Lanair HI140i - Manual (Page 52)

SECTION 17 CONTINUED
4. Reading drops to –0- PSI when the burner is off.
a. Dirt between the diaphragm and the seat in the by-pass regulator.
b. Dirt between the plunger and the nozzle seat.
c. Leak in the plumbing connections.
d. Leak in the preheater assembly (damaged or missing o ring).
e. Fuel preheater switch is off.
17.9 Steps to check the air operated fuel valve:
1. Disconnect the two transformer wires from the terminal block in the burner. Jump
the cad cell circuit, refer to Section 17 (17.2).
2. Disconnect the fuel supply pump orange wire from the terminal block inside the
burner.
3. Set the dial indicator as shown on the diaphragm piston.
4. Zero the dial indicator.
5. Start the burner so that the air valve opens.
6. Note the dial indicator, it should read +.015 to .050, which references the
diaphragm piston travel.
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