34
I-OH (01-20) PN120390R7
MAINTENANCE—CONTINUED
Troubleshooting—Continued
Primary Control Troubleshooting
Determine the malfunction that caused the primary control to activate as follows:
1. Disconnect the nozzle line connector tube and reposition it so that oil goes into a container. Tighten the flare nut
at the pump discharge fitting.
2. Reset the primary control safety switch and immediately be alert to watch and listen for the following:
a.
Contact action of primary control relay:
relay should pull in promptly without arcing erratically or chattering.
If relay does not function properly, proceed to step 4.
b.
Quality of oil delivery:
oil stream should be immediate, clear, and steady. A white, frothy oil delivery indicates
air in the supply system. No oil delivery indicates a severe restriction.
c.
Ignition arc:
when the ignition activates, you should hear a buzz. If the ignition does not activate, check the
transformer and electrodes.
d.
Motor operating characteristics:
the motor should start quickly and smoothly. You can hear the RPM change
and a click as the centrifugal switch disconnects the start (auxiliary) winding.
3. If the malfunction has not been revealed, reconnect the nozzle line fittings and prepare for a fire test. Be sure to
check the combustion chamber and remove any accumulation of unburned oil.
a. Reset the primary control, if necessary, and observe the overall performance with concentration on the light-
off. Run several cycles.
b. Observe the flame quality using a flame mirror, if possible. Flame base should be stable and close to the
combustion head. Flame should be centered, uniform in shape and relatively quiet in operation.
c. Check the heat and combustion chamber for carbon or impingements that indicate a defective or partially
clogged nozzle.
4. If the problem is not apparent, check the primary control system.
a. Measure the electrical voltage at the primary input (usually black) and neutral lead (usually white) connections.
b. Jumper the thermostat (TT terminals) or otherwise energize the primary control.
c. The control relay should pull in. If not, make sure that the wiring connections are secure. If wiring connections
are secure, check that the cad cell that controls the safety lockout timing on ignition is not seeing too much
stray light.
(1) Check the cad cell by starting the burner and disconnecting both cad cell leads from the control FF terminals.
(2) Jumper the FF terminals to keep the burner operating. Measure the ohms resistance across the cad cell
leads as it views the flame. This should be 1600 ohms or less. A preferred reading is 300-1000 ohms.
(3) Next, with the meter still connected to the cad cell leads, turn the burner off. The dark condition should give
a reading of 20,000 ohms or infinity. If the reading is lower, let the refractory cool down or look for stray
light that might be entering the burner through the air inlet, or around the transformer baseplate.
(4) If the cad cell is not performing within these guidelines, replace it.
(5) If the wiring connections are secure and the safety lock timing and cad cell are functioning properly, replace
the primary control.
d. If the primary control relay pulls in and then locks out again quickly, check the safety lockout timing. The safety
lockout timing can be checked by removing one of the F (cad cell) leads from the control. Count the seconds
until the control locks out. The time should be close to the rating plate specification found on the control body.
e. If the primary control relay pulls in erratically and chatters, check the wiring connections and verify that the
heat anticipator setting of the thermostat matches the 24V current draw. Erratic operation can sometimes
be traced to improper anticipator settings of the primary control. These settings are typically 0.2 or 0.4 amps
(printed on the side of the control). Measure this value by connecting your multi-tester in series with one of
the TT lead and reading the value of the appropriate milliampere scale. If the wiring connections are secure
and the anticipator settings are correct, replace the primary control.
f. If the primary control relay pulls in, but the motor fails to start, measure the voltage between the neutral lead
and the primary control lead for the motor. A severe voltage drop here would indicate that the relay switch
contacts are defective. Replace the primary control.
