Oil burner chimney problems-need advice

[Badfish740]

All the more reason to get cracking on installing central wood heat! Anyway, sitting in the living room I noticed a strong smell of fuel oil and went down to the basement to investigate. Once I turned the lights on I noticed a very fine haze hanging in the air. This is probably only the second time we've used the heat this year, and we just bought the house in June. I called the company that had installed the unit and the guy came out and quickly determined that the chimney was not drafting properly. We were able to get it to draft by holding the butterfly at the base closed and running the furnace. At first with the draft open just a bit, hot gases were blowing out forcefully into the basement. Also, when the tech pulled the pipe from the wall there was quite a bit of loose soot in the bottom. Once we forced the butterfly closed the chimney began to draft. However, he recommended we get a chimney company out to take a look. From all outward appearances the chimney looks fine. It's a masonry chimney (12" x 12" block) with an intact parge coat and cap/screen. I'm going to try to get up on the roof tomorrow to take a closer look at the cap to see if there are any breaks in it where a bird could have gotten inside or something of that nature. I also thought about putting a mirror at the base of the chimney and then shining a flashlight from the top to see if I can find any problems-what should I be looking for? The tech guessed that a tile could have come loose inside and was obstructing airflow-if this is the case would I be looking at relining? How much does something like that usually cost? Would there be any reason I would need an entirely new chimney? If so, is there anything I should keep in mind for the new one given that I would like to install an add-on wood furnace soon?

Thanks!

 

[homebrewz]

It sounds like the chimney needs to be cleaned. Better have it done.. especially if it was so bad
the exhaust was a fine mist in the basement! The components in the exhaust, volatile organic
compounds, and whatever else will over time eat away at the clay liner in traditional chimneys.
If you are planning on keeping the existing setup, you could reline the interior of the chimney
with a stainless steel flexible liner, providing that the rest of the chimney is structurally sound.

Oh, and get a CO (carbon monoxide) detector. Please.

 

[Badfish740]

It sounds like the chimney needs to be cleaned. Better have it done.. especially if it was so bad
the exhaust was a fine mist in the basement!

If a simple cleaning was all that was needed I wouldn't have been that concerned, but the guy that came out felt that it was probably more serious than that.

If you are planning on keeping the existing setup, you could reline the interior of the chimney
with a stainless steel flexible liner, providing that the rest of the chimney is structurally sound.

As stated, it looks sound, no cracks in the parge coat, leaning, etc...but only a close inspection will tell. Provided that I don't need an entirely new chimney how much does the stainless steel liner typically run? How is it sold-by the foot? Is it sold at the big box stores so that I can look and get an idea of material cost?

Oh, and get a CO (carbon monoxide) detector. Please.

Got two of 'em.

*EDIT*

I posted this question on another forum and got a response that made me think of something I hadn't mentioned. We began the buying process on this house in May and around early June a new roof was put on along with two large roof fans due to a moisture problem in the attic. The fans are each controlled by a thermostat and a humidistat. I notice that even in the cold weather they run quite a bit due to the fact that they are also triggered by high humidity. Could these two fans running be causing a vacuum in the house? The house is nearly 50 years old and I wouldn't call it "airtight" but it's not drafty either. The previous owner also installed new windows before we moved in, so they're reasonably tight. Now that the weather has been cooler we've been keeping the windows closed but not turning on the heat. The other day I got out of the shower and the bathroom fan wasn't doing a good job with the steam so I opened the window. I immediately got a steady blast of cool air despite the fact that things were completely still outside-was this the fans sucking air out of the house? Since the fans/windows were installed over the summer after the previous owner was done using the heat for the year that would explain why we are having problems. Maybe I should try disabling the fans, running the furnace, and seeing if I get the same problem?

Of course, let's say that this does turn out to be the problem-then what do I do? I don't want to just turn off the fans because I'll end up with a warm house and a moldy attic. My home inspector told me that the moisture problem was caused by undersized gable vents and that the addition of a ridge vent and two roof fans would take care of the moisture. Of course we didn't anticipate this. One thing I've always thought was weird about the house is that the soffits are completely solid-no vent panels anywhere. Would it help to install those little press-fit vents in there? I'd really like to avoid having to enlarge the gable vents if at all possible. What else can I do to keep the fans from sucking all the air out of the house?

 

[homebrewz]

As stated, it looks sound, no cracks in the parge coat, leaning, etc...but only a close inspection will tell. Provided that I don't need an entirely new chimney how much does the stainless steel liner typically run? How is it sold-by the foot? Is it sold at the big box stores so that I can look and get an idea of material cost?

Right, the outside looks sound. How about the inside? Try the mirror idea.. that's what I see my furnace guy use.
I only mention a proper cleaning, because I had a similar problem a few years ago, and a good cleaning took care of it.
My furnace guy took out about a cubic foot of crud, including some small pieces of clay flue tile (yikes).

I bought 30' of stainless flex liner for around $650-$700 a few years ago. I don't know what prices are currently.
Hopefully others more knowledgeable about such things can fill you in.

Not sure about the house fans. Maybe you could hang something to indicate air flow movement at different points
in the house/basement to see if that's part of the cause? Or maybe just cut power to the fans for a day while the
furnace is running?

 

[Badfish740]

If only all fixes in life were this easy! I did the "toilet paper test" at each window (open about 1") with the roof fans running and the strips would float nearly parallel to the floor. After going up to the attic to turn off the roof fans I repeated the test. This time at each window the strips hung vertically and did not move a bit. I went downstairs, fired up the oil burner, and repeated the test once again near the butterfly valve on the flue-the updraft nearly sucked the paper out of my hand and up the chimney. I guess it just goes to show how powerful negative pressure can be-my roof fans (there are two) are only about 10" in diameter! Anyway, the long term solution will be to install soffit vents-much better than relining a chimney! I'm still going to get the chimney swept/burner serviced though. I'd like to get everything tuned up before I hopefully put the oil burner into mothballs for emergency use only

 

[Gooserider]

Sounds like you have more of a root problem than just the fans. Definitely putting more venting in the attic should help, but it doesn't seem good to me that the fans are having that easy a time of it to depressure the rest of your house... I'd look to see what sort of air leaks you might have between the living space and the attic, and seal those up... That is also probably a good part of where your attic moisture problem is coming from - typically the air in an attic should be about the same humidity as the outside air. If you are getting high attic humidity, it must be coming from somewhere, like the inside of your house... This is a sign of air leakage, and energy wasting in a big way...

Gooserider