
• If the average calculated duty cycle is 50% or greater,
then the heating cycle will be treated as if high stage
is needed and the transition from low to high stage
delay will happen quickly. In this case an assumption
is made that the outside temperature is cold and that
the thermostat is likely coming out of setback. Since
assumptions are being made during this heating cycle
the duty cycle for this heat cycle will not be used in the
average calculated duty cycle formula for future heating
cycles.
• The duty cycle is calculated every cycle and used
during the next cycle. The equation for the duty cycle is
calculated as follows: Duty Cycle = (Time the appropriate
stage is ON) / (Time of the complete cycle).
• The average calculated duty cycle is determined by
averaging the previous average calculated duty cycle
with the duty cycle from the previous cycle. This places a
large emphasis on the previous cycle but allows a large
variation in any one duty cycle to be averaged out after
just a few complete heating cycles.
• If there is no load activity for 24 hours or more then set
the Duty Cycle = 100%
• The initial default average calculated duty cycle = 50%
40
Duty Cycle % Valve Output
0-38 1 Stage, 12 minute 2
st
38-50 1 Stage, 10 minute 2
st
50-62 1 Stage, 7 minute 2
st
62-75 1 Stage, 5 minute 2
st
75-88 1 Stage, 3 minute 2
st
88-100 1 Stage, 1 minute 2
st
Blower Off Delay Dip Switches
Purpose Switch Group Function
Heating Fan Off
S1
Delay
Blower Off Delay Dip Switches
Purpose Switch Group Function
Heating Fan Off
S3
Delay
*Factory Setting
Heat Mode Blower Off Delay Timing
COOLING MODE:

LOW STAGE COOLING MODE SEQUENCE:

• On a call for lo cool, the Ylo and G thermostat contacts
close signaling the control module.
• The LED will display a "GREEN"1 flash
• The compressor and condenser fan are energized.
The compressor is connected to the Ylo terminal of the
control module.
• The circulator fan is energized at lo cool speed after
a cool on delay. The electronic air cleaner will also be
energized.
• After the thermostat is satisfied, the compressor is de-
energized
• Following the 60 second Cool Mode Fan Off Delay
period, the cool circulator and air cleaner relay are de-
energized.
• When the call for "Ylo"and "G"are presented
simultaneously, the control will honor the Cool On delay
and keep the circulator de-energized. After the Cool
On delay, the circulator fan and air cleaner relays are
energized. The circulator fan is energized at the cool
speed. If a call for "G"is present prior to a call for "Ylo",
the circulator will remain at the FAN circulator speed
during the Cool On delay.
SINGLE COOLING STAGE THERMOSTAT OR 2ND
STAGE COOLING MODE SEQUENCE.
• On a call for cool, the Y and G thermostat contacts close
signaling the control module.
• The LED will display a "GREEN"2 flash
• The compressor and condenser fan are energized. The
compressor is connected to the Y terminal of the control
module.
Demand
Stage Light
nd
Stage Light to Average
nd
Stage Average
nd
Stage Average to Heavy
nd
Stage Heavy
nd
Stage Heavy
nd
PCBBF137
Dip Switch
1 2 3
90 OFF
120 OFF
150 ON*
180 ON
PCBBF139
Dip Switch
1 2 3
90 OFF
120 OFF
150 ON*
180 ON
4
OFF
ON
OFF*
ON
4
OFF
ON
OFF*
ON