Follow up on my stinky flu/fireplace

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StinkyFlueStu

Member
Apr 28, 2016
32
Missouri
Hi! Back in April, I started a thread about my stinky flue. I got some very helpful people responding, but it became clear that I had left some info out, plus pics were requested. I meant to just update that thread, but I got sidelined due to multiple family emergencies. So, here's a brand new thread, where I'm hoping the experts here can help me finally resolve this.

Feel free to read the original thread for details, here. Otherwise, here's a brief summary. We bought the house about a year ago. At the time we had multiple sweeps inspect the chimney. We had a crack in the mortar cap sealed, sealant sprayed on the brick, and we removed a gas line that a previous owner had used to put a gas display inside the fireplace. Also, before we ever even burned, we had a radon fan installed under the foundation.

During our first winter of burning, we didn't have much trouble. The wood we bought was wet because we bought it during a storm and it had been stored outside. Winter was wet and cold, so it never really dried off. We'd get some smoke coming in from the fireplace while starting a new fire, but once the fire was hot enough, no trouble. We would then dry off the next few logs next to the fire, and again, no trouble. We also had some smoke come out of the blower vents, but this stopped when we stuffed insulation into the gap between the front edge of the metal firebox liner (one guy called it a "heatilator?") and the front brick wall of the fireplace. Oh, and we had some smoke get sucked into the basement during the first burn, because there is a second chimney that goes down to the basement, but the wood stove was removed long before we moved in. We sealed up the holes in the wall and that has never been an issue again. Both chimneys have rain caps.

In January, we stopped burning and had a sweep clean the chimney. He said it was pretty clean to begin with. He looked at our wood, because I was nervous about how wet it was. He said he agreed it was seasoned fine but just got wet from being outside before we bought it.

Throughout January, we occasionally got smell from the fireplace. I tried taping aluminum foil across the entire fireplace door. That helped with the smell, but it made so much noise from getting sucked in and out by the air coming in/out through the drafty damper, that we couldn't stand it. So, I taped aluminum foil across the top of the flue and plugged the bottom with a homemade chimney "balloon" (trash bag stuffed with insulation). I also vacuumed every speck of ash that I could out of the firebox, plus I found a TON of ash/loose gunk in the smoke shelf that the sweep had supposedly "cleaned." No problems with smell again until mid-April.

In mid-February, we had weatherization work done on the house. This included additional attic insulation, caulking the windows, door sweeps, etc., plus a small, always-on exhaust fan in the basement. We still didn't have any problems until a month after this work was done.

Finally, in mid-April, we woke up to the house smelling like "Satan's butt-hole." It was just the thickest, stankiest, nastiest fireplace smell I've ever encountered. We tried all the troubleshooting we found online, but we couldn't get it to change by cracking windows, turning appliances off/on, etc. We called some sweeps.

The first sweep first blamed it all on our flue being too short, causing the prevailing wind to come across our roof and straight down the flu. I pointed out that the flue had been completely sealed with the foil, so he changed his mind and said that he could see water literally trickling down inside of the flu. He also said he could see efflorescence in there. He showed me a picture (attached), but I didn't see any of what he was describing. He also said that mortar chimney caps are absolutely not acceptable and that I would need a steel cap immediately.

The next two sweeps disagreed with almost everything the first guy said. They said that the mortar cap could be replaced if I wanted, but that it looked like the crack had been repaired just fine. They said that there is always some dampness that soaks in through the bricks/tiles, and that I had caused this to build up and compound by sealing both ends of the flu. One recommended either an insert or at least an airtight door, while the other said to just put kitty litter in there to soak up the smell (which didn't help at all). A fourth sweep couldn't come out, but he talked a lot over the phone and basically agreed that I messed up by plugging the flue completely, and he recommended an insert. All the sweeps said that there is no magic bullet, as there's nothing obviously wrong with the chimney, other than my stupid sealing method. Oh, and one guy said the ash dump, which has been plugged with decades of compacted ash since we moved in, needs to be cleaned out and bricked off, but the others said there's no way it could be making any smell.

I also talked to weatherization people, HVAC people, etc. They all agreed that the radon fan and the exhaust fan create such a tiny amount of suction that there's no way they could be responsible for this (plus I know the radon fan was running the entire year before this started). They also said that my house isn't tight enough to warrant an air exchange and that it couldn't help with this. This was told to me after the final inspection and blower door test, so I feel like they must know what they're talking about. This doesn't mean there isn't a draft issue (there obviously is), but I take them at their word that an exchange and/or removing the fans won't fix it. Edit: Also, I tried turning the exhausts off for over a month, and it made no difference at all.

While going through the first thread discussion, I found that if I burned candles in the fireplace, the smell almost completely disappeared (but only while burning). As the days got hotter and more humid (I'm in the Midwest), I would have to burn more and more candles. Finally, the chimney balloon I ordered arrived. It has definitely helped reduce the smell, but the smell is still there. It's worse than when I had candles burning, but still a tiny fraction of what we originally encountered. Edit: I've also noticed that the smell still fluctuates drastically based on the weather. Hotter and more humid days result in a thicker smell that radiates further from the fireplace, while cooler, dryer days result in very little odor.

So, now my plan is to either get an insert+SS liner, or to get a Lyemance top-damper, airtight fireplace door, and gas loglighter.

I'm leaning toward the insert+liner. However, I worry that because we still never identified the one "thing" that is wrong with the flu, I'll spend thousands of dollars on a bunch of work but still end up having the same problem.

What can I do further to ensure that I've identified the problem and that an insert/liner will fix it?

Would you recommend the airtight door instead of the insert? Why?

If I go with an insert and liner, what details do I need to pay attention to in order to make sure all the work is done and all the accessories added to ensure a stink-free home?

What other information do you need from me to help resolve this?



I can't tell you how desperate we are to just get this fixed, and I'm ever so grateful for any help to get it fixed the RIGHT WAY. Thanks!

Oh, and I tried uploading a "media album" with descriptions of my pics, but it said that a moderator had to approve it before I could add it to this thread. So, I've attached the pics directly for now.

EDIT: I forgot to make this point: in the first thread, the last few comments are from people saying they think I'm dealing with an issue of negative pressure and moisture in the flu.

I think there's no denying this, based on the symptoms. I didn't make this thread because I discount/disbelieve/don't value their input. I made this thread because I'm hoping that, with the pics and additional info I've given, we might be able to more accurately identify the causes of these issues and ensure that whatever work I have done will actually make a difference.

So, I guess what I mean is, I'm hoping here to fine tune and build upon the great advice already given. I'm not trying to throw away what others already said and start over.
 

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Stu, I stand by my negative pressure comments on the other thread, but I will watch this one with an open mind. I would love to see some manometer readings showing pressure differentials for your house.

One question based on the new pictures. Is the dryer vent looking thing half way up the outside of the chimney for makeup air? This question is for you, Stu, and those who know more about these "heatilator" fireplaces. I know squat.
 
Has the fireplace ben cleaned since those pictures where taken? I see lots of glaze in the flue which with the slightest bit of moisture will smell horrible.
 
It's very common for fireplaces to stink in the summer months. There is nothing "wrong" with your fireplace. A good cleaning, block off plate, insert and a liner will be your best bet.
I have a locktop damper and still get the smell on hot humid days. I plan to get an air seal door in the near future.
 
We have an insert that is currently disconnected from the flue for a few repairs. The flue and firebox around the insert was just cleaned with very little creosote, but we still have a little dank fireplace smell in our house. Very humid here right now.

I am not expert, but I would say keeping it clean and sealing up the insert and/or the firebox would be your first steps. And as Boiler74 said, there very well could be certain weather conditions causing a negative pressure inside the home sucking smelly air in.

The cooler damp air we had here the last few days has really made the area around the fireplace smelly since it is wide open right now. Never have this problem when it is all sealed up.
 
I think in many cases it has a lot to do with the cold air returns. Thier location as well as the balance of the system. The return air has to be taken from somewhere, the fireplace is a perfect source.
 
Stu, I stand by my negative pressure comments on the other thread, but I will watch this one with an open mind. I would love to see some manometer readings showing pressure differentials for your house.

One question based on the new pictures. Is the dryer vent looking thing half way up the outside of the chimney for makeup air? This question is for you, Stu, and those who know more about these "heatilator" fireplaces. I know squat.

I meant to point out in my OP on this thread that I completely agree we're dealing with negative pressure and moisture. What I'm hoping to do here is to see if folks can help me pinpoint causes, or at least ensure that whatever I pay to have done will actually make things better.

For example, with the negative pressure issue, a lot of people in the last thread (rightfully) honed in on the exhaust fan. However, I turned off the fans for over a month and it had literally no impact on the smell. Now, it could be that we'll never no for 100% certain what is causing the negative pressure, but if I can get advice on ensuring that the insert is installed in such a way that there's as little chance possible of the flue/insert being the place that feeds this negative pressure, and the house has to suck from somewhere else that doesn't smell as bad, then it won't matter.

Likewise with the moisture. I agree there's likely moisture getting in. I don't see the standing water and trickles that one sweep claimed to see (and that the others completely disagreed with). Plus, I've had the top of the flue open for months now, with very little improvement (if I remove the balloon, it smells as bad as on day one), so I don't know if me having the flue plugged on both ends can still be pointed to as the cause. If I had help on identifying the cause of this, or at least advice on how to ensure that this is fixed, that would be awesome.

With regards to your question about the vent, that goes straight into the bottom of the fireplace. The sweeps here called it either a "cold air vent" or a "combustible air intake." They all said that it's rare, but very good to have. I keep it plugged up with insulation and aluminum foil on the inside, which I remove when it's time to burn. It has no ash or creosote in it, so everyone has agreed it's not the source of the smell.
 
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Has the fireplace ben cleaned since those pictures where taken? I see lots of glaze in the flue which with the slightest bit of moisture will smell horrible.

It hasn't been cleaned since the pics were taken. I realize now that we did burn once or twice after the cleaning, which is why you can see some fine ash on everything.

All the sweeps that came out told me that there will always be some amount of glaze, especially on a 30 year old flue. They said my flue is as clean it can get. Were they wrong?
 
It's very common for fireplaces to stink in the summer months. There is nothing "wrong" with your fireplace. A good cleaning, block off plate, insert and a liner will be your best bet.
I have a locktop damper and still get the smell on hot humid days. I plan to get an air seal door in the near future.

If an insert and liner is the best bet, why are you sticking with a fireplace instead of an insert? I ask only because I considered going that route (fireplace with air seal door) instead of an insert.

Also, when I look at the diagrams of how an insert works, it seems like that block off plate is the only thing that would keep air from the flue out of the house (besides the surround plate on the outside of the insert). Is that correct? Is there anything else I can do to ensure no stinky air from the clay tiles that have 30 years of burnt on gunk comes into the house?

Also, with regards to nothing being wrong, on really hot humid days, the smell makes it all the way back to my master bedroom, which is pretty far away. I've never experienced this type of odor intrusion while growing up in a woodburning house. I get that it will often smell right next to the fireplace, and on bad days even within the same room as the fireplace, but when the entire main level of the house stinks, that seems excessive.
 
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If an insert and liner is the best bet, why are you sticking with a fireplace instead of an insert? I ask only because I considered going that route (fireplace with air seal door) instead of an insert.

Also, when I look at the diagrams of how an insert works, it seems like that block off plate is the only thing that would keep air from the flue out of the house (besides the surround plate on the outside of the insert). Is that correct? Is there anything else I can do to ensure no stinky air from the clay tiles that have 30 years of burnt on gunk comes into the house?

Also, with regards to nothing being wrong, on really hot humid days, the smell makes it all the way back to my master bedroom, which is pretty far away. I've never experienced this type of odor intrusion while growing up in a woodburning house. I get that it will often smell right next to the fireplace, and on bad days even within the same room as the fireplace, but when the entire main level of the house stinks, that seems excessive.
Because I have to stoves that I heat with. The fireplace is just for fun and it's lined with soapstone, so I'd hate to hide it with an insert.
 
It hasn't been cleaned since the pics were taken. I realize now that we did burn once or twice after the cleaning, which is why you can see some fine ash on everything.

All the sweeps that came out told me that there will always be some amount of glaze, especially on a 30 year old flue. They said my flue is as clean it can get. Were they wrong?
That flue isn't even close to being clean. There are a few processes that will remove that glazed creosote. I rarely ever see glaze like that in an open fireplace. With unlimited air it's not real common, under seasoned wood is really the only way for this to happen.
 
That flue isn't even close to being clean. There are a few processes that will remove that glazed creosote. I rarely ever see glaze like that in an open fireplace. With unlimited air it's not real common, under seasoned wood is really the only way for this to happen.
We see it quite often many times on fireplaces with doors where the air flow is restricted or bad fireplace design. And yes wet wood is usually a factor also. But yes we would get it much cleaner than that for sure. We may not get it spotless unless the customer is willing to pay for chemical cleaning but a set of rotary chains will take most of that off.
 
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So it seems it's pretty well established by now that the glaze creosote is causing the stink when it gets damp and reverse draft gets it into the house. Even without the bad creosote build-up you have, some stink may continue to be a problem unless the draft problem is solved too. In any case, that glaze has to be removed, not only for the stink, but for the fire hazard as well.

If it were me, I would look seriously at the chemical treatment bholler mentioned (TSR?) Probably expensive, but thorough. Then with the chimney really clean and the damper on top to minimize the downdraft, and a tight door, I would think the problem would be largely solved. But I would defer to the pros here.

I don't know why none of your consultants mentioned the glaze and options for removal, but it seems to me that you still need to find a sweep that is willing to do what it takes and is capable. That stage three stuff is quite hazardous. I'd advise no more burning until the creosote is removed one way or another.

Here is a quote from a FAQ on another site that shows it is not an unusual problem:
My fireplace stinks, especially in the summer. What can I do?

The smell is due to creosote deposits in the chimney, a natural byproduct of wood burning. The odor is usually worse in the summer when the humidity is high and the air conditioner is turned on. A good cleaning will help but usually won't solve the problem completely. There are commercial chimney deodorants that work pretty well, and many people have good results with baking soda or even kitty litter set in the fireplace. The real problem is the air being drawn down the chimney, a symptom of overall pressure problems in the house. Some make-up air should be introduced somewhere else in the house. A tight sealing, top mounted damper will also reduce this air flow coming down the chimney
.
From this site: http://strictlychimneys.com/frequently-asked-questions.cfm

Then, dry wood, dry wood, dry wood.
 
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I meant to point out in my OP on this thread that I completely agree we're dealing with negative pressure and moisture. What I'm hoping to do here is to see if folks can help me pinpoint causes, or at least ensure that whatever I pay to have done will actually make things better.

For example, with the negative pressure issue, a lot of people in the last thread (rightfully) honed in on the exhaust fan. However, I turned off the fans for over a month and it had literally no impact on the smell. Now, it could be that we'll never no for 100% certain what is causing the negative pressure, but if I can get advice on ensuring that the insert is installed in such a way that there's as little chance possible of the flue/insert being the place that feeds this negative pressure, and the house has to suck from somewhere else that doesn't smell as bad, then it won't matter.

Likewise with the moisture. I agree there's likely moisture getting in. I don't see the standing water and trickles that one sweep claimed to see (and that the others completely disagreed with). Plus, I've had the top of the flue open for months now, with very little improvement (if I remove the balloon, it smells as bad as on day one), so I don't know if me having the flue plugged on both ends can still be pointed to as the cause. If I had help on identifying the cause of this, or at least advice on how to ensure that this is fixed, that would be awesome.

With regards to your question about the vent, that goes straight into the bottom of the fireplace. The sweeps here called it either a "cold air vent" or a "combustible air intake." They all said that it's rare, but very good to have. I keep it plugged up with insulation and aluminum foil on the inside, which I remove when it's time to burn. It has no ash or creosote in it, so everyone has agreed it's not the source of the smell.

Why don't you describe the rest if the house. Do you have vaulted ceilings? Lots of recessed /can lights? Air supply and return ducts in the attic? Are you vents in the ceilings? Return air too? Any other "holes" in the ceiling?
 
That flue isn't even close to being clean. There are a few processes that will remove that glazed creosote. I rarely ever see glaze like that in an open fireplace. With unlimited air it's not real common, under seasoned wood is really the only way for this to happen.

This is what it looked like when I got here (which reminds me of something I failed to emphasize: we never had even a tiny bit of smell during our first summer here, before we had burned), so I don't think it's from the wood we burned. I'm surprised that none of the four or five sweeps we've had out here had any concerns about it. They all said it was about as clean as it could get. :(

What can I do to fix this?
 
We see it quite often many times on fireplaces with doors where the air flow is restricted or bad fireplace design. And yes wet wood is usually a factor also. But yes we would get it much cleaner than that for sure. We may not get it spotless unless the customer is willing to pay for chemical cleaning but a set of rotary chains will take most of that off.

I don't understand why literally four or five sweeps told me that my chimney and fireplace were just as clean as they should be!? One mentioned that there was a bit of glaze in the flue, and that chains could get glaze off, but he said that there's always some amount of glaze, and that the amount of glaze we have is "nowhere near enough to justify using chains yet."

This is what the fireplace and flue looked like when we got here, so I don't think our one season of burning did it. On the other hand, we didn't have any smell AT ALL during our first summer here (before we started burning), so maybe it is from us?

I don't even know what to think. There's only one sweep in my town, and I had to pay all the others to come from another town over 50 miles away. These are literally the only sweeps available to me. If none of them were able to spot that my flue and fireplace are in bad shape, how am I supposed to get the help I need (let alone trust them to install an insert correctly)?

I'm honestly at a bit of a loss now.
 
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I don't understand why literally four or five sweeps told me that my chimney and fireplace were just as clean as they should be!?
I dont understand it either. We would always clean with chains if a flue looked like that. That stuff is very flammable. I don't know what to tell you either if all of the sweeps you have access to are that incompetent. Maybe become a sweep there is obviously a need for a good one in your area. lol
 
Why don't you describe the rest if the house. Do you have vaulted ceilings? Lots of recessed /can lights? Air supply and return ducts in the attic? Are you vents in the ceilings? Return air too? Any other "holes" in the ceiling?


No vaulted ceilings.

The kitchen has several recessed lights, and two other rooms on the main level each have one can light in them. During the recent weatherization work, every single can light was enclosed from the other side, so they're supposed to be sealed.

The only ducts I know of in the attic are the ducts going from the bathroom fans over and out through the eaves. There are channels that allow air to exchange through the grates in the eaves, but I'm not sure if those are "ducts".

Air vents are all in the floor on the main level, with returns in the wall. In the basement, the vents are in the ceiling, with returns still in the walls.

The only other hole in the ceiling I can think of is there is a large (2'x2'?) vent for an old attic fan in the hallway ceiling. However, that has a box built over it out of insulation, plus we sealed it on the inside with plastic weatherization film and two-sided tape.

Based on the other comments about my chimney being filthy, I'm starting to get pretty stressed out. Literally every sweep within 75 miles has told me that my flue and fireplace are as clean as they can reasonably get. If every single "expert" I can access is so wrong, what the heck am I supposed to do?
 
I dont understand it either. We would always clean with chains if a flue looked like that. That stuff is very flammable. I don't know what to tell you either if all of the sweeps you have access to are that incompetent. Maybe become a sweep there is obviously a need for a good one in your area. lol

They're all licensed and certified. Eff! Which picture are you referring to specifically? The one looking down into the flue? That's fairly low resolution. Is it just the fact that it is black that's a bad sign?

They all told me that there is always some level of glaze that's impossible to get out, especially on a 30 year old flue, but that mine had none of the "dangerous" glaze (I think they called it "stage 3"?). When I asked about chains, I was specifically told it wasn't called for yet!

Will chains be enough? Someone else mentioned chemicals? Can they even clean the inside of the fireplace with chains?

Is there any of this I can do on my own? I know you were joking about becoming a sweep, but if any of this is reasonably DIY, I would actually feel better, since I obviously wasted a ton of money on these "experts."

Sorry for all the questions. I feel like I'm probably the most annoying person in the world, but everyone here has been so kind and patient. It means a lot to us.
 
So it seems it's pretty well established by now that the glaze creosote is causing the stink when it gets damp and reverse draft gets it into the house. Even without the bad creosote build-up you have, some stink may continue to be a problem unless the draft problem is solved too. In any case, that glaze has to be removed, not only for the stink, but for the fire hazard as well.

If it were me, I would look seriously at the chemical treatment bholler mentioned (TSR?) Probably expensive, but thorough. Then with the chimney really clean and the damper on top to minimize the downdraft, and a tight door, I would think the problem would be largely solved. But I would defer to the pros here.

I don't know why none of your consultants mentioned the glaze and options for removal, but it seems to me that you still need to find a sweep that is willing to do what it takes and is capable. That stage three stuff is quite hazardous. I'd advise no more burning until the creosote is removed one way or another.

Here is a quote from a FAQ on another site that shows it is not an unusual problem:

From this site: http://strictlychimneys.com/frequently-asked-questions.cfm

Then, dry wood, dry wood, dry wood.

Ugh. They literally, specifically, explicitly told me I don't have stage 3!

How can I verify for myself what stage I have? I was initially worried because of how black everything is, but they all told me that's to be expected with a 30 year old chimney. They said that black, and even a bit of shine, isn't a problem, and it's only worrisome when there's crusty, crackly stuff.

Is the flue literally supposed to be terra cotta color, like a brand new one, with no black on it at all?
 
Which picture are you referring to specifically?
the one looking down the flue showing the shiny black glaze.

They all told me that there is always some level of glaze that's impossible to get out, especially on a 30 year old flue
That is completely false.

Will chains be enough? Someone else mentioned chemicals? Can they even clean the inside of the fireplace with chains?
I dont know without seeing it and trying chains.

Is there any of this I can do on my own? I know you were joking about becoming a sweep, but if any of this is reasonably DIY, I would actually feel better,
It would be possible but it would take a fair investment to get the required equipment and then the chains may not even work. As far as the chemicals go I dont know if any of the good ones are available to non pros

Sorry for all the questions. I feel like I'm probably the most annoying person in the world, but everyone here has been so kind and patient. It means a lot to us.
no problem at all I come here to help people and you are not being annoying at all you atleast listen to the advice given. The only people who bother me are the ones that ask questions and then disregard the answers given by those who know more about it than them.

Is the flue literally supposed to be terra cotta color, like a brand new one, with no black on it at all?
not like new no but you should see some orange and there should be no shiny black buildup.
 
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Which picture are you referring to specifically? The one looking down into the flue? That's fairly low resolution. Is it just the fact that it is black that's a bad sign?
Black, shiny, hard and built up. I wonder if you could get better pics of the glaze from the top and from the bottom? It seems so bizarre that four or five certified sweeps would not recognize it as stage 3 glaze and offer solutions for pay, I'm wondering if we're missing something. Does it look like the pic all the way through the flu?

Can you chip a little chunk off at the top and describe it?
 
1) You are unlikely to ever clean a chimney enough to remove the smell. Ask a smoke / fire restoration place, but they typically put items in an ozone chamber (which is a strong chemical oxidant) for days so the ozone can oxidize every last molecule of 'smoke'. Even a thorough surface cleaning will not be enough and the smell will leach right back out of the masonry ready for another stink bomb when the atmosphere is right. Perhaps if you could soak the flue in chlorox (another strong chemical oxidant) or seal it and ozone it for days to weeks...but anything short of that ...even an extremely thorough mechanical cleaning will leave the smell behind. Give up while you're ahead and still relatively sane.

2)What causes smell. Anytime you house air is warmer and less dense than the outside air, (fall, winter, early spring) it wants to rise up and out...so things work normally... That house air would like to rise up and out the flue, or up and out cracks at the ceiling, light fixtures, etc. ...minimal, if any smell.

Any time the house air is cooler and more dense than outside, (late spring, warm/rainy days (remember - humid air is less dense than dry air), summer, early fall) things want to flow in reverse Anytime you open a door, that cool dense air wants to spill out of your house ...any cracks at floor level, baseboards, etc ...air wants to spill out. When that cool air spills out, air needs to come in to replace it...down the flue is always an easy option! Summer can also bring a compounding factor of a super hot attic trying to release air out ridge vents. If you do not have plenty of soffit vents to balance that flow (or they have been covered up over the years), it can create a negative pressure in the attic and pull house air through recessed ceiling lights, attic fan openings, ceiling cracks, etc. That house air needs to be balanced so once again, air down the flue is an easy make-up source.

Strong winds can also create a 'vacuum' effect - pulling air from your attic and/or house which needs to be made up by air coming in...down the flue.

Surprisingly, all your weatherization efforts may make things worse. Air is coming down the flue because some other effect is pulling it out of the house. If what ever is pulling it out brought some down the flue, some through a door, some through a window, etc - you may only have a little smell. Seal up those doors and windows, then ALL the replacement air has to come through the flue and bring smell with it.

I tried taping aluminum foil across the entire fireplace door. That helped with the smell, but it made so much noise from getting sucked in and out by the air coming in/out through the drafty damper, that we couldn't stand it.

OK - now we're getting somewhere! If there is so much air movement up/down the flue that a covering rattles to unacceptable levels? The two key things I would look at to stop the smell:

1) Get an air-tight flue covering / cap. This means 'really' air tight...not a bag stuffed with newspaper, or a piece of plastic tied with string, but an honest piece of steel, solid wood, or rigid plastic with a thick foam gasket which completely seals to the masonry and can withstand a bit of positive / negative pressure with no air leakage. Any air leakage = smell, but no air in means 'virtually' no air out. A tight seal up top plus closing your leaky damper would likely eliminate 90+% of the smell...you're effectively locking that air in the chimney.

If the remainder of the smell is still unacceptable, then I'd look at sealing the bottom end. With a solid / tight seal up top, you should not have any rattling and with a positive seal at the bottom, ALL the smell is simply trapped.

Good luck!
 
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