Gas and Oil Home Heating Furnaces - Gas Furnace keeps turning off, blowing cold air....

I've got a huge problem. It's freezing outside and I don't have any heat. We went to bed with heat, woke up without heat. I initially thought it was the thermostat so I replaced it with a new one. It didn't seem to fix the problem. I also replaced the filter. I've read through a lot of posts and the suggestion I keep seeing is to sand the flame sensor. I'd be more than happy to do that but I can't seem to find it on my unit.

Problem: furnace starts up and will blow cold air for about 5 minutes and then shut off. it won't come on again unless I hit the reset button. the furnace will start up but only blow cold air for another 5 minutes or so before shutting off. making things worse, the furnace is up in the attic so i've constantly have to go up a ladder.

Furnace: Gas Rheem Criterion. It states it has auto ignite so you don't have to manually turn on the pilot.
Age: ~7 years.

Here are some pictures:

<img src="http://teachers.henrico.k12.va.us/pocahontas/mandzak_b/DSCN2723.jpg"/> <img src="http://teachers.henrico.k12.va.us/pocahontas/mandzak_b/DSCN2724.jpg"/> <img src="http://teachers.henrico.k12.va.us/pocahontas/mandzak_b/DSCN2725.jpg"/>

I think I would probably start with hot surface igniter (HSI). Do you know how to unplug the HSI and do a continuity check?

Is the reset button you are pushing the one pictured under the copper gas line & near the gas valve? If it is, DO NOT CONTINUE TO PUSH IT. This is a flame roll out switch & a safety device. Get a service person to look at this furnace NOW.

:alarm:
Yes I agree with Grady.
That is the only reset button on the furnace.
This trips when there is a crack in the heat exchanger. A crack in this can put carbon monoxide into the house and KILL you.

I agree, if you are pressing the flame roll out button, call for service.


BTW, How did you post pictures on here!???

Thanks for everyone's reply. I really appreciate your feedback. I had a friend who works on commercial systems come by and take a look. We pulled the ignitor out and realized it had short circuited. Bear with me I'm not up with all the correct terminilogy. He was able to fire up the furnace using a match but I was told it would only run for that particular cycle. i'm going to order the part tomorrow. hopefully it'll be here sooner than later but we've got space heaters for the time being. By the way, the thing that I referred to as the reset button is just the door safety switch to make sure the fan stays off while the front panel is off.

here's a pic of the part (To post pictures: [img src="location of image file"/] replace [ ] with < >):

<img src="http://teachers.henrico.k12.va.us/pocahontas/mandzak_b/DSCN2728.jpg"/>

You scared us there. I'm glad it was the door switch & not the flame roll out you were pushing.

Thanks for the update.

One thing came to my mind here.... Is there a trap in the gas line???

I'm not sure what you mean by trap. I'm a complete newbie when it comes to many home repairs. :)

As long as we are on the subject of the gas line: My advice is to call a pro & have that copper removed & replaced with black steel pipe. After seeing all of the black flakes in a gas line I replaced last week I was astonished that the furnace still worked. Copper can flake off & get caught under the seat of the gas valve causing it not to seat & gas to leak thru.