On Sat, 29 Dec 2007 20:32:26 -0800 (PST), hvacrmedic
wrote:

On Dec 28, 3:00*pm, wrote:
My gas furnace seems to be working well. It heats when it should and
shuts off when it should. The trouble is that the igniter clicks all
the time. This happens whether or not the gas is on. Any suggestions
as to what is happening would be greatly appreciated.

Thanks
Mark

It depends upon the model of the furnace. Some older furnaces use a
stand alone ignition module that uses the ignitor probe to sense the
pilot flame. If the sensor is oxidized, or the module is defective or
not grounded well, then the ignitor will never stop sparking, whether
or not a pilot flame is present. The gas valve on this system senses
the pilot independently via a thermocouple mounted in the pilot burner
assembly. Because the valve has a different pilot flame sensor it will
go ahead and operate normally even when the ignitor fails to sense the
pilot flame.

If this is the type of system that you have, then there is no danger
in running it, but IF IT ISN"T, then you have a potentially serious
issue with a control board or control circuit. The furnace could
literally level the structure to the ground if the main valve is
opening without a pilot established first. Best to have it checked by
a qualified technician.

try cleaning the thermocouple, or replacing it. The control board
cannot sense is not getting enough voltage and therefore, always
trying to light the pilot.

Are you sure it is the ignitor clicking, and not the main gas valve
trying to turn on? That sounds like a click also.
My funace, the ignitor is more of a 'tick' in rapid succession, to
light the pilot. When it calls for main gas valve, I can hear a
'click' for the main gas valve.

samurai.