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Hot Surface Igniter (HSI)
(·)GRJ/(·)GT J
models continue to
use a silicon carbide in a ceramic
body hot surface igniter to light the
burners. This is the same igniter
used on the 80% Efficient Low
Profile furnaces. When energized,
the HSI heats to approximately
2600°. It mounts between two
burners on one side of the
burner tray.
Gas Valve
All furnaces use a 24 volt slow
opening gas valve. It delivers gas to
the burners when powered by the
Integrated Furnace Control. Manifold
pressure is maintained by an internal
pressure regulator. There are ports
on the valve to measure both line
and manifold pressure. A regulator
adjustment allows minor changes in
manifold pressure. The same type of
gas valve is on the Low Profile
furnace.
FIGURE 6
HOT SURFACE IGNITER
Remote Flame Sensor
After flame ignition, a remote flame
sensing rod proves and monitors the
flame using the process of flame
rectification. The sensor is fabricated
from Kantha1 D in a ceramic body.
Kanthal D is an alloy of aluminum,
chromium and iron. It mounts
alongside a burner on the side
opposite the igniter.
FIGURE 7
REMOTE FLAME SENSOR
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FIGURE9
FIGURE 8
GAS VALVE
Direct Spark Ignition
Current production (·)GRA/(-)GTA
units now come with direct spark
ignition. An igniter sparks to light the
burners directly. This minimizes
ignition time and electric current
draw on start up. The spark stops as
soon as the flame sensor detects
burner ignition.
DIRECT SPARK IGNITER
15
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