PAGE 24 of 61 HO-7-1237 & HO-4-1234 OIL-FIRED HEATERS
© SAMUEL JACKSON, INCORPORATED 2003 ALL RIGHTS RESERVED
The modulating motor (MM) on the fuel valve at the burner head can now be tested and
the Low Fire Switch (LFS) adjusted. In addition, this step tests the electronic drive (ED)
for the motor. Turning the +/- selector switch to the “+” position applies 20 mA DC to
the drive, which should open the drive to the high fire position. Releasing the switch will
freeze its motion permitting adjustment to the linkage. Turning it to stop removes the DC
current from the drive, which should bring it to the low fire position. As the valve
approaches the low fire position, observe light for Input No. 24 to make sure that it turns
on only at the low fire position.
The operation of the Low Fire Switch LFS is checked by the PLC during the pre-burn
routine. The PLC will not permit the burner to start unless LFS operates properly. Adjust
the switch by rotating its cam on the shaft. Starting with the fuel valve in the extreme low
fire position, the Low Fire Switch is adjusted properly when Input 24 goes off after
holding the +/- selector switch in the “+” position for 6 seconds.
Press RESET to proceed.
STEP 7
-- The fuel pump and combustion air fan are started at this step. Verify that both
motors are turning in the proper direction (indicated by the arrows on the motors). If not,
kill power and reverse two of the leads at the proper motor starter. Return to this step in
the test program.
If this is a new installation, it will be necessary to purge the fuel line. Open the cock at
the burner head and place a container beneath the clear plastic tube coming from the
cock. Turn the start-stop selector switch at the burner control panel to the start position
(
l
). This will open the Fuel Oil Valve FOV in the lower cabinet. Turn the +/- selector
switch to the “+” position to begin opening the fuel valve at the burner head. Releasing
the switch freezes the fuel valve position and “-“ position closes the valve. Avoid
opening the fuel valve too far as some fuel may wet the ignitor plug making burner hard
to light. Watch the fuel rise in the flowmeter FF, and spill into the container. When it
becomes clear with no air bubbles, tur n the start-stop selector switch to the stop position
(
O
), then close the cock.
The oil pressure should be steady. Observe the oil pressure, which normally should be 60
psi. This pressure determines the maximum heat output of the burner. If necessary,
adjust the pressure with the Fuel Pressure Relief Valve FPR in the lower cabinet. FPR
has an adjusting screw under its cap.
The Oil Low Pressure Switch OLP (left) should turn OFF Input 20 when the pressure
falls below 45 psi (3.1 bars). Adjust OLP if necessary. The Oil High Pressure Switch
OHP (right) is factory set to turn OFF Input No. 21 at about 90 psi (6.2 bars).
Press RESET to proceed.
