Manual High Limit ( All models )
If any situation occurs creating a
temperature reaching 200° F at the air
discharge, power to the gas train
circuitry will be terminated. At this point
none of the operating components of the
gas train will function. To reactivate the
gas train the reset button on the limit
switch must be depressed. The main
application of this heater is for use with
a paint spray booth and a additional high
limit thermostat is provided for use in
the spray mode to shut down the gas
train if the discharge air temperature
reaches 165 deg. F. This high limit is
automatically resetting.
Air Flow Sensor ( All models )
Air flow sensors are connected directly
to the flame guard device.When a loss or
lack of air flow, or to much air flow
across the burner is sensed, the flame
guard device will terminate power to the
pilot solenoid and the connection of the
temperature controller to the gas train
modulator. The through-put air around
the burner will need to be reestablished,
or reduced for the burner to fire.
Flame Guard Device ( All models )
The flame guard is a device that will
check the burner for pilot during
initiation and for pilot and main flame
during full operation. The flame guard
device uses a flame rod installed in the
burner which will thermally induce a 15
- 18 volt DC signal in the flame guard
device. During initiation there is a 10
second trial period. At the end of this
time if there is no flame in the pilot area,
the flame guard will lock out the burner
system. The flame guard will need to be
manually reset to start initiation. It does
not re-attempt initiation automatically.
The flame guard is a “one try” system
that will require manual reset each time
the device locks out. When a flame
depletes or disappears in the burner
during full operation, the flame guard
will have a 10 second delay and will
lock out the burner system. The flame
guard will need to be manually reset at
this point.
Temperature Control System
( Models 99270 )
The system uses an analog temperature
controller with analog input and a 100%
symmetrically modulating gas valve.
The thermister connected to the
temperature control will be placed in the
air output of the make up air unit. The
temperature controller internally limits
the discharge temperature to 170° F
when shipped. The manual high limit
will act as a back up to this.
Temperature Control System
( Models 99273 and 99275 )
This system uses a digital temperature
controller, a 100% modulator and a
symmetrically modulating gas valve.
The thermocouple connected to the
temperature control will be placed in the
air output of the make up air unit. The
temperature controller internally limits
the discharge temperature to 190° F
when shipped. The manual high limit
will act as a back up to this.
FREEZE THERMOSTAT
( All Models )
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Summary of Contents for 99270
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