I read through tons of questions related to this... sorry for a repeat. I went to turn on the heat for the 1st time this season, wouldn't start--i heard it try to kick in from upstairs(it's in the basement), but nothing.. I opened the cover to check the pilot, etc, and found a dead bat in the furnace (burner section)! Pilot was out. Cleaned yhe furnace, put in new filter. I tried relighting it. Nothing. I changed the thermocouple--after fighting to get it out (someone used a round screw-hard to access at a 90). Tried to relight--nothing. I thought maybe the thermo wasn't long enough (no coil of excess) so I bought a 2nd, changed it and still won't light, flame is great while holding it (nice blue shade-hits the top 3/4 inch of the thermo). I have had the gas valve changed 2's since 2005! I find it hard to believe yet another can be bad. I did notice the board the thermostat wires go to is warm (including a black block looking thing behind the small board). I also hear a very low hum. What can it be--is there a limit switch that would be keeping the pilot from staying lit? The blower motor is also newer (2008-or9)... it is a honeywell gas valve (universal) and an armstrong furnace about 25-30 years old. I can add a pic if necessary. Thanks for any ideas of what to try before I have another gas valve installed.

More info---looking through the sticky notes the part that is warm is the fan center. I am going to keep reading all I can here as well.

We are getting cold here--i have found the 2 limit switches that both have 2 wires. Both also have what looks like buttons popped up. Nothing on the sticky notes shows these have a button of any sort. If the bat shorted one when it got in the furnace, would this keep the gas valve from opening and keeping the pilot lit? I appreciate any help---can't afford a tech to come in

http://www.facebook.com/media/set/?set=a.10150093709319138.275832.534334137&type=3#!/photo.php?fbid=10150366904284138&set=a.10150093709319138.275832.534334137&type=1&theaterhere is one of 2---they look very similair-the second one has a white top on the button

http://www.facebook.com/media/set/?set=a.10150093709319138.275832.534334137&type=3#!/photo.php?fbid=10150366904284138&set=a.10150093709319138.275832.534334137&type=1&theater see if this works

I will get this figured out---not sure of these pages are active--changing gas valve.