What is this pile of black ash in my furnace? I don't smell gas - can I re-light it?

January 2, 2011 10:23 AM

What is this pile of black ash in my furnace? I don't smell gas - can I re-light it?

I'm in Canada. The pilot light on my furnace went out over night. This has happened before and as a good Canadian I know how to safely light a furnace pilot light. BUT: There is a small pile of black ash under where the pilot light is and I don't remember ever seeing this before. Also, the, uh, tube/cover thing (it's like a flexible, high-density, web-like fabric) looks black and gray (used to be white) -- but maybe that's something that happens over time. IMPORTANT-- I DO NOT smell gas at all and have followed the instructions for turning off the electrical and setting the pilot to the off position. What is this ash pile? Is it normal and just means that the furnace needs an adjustment or has there been a small fire in there? Thanks,

posted by Toto_tot to Home & Garden (4 answers total)

It could be an indication of a crack or leak. The pilot could be burning "dirty" or incomplete. You'll definitely want to have a professional check it out with a combustion analyzer, as well as examine your exhaust and CO ppm.
posted by samsara at 11:03 AM on January 2, 2011

I just had this happen at my Mom's house last week. It didn't stay lighted and had a bit grey-black ash-looking residue (but only a little and I couldn't tell if it was just incinerated dust or what).

It turned out that there is a crack inside that forced the safety valve to shut off the gas when the crack let too much heat get through. The guy who came to check on it didn't say anything about the residue, though.
posted by Tchad at 11:24 AM on January 2, 2011

happened to my stove...forget what the exact issue was, but i do remember i called the gas company and they sent someone out to fix it for free the same day...
posted by sexyrobot at 12:08 PM on January 2, 2011

That means, to me, that the pilot was burning incompletely. Too much gas for not enough air. When you light it, see if it burns nice and blue, or if it is burning orange. Look for an air orifice on the tube of the pilot that might be blocked.

I've never seen one of those web looking ones, I'm guessing it is like a gas mantle? They eventually fail- maybe that's all it is?
posted by gjc at 3:52 PM on January 2, 2011