Carbon monoxide problem

[bradmbreer]

I have a Yukon Polar - Eagle II furnace which is dual fuel (wood/coal & oil). It was pretty new (maybe 5 years old) when we bought the home we're in now. We've lived here for 3 years and during that time we've only used the oil side of the furnace and never had any problems with CO. This past weekend I decided to try the wood-burning side. I started the fire Saturday morning and we could smell burning wood inside the house although there was no visible smoke. On Sunday afternoon the carbon monoxide detector started going off. I removed the wood from the furnace and opened all the windows to air our the house until the alarm stopped alarming. A week before I started using the wood side I had our furnace repair/cleaning company out to do fall maintenance and they didn't mention any problems. About a month before that we had the chimney cleaners out to do their annual fall cleaning (we also have a wood stove which has a different chimney) and they said all was good with the chimney. The Monday after the CO alarm went off I called our furnace guys and they came by to look at it. The guy checked the heat exchanger for cracks and said he couldn't see any. His only suggestion is to not use the wood side. He admitted he was no wood burning furnace expert but to me his solution was like going to the doctor because it hurts when you lift your arm and the doctor says well don't lift your arm. My neighbor tells me that the previous owner used the wood burning side regularly and the chimney cleaner supports this because he said he came out regularly to clean the chimney for the previous owner as well. I'm not sure how to proceed. I've tried googling to find a wood-burning furnace expert in my area but no luck yet. It seems virtually everyone has oil or gas. Sorry for this post being so long but I wanted to try and provide as much info as possible. Does anyone have any suggestions as to where the problem may be or how I should proceed?

TIA,
Brad

 

[laynes69]

I would suggest removing the firebox baffles and inspecting the main firebox for cracks. I would think though if this was the case the oil side would set off the co2 alarm also. Does the furnace have a barometric damper? If so is it set correctly (-.03" water)? There's a few things that could cause this to happen and that's a blocked flue, weak draft or cracks in the firebox. Maybe discolored areas in the steel or warping could be give away areas. I would start there and see if you find anything.

 

[bradmbreer]

Thanks for responding. The furnace guy did adjust the barometric draft damper. It wasn't closing automatically. Before the CO alarm went off I went down to the cellar to see if I could see a reason why we had a strong smell of burning wood in the house. That flap was open and I could see the smoke was going up the flue. It didn't seem like any was coming out and I didn't know having that open was abby-normal. When the furnace guy came the last time he adjusted it so that it was closes on its own. He didn't indicate to me that he thought that was the issue. Do you think that could have been it? Thanks for the other areas to check.

 

[laynes69]

The purpose of the damper is to open if the draft exceeds a set level. If the barometric damper closes then draft will increase. If you seen the smoke going up and out the flue, sounds as if it's drafting. Did this occur when you first started a fire, or when it occured did you have just coals in the furnace? Sometimes if the chimney is too large under the right conditions the draft can reverse and the house becomes the chimney. What size is your chimney (flue) and how tall? Was the weather warmer when this happened? As the weather outside cools, draft should increase. If your chimney is drafting well, I would look for cracks or even possibly bad gaskets.

 

[laynes69]

The more I think about it, the outer jacket should come off fairly easy. I would remove the skins and examine the furnace just to be safe. I'm not exactly sure how the heat exchanger is laid out, but I would get a strong light and see if it shines through. If the furnace has had creosote in it and moisture gets to it, things can rot out. Basically until it's been examined carefully I wouldn't use the furnace, better safe than sorry. There's been a few threads where their furnaces had been rebuilt a few times due to problems discussed here. You just never know how someone else ran things, especially when it's behind an air jacket.

 

[stee6043]

Here is the bar-none easiest way to find a smoke leak:

Start a fire, let it get burning, turn off all the lights in the room and use small flashlight to comb over the entire boiler.

My bets would be:

1.) A leaking door seal or hinge that needs to be adjusted.
2.) A seam in the chimney leaking. A very small leak can cause a very noticable odor. Sometimes a dab of RTV can make a huge difference.