Greetings all,
I have a Heil furnace that has a problem. I was hoping that someone here could help me out.
The problem is the igniter sparks and lights the pilot and then the pilot goes out right away. I spoke w/ a friend who is a HVAC tech and he told me that it was most likely the flame sensor. Ok so I took the unit apart and removed the igniter assy looking for a flame sensor. I couldn't find one. The closest I can figure is that the igniter and flame sensor are one and the same.
After I took the whole assembly out and cleaned it up per my friend's instructions, it still didn't work. I used a fine emery cloth and followed up by spraying the assembly w/ Zep Elec contact cleaner to make sure I flushed away any particles I may have created by sanding.
Tonight I turned the igniter 90 degrees in it's mount and voila, the pilot stayed on for more than a second and the burners fired up.
The igniter unit has what appears to be a high tension lead going from the end of it to a box made by Honeywell. There is also a grey ground wire coming from the unit's mounting bracket that goes to the "ground" terminal on the same box. That doesn't really make sense as the furnace should be grounded anyway but that may there just for redundancy.
The furnace was installed in 1992 or 1993. I don't know the exact model of the furnace but in doing some research, I found a picture of the igniter assembly online. It can be viewed here:
The only way I can figure is that the Honeywell box sends out a high voltage to the unit in order to fire the spark, and then waits for a signal coming back on the same line telling the microprocessor that the flame is present and it is okay to fire the secondary part of the gas valve. The valve has three wires going to it and I figure that it must be a two stage valve that fires the pilot at the first stage and the burners at the second.
My questions is this. Is there any way other than just swapping parts to determine whether it is the igniter/flame sensor assembly or the Honeywell box causing me grief?
Any answers would be greatly appreciated.
Thanks in advance,
EBB