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MONITOR HEATING SYSTEM
Section 1: Description
1-23 AIR PRESSURE SWITCH
This switch consists of a rubber diaphragm which
senses changes in air pressure (it is connected to
the Combustion Blower and the Heat Exchanger)
and a normally-open, micro switch.
Should an abnormal pressure differential exist,
the switch opens to disable the circuitry that con-
trols the supply of gas. Since the flow of gas to
the Burner is cut off, the flame extinguishes, and
the code
[E17] is indicated in the digital dis-
play. This safety mechanism can be triggered by
several conditions:
- Leak, loose, or broken tubing which connects
the Air Pressure Switch with the Combustion
Blower or the Heat Exchanger.
- Clogged or blocked Air Line
- Blocked or clogged Flue Pipe
- Intake port of the Combustion Blower is
blocked
- Combustion Blower is inoperable
1-24 OVERHEAT PROTECTOR SWITCH (GF3800)
The normally-closed Overheat Protector Switch
safeguards the heaters against damage due to
overheating.
The Switch is rated 115°C (239°F). Should a
Monitor overheat (internal temperatures rise be-
yond 115°C/239°F) switch will open to shut down
the heater. After extinguishing the flame, the
code
FE17J is indicated in the digital display.
The Overheat Protector Switch will automatically
reset after cooling down. Once the heater has
cooled to 90°C (194°F), the system can be re-
started. To restart the Monitor, proceed as fol-
lows:
A. Press ON/OFF Switch to OFF.
B. Allow heater to cool.
C. Troubleshoot the cause of the overheat.
D. Press ON/OFF switch to ON.
E. Proceed with normal operation.
1-25 THERMAL FUSE (GF3800)
Should Overheat Protector Switch malfunction,
and the heater be further overheated, the .ther-
mal fuse (internal temperatures rise beyond 145
°C/293°F) melts and prevent further overheating.
1-26 OVERCURRENT FUSE
2-amp., 125VAC, fuse protects the heater from
damage resulting from power overloads. In the
event of a power surge or internal wiring hazards,
the fuse opens and power to the heater is cut off.
1-27 ELECTRICAL SYSTEM
Electrical power is supplied to the Monitor to run
the Microprocessor and the other electrically-
energized component.
Electrical operation of the Monitor can be thought
of as having the following eight(8) distinct
phases: plug in; turn on; pre-purge; ignition; pre-
combustion; heating; shutdown and post-purge.
1-28 MICROPROCESSOR
Principally consisting of a 64-pin Integrated
Circuit, the Microprocessor provides safety
timings, controls relays and provides clock and
thermostat functions for the Monitor heater.
1-29 TEMPERATURE SENSOR
The sensor which is capable of sensing room
temperature within a range of 42°F to 96°F, can
be left mounted on the back of the heater cabinet
or be wall mounted.
Approximately 4
1
/
2
' (about 140cm) of No.22 AWG
Wire is supplied with the sensor to facilitate wall
mounting the sensor in a favorable location.
1-30 SAFETY MECHANISMS
Several safety mechanisms have been built into
the Monitor Heating System. These devices
protect the user against personal injury, protect
the heater against damage, and shutdown the
heater if a malfunction occurs.
1-31 CLOTH COVERED EXHAUST PIPE
Insulating cloth covers are to be placed over all
metal surfaces of the Exhaust Line during
installation. Since combustion by-products are
vented at elevated temperatures, the Exhaust
Pipe will become hot during operation. The
insulating cloth covers protect the user from bum
hazards associated with accidental contact with
these heated metal surfaces. During installation
make sure that all Exhaust Lines are tight. Do not
operate the heater without the insulating covers.
1-32 AIR CIRCULATION FAN GUARD
This guard is an integral part of the fan assembly.
The guard protects the user agrainst physical
injury which could occur from accidental contact
with revolving metal fan blade.
9
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