PROBLEM
PROBABLE CAUSE
Electric Heater
Electrical or Mechanical
Disconnect switch or main circuit breaker may be
Not Operating
in the "OFF" position. If heater has built-in disconnect
switch, door must be closed and switch turned "ON"
before heater will operate
If the fan and heater are interlocked with a fan relay, the
fan must be on before the heater will operate. If an air
flow switch is used, air pressure in the duct must be
sufficient (at least 0.7" W.C.) to close the switch
before the heater will operate
Automatic (or manual) reset thermal cutout may have
opened when overheating resulted from insufficient air
flow or poor air distribution. Allow heater temperature
to return to normal so that automatic thermal cutout
may reset or manual reset thermal cutout may be reset.
Correct cause of overheating before proceeding.
Heat limiter(s) may have opened if local "hot spot"
developed or if automatic reset thermal cutout failed to
open first, when overheating occurred. Correct cause
of overheating and replace heat limiter.
Check main fuses, if open, correct cause of failure
before replacing fuses.
Electric Heater Cycles
Electrical or Mechanical
Check air inlet and discharge openings for obstructions.
(Will Not Stay On)
See that filters are not clogged, fire dampers are open
and air system is balanced
Check to see that the heater terminal box is tight
against duct and heater safety devices are receiving
sufficient air flow. Air flow must be distributed evenly
over entire face area.
Look at heater coils in operation (through observation
port in duct); any red area is not receiving enough air.
(A small amount of redness is permissible inside the coil
insulation bushings). Make sure that air flow through
every part of the heater is sufficient.
Coils must not glow.
If air flow switch is used, contactors may "chatter" if air
flow is not sufficient to keep switch fully on.
If duct has internal insulation, the insulation may be
blocking the safety devices.
Improper Temperature
Electrical or Mechanical
Make sure associated control equipment, such as
SOLUTION
TROUBLE SHOOTING GUIDES
ELECTRIC HEATING COILS
