Model DP Oil-Fired Heater
Page 15
1.
Is there power to the heater? Have you checked
the reset buttons on the motor and primary
control?
2.
Place a jumper wire across the two terminals on
the cad cell. If the burner starts, the problem is in
the heater control circuit. This circuit consists of
the pressure switch, high limit control, safety
switch, thermostat, time clock switch (if one is
installed) or the wire harness. Check the wire
harness for any loose wires or worn insulation.
Then jumper each control until the problem is
located.
3.
Press the reset button on the primary control. If
the unit does not start, go to step 5. If the unit
starts, turn off the power and check the following
items that can lock out the primary control:
a.
Dirty or defective cad cell (see Page 4).
b.
Defective primary control (see Page 4).
c.
Oil level in tank too low or water in the
tank.
d.
Poor combustion caused by:
Fouled nozzle
Fuel line air leaks
Improper nozzle pressure (pressure should
be 100 psi)
Improper air setting (see part D)
4.
Press the reset button on the motor. If the unit
does not start, go to step 5. If the unit starts, shut
off power and check the blower wheel and
flexible coupling between the motor and the fuel
pump. Make sure the blower wheel and fuel unit
are not binding. Make sure the return fuel line is
not restricted.
5.
Remove one cad cell wire from the primary
control. If the burner starts, replace the cad cell.
6.
Turn off electric power to the heater. Short out
the high limit switch, in the high voltage circuit.
If the burner starts when power is restored, the
switch is faulty.
7.
Turn off electric power and inspect the wiring
below the primary control and the ignition
transformer. Make sure there are no loose
connections.
8.
If the wiring is okay, and the blower wheel
rotates freely, replace the primary control.
4E-2. Burner Tries to Start, but the
Primary Control 10 Shuts Off
(either motor or transformer or
both come on)
1.
Is the burner motor turning? If yes, go to next
step.
2.
Press the reset buttons on the motor and primary
control. If the motor does not start, but
transformer is providing spark at the electrodes,
go to step 3.
3.
Lift the ignition transformer and make sure the
motor rotates freely. If it does not rotate freely,
replace the motor. If the motor is internally
binding, replace the motor.
4.
Open the inspection port and use a mirror to
check combustion. If there is no ignition before
the primary control shuts the burner down, go to
step 6. If the burner does ignite with a good
flame, go to step 5. If the burner tries to ignite,
but the flame is intermittent, go to step 8.
5.
Check the cad cell and primary control.
6.
Lift up the ignition transformer and put tape over
the front of the cad cell (the burner will not start
unless the cad cell senses no light). Disconnect
the black lead going to the motor. Press the
primary control reset button. Use an insulated
screwdriver to touch the metal blade to one spring
contact on the transformer, and about 3/8" away
from the other spring contact. If there is good
spark between the blade and the spring, go to the
next step. If there is no spark, replace the
transformer.
7.
Remove the electrode-nozzle assembly and
inspect the high voltage sections for fouling,
cracked insulators or burnt electrodes. Replace
any defective parts.
8.
If the flame is poor quality or intermittent, use a
pressure gauge to check the nozzle pressure. If
the pressure is below 100 psi, but steady, reset it
to 100 psi and go to step 9. If the pressure is not
steady, use the attached Sundstrand Field Service
bulletin to check out the fuel unit. An unsteady
pressure reading could be a sign of a dirty oil
filter.
9.
Replace the burner nozzle with the nozzle called
out on the heater rating plate and go to step 10.
Replace nozzles once a year as part of the annual
cleaning and inspection service.
10.
Check the C0
2
Of the flue gases. The reading
should be between 11.5 to 12.5%. If the reading
is different, go to Section D.
4E-3. Oil Burner Will Not Shut Off
Remove one of the thermostat leads from the
primary control. If the oil burner shuts off, the problem
is in the heater control circuit. The circuit includes the
pressure switch, high limit safety switch, thermostat
and wire harness. Check for worn insulation on the
wire harness, which could cause a short. Check
operation of the thermostat and pressure switch.
4E-4. Setting the Correct Fuel-Air Mixture
