INTEGRATED FURNACE
CONTROLS USED ON THE LOW
PROFILE GAS FURNACE WITH
DIRECT SPARK IGNITION (DSI)
The (-)GPH / (-)GLH series of gas
furnaces now use direct spark
ignition. There are two controls: the
UTEC and Johnson Controls DSI
IFC's. As with earlier HSI controls,
both operate similarly, use remote
flame sense, and are
interchangeable.
UTEC 1028-927/928 AND JCI
G961 DAJ-2401/2402 CONTROLS
The UTEC 1028-927/928 control has
the factory part number
62-24140-02.
They are found on units with serial
numbers beginning with
FD or FF.
The Johnson Controls G961 DAJ-
2401 /2402
has the factory part
number
62-24136-02. They are found
on units with serial numbers
beginning with
FD or FF.
Both have two green and one amber
LED's. These LED's serve the same
purpose as those found on previous
hot surface ignition controls. Both
controls have on-board twinning.
Both controls use DIP switches to
select the blower off timing. They
come set for 120 seconds of blower
operation after the heat call ends.
Both controls have the
"self-
healing"
feature.
Except for the ignition method, the
operating characteristics are very
similar to the hot surface ignition
controls used with previous Low
Profile furnaces.
1. As with other electronic controls,
furnace grounding and line
voltage polarity are critical for
proper operation.
2. If this control does not detect
ignition after two attempts, it
goes into a
"self healing" mode
and operates both the main
blower and induced draft blower
for 180 seconds. It then attempts
a third ignition trial.
3. If there are four failed attempts
for ignition, or four flame failures
during one heat call, the control
goes into a "soft lock out."
4. A "soft lock out" can be reset by
cycling main power on and off, or
by cycling 24 volt power at the
thermostat.
5. The control automatically resets
after one hour in "soft lock out."
►
NOTE: The UTEC 928 and JCI 2402
controls have a replaceable 3 amp
automotive-type fuse to protect 24
volt components on the board.
Sequence of Operation
Prepurge -
1 . The thermostat calls for heat.
2. The induced draft blower (IDB) starts
and operates for the entire heat call.
3. The pressure switch(es) close.
4. The inducer operates for a 30
second pre-purge.
Ignition Trial -
1. The gas valve opens and the igniters
spark.
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FIGURE 86
2. The igniter sparks for up to 7
seconds after the gas valve
opens, or until flame recognition.
3. The burners ignite.
Flame Recognition -
1 . The flame sensor recognizes
ignition using the process of
flame rectification.
2. If flame is not proved in eight
seconds, the gas valve closes
and the IDB runs for a 30 second
inter purge.
Operation -
1. The main blower starts 20
seconds after sensing flame.
2. The inducer and burners
continue to operate.
UTEC 1028-927 DSI FURNACE CONTROL
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FIGURE87
JOHNSON CONTROLS G961 DAJ-2401 OSI FURNACE CONTROL
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