Lanair DHI 300 - Manual (Page 7)

Section 1 - General Specifications & Hazards
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7
Section 14 - Troubleshooting
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Burner fuel pressure gauge reading hints:
Fuel gauge fluctuates (jumps):
• Suction Line Leak.
• Air in fuel, refer to Troubleshooting Chart Item B.
• Quad ring seal for the nozzle may be damaged.
• Seal in adapter block may be worn or damaged.
• Fuel pressure regulator seal leaking or dirty.
• Suction line strainer plugged or dirty.
• Dirty Pump Screen
Reading gradually decreases:
• Fuel pump output decreasing.
• Fuel viscosity decreasing.
• Orifice in nozzle is wearing.
• Dirty Pump Screen
Reading gradually increases:
• Fuel pump output increasing.
• Fuel viscosity increasing (cold fuel, and/or gear lube).
• Orifice in nozzle is becoming plugged.
Reading drops to –0- PSI when the burner is off.
• Dirt between the diaphragm and the seat in the by-pass regulator.
• Dirt between the plunger and the nozzle seat.
• Leak in the plumbing connections.
• Leak in the pre-heater assembly (damaged or missing o ring).
• Fuel pre-heater switch is off.
Steps to check the air operated fuel valve:
• Disconnect the two transformer wires from the terminal block in the burner.
• Jump the cad cell circuit (refer to page 43).
• Disconnect the fuel supply pump orange wire from the terminal block inside the
burner.
• Set the dial indicator as shown on the diaphragm piston.
• Zero the dial indicator.
• Start the burner so that the air valve opens.
NOTE: The dial indicator should read +.015 to .050, which references the diaphragm piston
travel.
FRONT
REAR
LEFT SIDE
RIGHT SIDE
8" exhaust
View port
Fan Hi-Limit
switch
Clean Out
Access Panel
Blower Moter
Assembly
Electrical Access
Panel
Power Box
Burner
Assembly