20
Cad Cell
Check cad cell with ohmmeter. If
more than 2000 ohms, cad cell is
defective or dirty.
Primary
After burner fires, open cad cell
Control
circuit if flame looks OK. If
burner continues to operate, fault
is in primary control.
Heat
Inspect heat exchanger.
Exchanger
Restriction
Burner
Burner motor trips on overload.
Motor
Turn off power and rotate blower
by hand to check for excessive
drag.
Faulty or dirty cad cell
Faulty primary control
Plugged heat exchanger.
Line voltage below 102V
Faulty motor.
Pump or blower overloading
motor.
Clean or replace cad cell.
Replace primary control.
Clean out heat exchanger.
Call utility company.
Replace motor.
Replace blower or pump.
SOURCE
PROCEDURE
CAUSES
REMEDY
TROUBLE: BURNER FIRES, BUT THEN FAILS ON SAFETY
Circulator
Check to see if operating control
is working properly.
Thermostat
Check thermostat settings and
calibration.
Flow Valve
Check to see if flow valve is
operating properly.
Circulator does not stop
running.
Thermostat set too high.
Thermostat defective
Thermostat out of calibration.
Flow valve dirty and stuck.
Flow valve defective.
Repair operating control.
Reset thermostat.
Replace thermostat.
Recalibrate. Check level.
Clean flow valve.
Replace flow valve.
SOURCE
PROCEDURE
CAUSES
REMEDY
TROUBLE: TOO MUCH HEAT
When checking burner adjustments always use instruments.
