*TM 10-7310-281-13&P - JATONKAM35s HOME ON THE WEB

TM 10-7310-281-13&P 0003
OPERATOR AND FIELD MAINTENANCE
THEORY OF OPERATION
Electrical Supply
A 24VDC supply is connected to the power connector (Figure 1, Item 1). Voltage is then supplied to the
controller (Figure 1, Item 2), which contains all vital electrical circuits.
Fuel Supply
The fuel tank (Figure 1, Item 3) is filled either through the fuel tank fill plug (Figure 1, Item 4), before the
MBU is installed into an appliance, by connecting a quick disconnect hose to the fuel fill nipple (Figure 1,
Item 5) and the feed adapter on a fuel can, turning the burner control (Figure 1, Item 6) to HIGH (START),
then pressing the FUEL button (Figure 1, Item 7). This energizes the air compressor (Figure 1, Item 8)
and opens the tank fill valve (Figure 1, Item 9) (requires electrical power connection). A full tank of fuel
allows up to a minimum of five hours of operation before the MBU shuts down. A check valve (Figure 1,
Item 10) prevents fuel from entering the air line during shipping and handling.
Power-Up
MBU power-up is initiated by pressing the power switch (Figure 1, Item 11). This tests the indicator lights
(Figure 1, Item 12) for three seconds. The hour meter (Figure 1, Item 13) back light illuminates to indicate
the power-up condition. The digital numbers will sequence before setting on actual accumulated operating
hours.
Start-Up
With burner control (Figure 1, Item 6) in HIGH (START) position, MBU startup is initiated by pressing the
START button (Figure 1, Item 14), which energizes the igniter (Figure 1, Item 15). After two seconds, the
compressor (Figure 1, Item 8) starts, and the fuel valve (Figure 1, Item 17) on the fuel delivery block
assembly (Figure 1, Item 18) opens, allowing fuel to flow to the nozzle (Figure 1, Item 19). The vent valve
(Figure 1, Item 20) on the fuel tank (Figure 1, Item 3) opens, allowing air to enter the fuel tank. The
compressor (Figure 1, Item 8) draws air through the air filter (Figure 1, Item 21) on the fuel delivery block
assembly (Figure 1, Item 18), pressurizing the fuel nozzle (Figure 1, Item 19). Simultaneously, fuel is
drawn from the fuel tank (Figure 1, Item 3) through a 30-micron filter (Figure 1, Item 22) and a zero
pressure regulator (Figure 1, Item 23) to the burner control valve (Figure 1, Item 24), which regulates the
flow to the nozzle (Figure 1, Item 19). This fuel-air mixture is sprayed into the burner (Figure 1, Item 25) in
a fine mist and ignited. The igniter circuit remains energized for 30 seconds.
NOTE
Holding down the START button will override the fault detection circuitry, preventing
shutdown for two minutes. This allows purging of the fuel lines on new units and on units
that have been completely drained. It also facilitates troubleshooting.
Actions During Operation (After warm-up is complete)
Adjust the burner control (Figure 1, Item 6) as necessary.
Automatic Shutdown
The following are the usual causes of an automatic shutdown:
• Loss of combustion. If the flame sensor (Figure 1, Item 26) fails to verify combustion, the MBU shuts
down immediately and the red SERVICE indicator (Figure 1, Item 27) lights.
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