Disabling The Air Operated Fuel Valve; Vacuum Gauge Reading Hints - Lanair MX SERIES 250 Installation And Operating Instructions Manual

Install a jumper wire between the two F-F
terminals. Be careful not to touch the T-T
terminals as it may damage the control.
Push reset button for 2 seconds.
Turn room thermostat up so that it calls for
heat.
Disable the air operated fuel valve.
To activate the oil primary momentarily dis
connect one end of the jumper wire on the
F-F terminals. The burner will attempt to fire.
IMPORTANT remove the jumper wire when
testing is complete, and replace the cad cell
wires. Do not run the heater with the cad cell
wires disconnected.

Disabling the air operated fuel valve.

Note: Most trouble shooting tests will require the air operated fuel valve to be disabled, to
do this:
Adjust the heater air filter/regulator to -0- PSI.

Vacuum Gauge reading hints:

No reading 0-1 HG
Pump not operating.
Pump air locked and needs priming. Refer to section 10.
Vacuum leak: ✓ Pump shaft seal
✓ Suction strainer gaskets
✓ Pipe connections suction side
Low to normal reading, 1-6 inches HG.
Pump operating properly.
Fuel oil is being used.
High level of gasoline in the fuel (use approved fuels only).
High reading, 7 inches of HG, or more.
Fuel being used has to high of a viscosity.
u F l e s i o t o o c . d l
Fuel contains gear lubes (use approved fuels only).
Reading fluctuates (jumps).
Vacuum leaks in the suction side of the piping to the pump.
Low fuel level in the tank.
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45
Section 14 - Troubleshooting
Install jumper wire
✓ Pump cover gasket
✓ Low fuel level in tank
✓ Strainer in pump cover
Fuel being used has a low viscosity.
Fuel is at room temperature (warm).
Suction line strainer dirty or plugged.
C h e k c a v v l i e s n a t e l l d w o r n g r o t s c u . k