oil heat exhaust smell/problem

mikesjDecember 12, 2007

I am in need of assistance. I've got a forced air oil furnace in my unused basement. Sometime last spring, I started getting an exhaust smell when the furnace would kick on. It would only last for a few seconds and would come and go- somedays we'd notice it, and somedays nothing. I had the furnace serviced at the end of the heating season and the techs told my wife that it was very dirty.

I started noticing it again this season and again, there's no way to predict it. Sometimes it smells, sometimes it doesn't. It only lasts for the first few seconds that the blower is on. While working in the basement, the furnace kicked on and I saw exhaust blast out of the damper. I checked out the damper and it appeared to be pretty flimsy. I just had a new damper installed- this one is pretty beefy and every now and then I get the exhaust smell.

I turned the thermostat up last night and ran downstairs to check the furnace. There was a puff and exhaust came out of the seams on the vent pipe. These seams are not sealed with anything.

Do I have a major furnace problem here or is the fix as simple as caulking the seams on the vent pipe? If all I have to do is caulk the seams with some high temp silicon, will I be creating too much pressure internally on the furnace?

Thanks in advance for any advice!


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I'm assuming that this vents into a masonry chimney...

Could be a couple of things going on...

First, when was the last time that you had the system inspected and professionally cleaned?

Oil burning appliances should be inspected and cleaned EVERY heating season.

Second, your chimney may not have quite enough draw during certain atmospheric/temperature conditions. That's something that you might be able to discuss with the guy who cleans your chimney.

As for caulking the seams, I can't answer that question.

    Bookmark   December 12, 2007 at 11:34AM
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My furnace vents into a masonry chimney with a 6 inch liner- installed over the summer. It was cleaned/inspected last Spring.

    Bookmark   December 12, 2007 at 12:10PM
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You are describing delayed ignition. The puff of smoke you see is a small internal explosion. When were the electrodes
last set up, filed, or replaced ? Caulking the seams will not help. They do not have to be caulked in the first place. You have to fix the ignition timing in your furnace.
An oil furnace is NOT a D.I.Y. project. Call someone in.
If your service tech does not have at least $2000.00 worth
of test equipment in the truck call someone else. Your
problem could be anything from bad oil, week pump,low pump
pressure,misaligned electrodes,low voltage,partially clogged nozzel,clouded fire eye, or a dozen other things.
One thing for sure there is nothing wrong with your
chimney. One thing, though, caulking the seams will keep
the smoke from the explosion confined to the inside of the
pipe but it will not fix your problem. Good luck.

    Bookmark   December 12, 2007 at 1:37PM
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Thanks for the reply- I was thinking that it was beyond my abilities. I grew up with a woodburner, so I'm happy to leave this one to the professionals.

    Bookmark   December 12, 2007 at 2:16PM
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On occasion we had a problem with our oil furnace smelling and discovered our basement filling with blueish smoke. Turns out that when we use our OLD and POWERFUL extractor fans in our bathroom and/or kitchen it does something to our furnace if it is running! We have since learned to turn it off or make sure it's not running before to use our extractor fans. Also, only on a couple of occasions, we had the same problem when we made a fire in our fireplace. Strangely that doesn't always happen.

Now we are wanting to update our kitchen and bathroom with new extractor fans and we are wondering how to pick new ones. Do any of you oil furnace experts have any suggestions on what extractor fan power strength might be best to keep our furnace from smoking? Thanks.

    Bookmark   April 3, 2008 at 12:22PM
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