Nightmare woodstove smoke! I am stumped... 21 feet of flue, can't get a draft.

Longtime lurker,  If there is any place I can think of that might help me crack this code It is this forum!  I've read countless posts/videos for getting drafts/smoke and I just find find a smoking gun (ha...)  that fits my situation.

I'm a long time wood burner,  This is my 3rd self built home with a wood stove.  My last two homes used Englander NC30's.  I loved that stove.   Not the best, but a wonderful price vs performance.    My newest place, I bought a used but good condition Us stove/country hearth model 2000,   (a welded EPA stove circa 2016/2017)    The home is pretty tight and well insulated, and smaller so I did not want one of those large stoves again.

This is second stove I've had installed, here  I had been given a Garrison II, double door (pretty small!) that I used all last winter.  It was not efficient but I learned its ropes but I still had a smoke leaking problem.    The garrison was a leaky stove.  This US stove appears to be virtually air-tight.

My last two homes, Had only the most occasional trouble with back drafts, almost always caused by impatience, I also skirted the bare min on the length of the chimney.  I probably had 13' feet of flue ontop of the stove Max,  The stoves worked great.

This time,  I am on the side of a hill,  about half way up,  Elevation is 1000' even.    Avg grade is around 5-7 degrees across the property.    There is almost never 'still' air here.  Its usually flowing up or down hill gently.

Stove has 66" of black pipe to the ceiling box,  Then it has 5x  3' triple wall sections going through the upstairs future bath, and up out side.  There is a 7' stem out of the roof roughly.    Yes I know,  I had to put a bend in the pipe, because I had to move the stove over 16" when,  my staircase had to become a winder.  (I didn't  think that far ahead!)  I know bends are never good in pipe, but I've done it before with only a small reduction in draft,  And I assumed with 15' of stainless pipe above it it would draw like a beast.    I have not sealed the joints, I have never sealed the joints in the past, and I am unsure if any amount of sealing is going to solve this.

No  matter what I do, if I do so much as crack the door the stove half a inch.  Every possible gap in the entire flue blasts smoke out, as if its under pressure.  It is even leaking out of the triple wall sections on the second floor.   This has never happened to me before.  This is with front door located only a few feet from the stove wide open.  

Somehow, the stove is uptaking/air much faster then the flue is sucking it up.

The stainless pipe is clean and clear.  I inspected it twice.  Only a tiny amount of crusty/flakes.  I would call it 98% open.  I looked from the top straight down into the house and vice versa just 5 weeks ago.   Even with a strong fire and mostly/fully damped I will still get a few puffs here and there but it mostly settles down,  however by AM when the stove heat really wanes, I expect it to leak again.

The flue is open and clear.   There is a total of 15' of triple wall stainless.  Why can't this thing pull a draft?  No matter how hot the fire is?   The twin wall in the second floor is warm to the touch.    Last winter there was a brief period, end of dec/most of jan,  Where somehow it seemed the smoking really slowed down.  Not gone but less,  but these more shoulder months its just a nightmare.

I will attach pictures.     What is going on here?!  And what can I do.

You can see it looks windy in the outside picture,  Its always like this,  not terribly windy, but a gentle flow,  that often changes directions.  Is this it???

Couple of thoughts;
- do you have a dedicated air supply pipe for the stove, near the stove?
I ask because air tight homes may not have enough draft cracks for the stove to work prioperly.
- Those bends look weird!!
- maybe a swing top to prevent wind being driven down the flue.
 They also can create a bit of draft as well.
- is the top of the flue higher than the peak of the house?
Sometimes wind eddies are created and strange things happen.

Not a professional here, Is that fire newly lit? I've never had a stove smoke like that unless it was just lit and still burning paper. You can't even see smoke from our chimney when it's going, just a heat haze. That looks like wet wood or not enough air.
Joints should always be sealed or they will suck air in and reduce the draft you get.

We get a lot of wind and a cap on the chimney helps immensely, More than stopping down draft it stops the stove drawing more air that it should in high winds and being impossible to shut down.

You say the house is pretty tight, where is the air for the stove coming from? here there must be unhindered access to outside air for any stove. that can be directly into the stove or through a wall vent close by. If the hot air cannot be replaced by cold air then it won't draw, same as you cannot suck from a closed straw.

Skandi Rogers wrote:Not a professional here, Is that fire newly lit? I've never had a stove smoke like that unless it was just lit and still burning paper. You can't even see smoke from our chimney when it's going, just a heat haze.
Joints should always be sealed or they will suck air in and reduce the draft you get.

We get a lot of wind and a cap on the chimney helps immensely, More than stopping down draft it stops the stove drawing more air that it should in high winds and being impossible to shut down.

You say the house is pretty tight, where is the air for the stove coming from? here there must be unhindered access to outside air for any stove. that can be directly into the stove or through a wall vent close by. If the hot air cannot be replaced by cold air then it won't draw, same as you cannot suck from a closed straw.

Skandi!  Thank you

That fire is was 1 hour old!  As hot as I could/keep it without it smoking too bad.  Even when it full blaze, if I crack the door more than a fraction it leaks terribly,   if I try to load a log with any amount of time to 'build' a draft, it just never comes.  This stove does have a cold air intake, but right now I have the door cracked nearby.

John C Daley wrote:Couple of thoughts;
- do you have a dedicated air supply pipe for the stove, near the stove?
I ask because air tight homes may not have enough draft cracks for the stove to work prioperly.
- Those bends look weird!!
- maybe a swing top to prevent wind being driven down the flue.
 They also can create a bit of draft as well.
- is the top of the flue higher than the peak of the house?
Sometimes wind eddies are created and strange things happen.

John I appreciate it!

If I like this stove I put in a cold air intake, right now I have the door cracked open.
The bend isn't even a full 90,  its a wide angle shot so it looks distorted.   Every joint is tight, (but unsealed)
Top of outside Flue is 'not' above the ridge, but it is more than 10' from the side of the roof.

I just wanted to be sure from the photos.....is the stove installed in a basement or on a main floor?  Thought I recalled something about negative pressure in a basement but can't recall the gist of that notion with respect to woodstove locations.  Also, in case the past thread has some relevant information:

https://permies.com/t/32344/Lets-Talk-WOOD-STOVES-Exhaust

Finally, we surely had wind problems  that were reduced, but not eliminated, by the style of chimney cap shown below.  Hope something here may be helpful!

door cracked open

What does it burn like if the door is wide open? If it gets rip roaring with the door wide open, I second what John says to put in a fresh air vent near the stove.

Abe Coley wrote:

door cracked open

What does it burn like if the door is wide open? If it gets rip roaring with the door wide open, I second what John says to put in a fresh air vent near the stove.

It doesn't matter where the door is really.   So I just spent over half an hour trying to feather the intake air on the stove to increase beyond what the stove full closed up, but damper wide open could pull.  To see if I could warm up the flue more,  It looks like it worked,  I was able to open the door on the stove slowly, for about minute, enough to get a few more logs in and close it without, 'much' leakage.

Could this be some weird,  humidity/dew point differential thing,  combined with constant wind bombardment?

Sorry I thought you were talking about the house door, not the door of the stove. If the house is super tight it just might not be able to pull a draft very well, but  if the front door of the house is open it might rage, etc.

Abe Coley wrote:Sorry I thought you were talking about the house door, not the door of the stove. If the house is super tight it just might not be able to pull a draft very well, but  if the front door of the house is open it might rage, etc.

It seems the house door, has very little effect.   The first two hours of the fire, while I was trying to baby it/keep the smoke out the door was open.

It seems, from your pictures, that the flue is getting much larger towards the ceiling?

I wonder if that has anything to do with it?

I’m not a wood stove specialist either, just thinking of the stuff my former boss told me at the woodstove shop I worked at as an accountant that, if I had a smaller opening coming out of the stove, I wouldn’t want to put a larger pipe going up.

I hope you get your problem solved soon.

Liv Smith wrote:It seems, from your pictures, that the flue is getting much larger towards the ceiling?

I wonder if that has anything to do with it?

I’m not a wood stove specialist either, just thinking of the stuff my former boss told me at the woodstove shop I worked at as an accountant that, if I had a smaller opening coming out of the stove, I wouldn’t want to put a larger pipe going up.

I hope you get your problem solved soon.

Its the same size, it just looks distorted because I used a really wide angle shot from up high!  I'm sorry for the bizarre perspective!

John Weiland wrote:I just wanted to be sure from the photos.....is the stove installed in a basement or on a main floor?  Thought I recalled something about negative pressure in a basement but can't recall the gist of that notion with respect to woodstove locations.  Also, in case the past thread has some relevant information:

https://permies.com/t/32344/Lets-Talk-WOOD-STOVES-Exhaust

Finally, we surely had wind problems  that were reduced, but not eliminated, by the style of chimney cap shown below.  Hope something here may be helpful!

I'm looking at wind diversion caps now.   In the past just a little more air/heat was always able to overcome even the craziest winds at my other houses.   Something is just cursed about this setup!    Its kind of a basement, its basically walkout (passive solar south windows) in the foundation, then a single floor above.   The floor above has the stainless running through a future upstairs bathroom.   Which I thought would help as more of the stainless is in heated space.

joe fish wrote:
I'm looking at wind diversion caps now.   In the past just a little more air/heat was always able to overcome even the craziest winds at my other houses.   Something is just cursed about this setup!    Its kind of a basement, its basically walkout (passive solar south windows) in the foundation, then a single floor above.   The floor above has the stainless running through a future upstairs bathroom.   Which I thought would help as more of the stainless is in heated space.

Maybe nothing, but wanted to add two more things.  I noticed the wind direction in your photo blowing the smoke *towards* the peak of the roof.  This is the same direction that can give us trouble if the wind cranks up near 30 mph or more during good blizzards.  Between the better chimney cap and more wind-break trees recently buffering that wind, the back-smoking problem has been reduced considerably.  When the wind blows from the opposite side of the house, the opposite effect is experienced:  SUCTION across the top of the chimney that practically wants to pull the logs up the stack! (kidding....but you get the idea.)  Secondly, and I'm just guessing here, but is there some aspect to 'temperature differential' between the inside of the chimney and outside of the chimney affecting the upward draw on the air column?  I seem to recall from experience that my RMH project, installed in an outbuilding so that I can play with different stove/stack parameters, runs better when the outside air is REALLY COLD (-25 to -30C).  The woodstove in our home has black exhaust pipe for ~4 ft, then elbows out the wall adapter and immediately connects to exterior class A chimney for a good 20+ feet going up through the roof soffit.  Maybe not so different from yours in overall height, but more stack outside.....where the temperature differential between inner and outer stack is greater??  Really just guessing here....hope others can chime in.

John Weiland wrote:

joe fish wrote:
I'm looking at wind diversion caps now.   In the past just a little more air/heat was always able to overcome even the craziest winds at my other houses.   Something is just cursed about this setup!    Its kind of a basement, its basically walkout (passive solar south windows) in the foundation, then a single floor above.   The floor above has the stainless running through a future upstairs bathroom.   Which I thought would help as more of the stainless is in heated space.

Maybe nothing, but wanted to add two more things.  I noticed the wind direction in your photo blowing the smoke *towards* the peak of the roof.  This is the same direction that can give us trouble if the wind cranks up near 30 mph or more during good blizzards.  Between the better chimney cap and more wind-break trees recently buffering that wind, the back-smoking problem has been reduced considerably.  When the wind blows from the opposite side of the house, the opposite effect is experienced:  SUCTION across the top of the chimney that practically wants to pull the logs up the stack! (kidding....but you get the idea.)  Secondly, and I'm just guessing here, but is there some aspect to 'temperature differential' between the inside of the chimney and outside of the chimney affecting the upward draw on the air column?  I seem to recall from experience that my RMH project, installed in an outbuilding so that I can play with different stove/stack parameters, runs better when the outside air is REALLY COLD (-25 to -30C).  The woodstove in our home has black exhaust pipe for ~4 ft, then elbows out the wall adapter and immediately connects to exterior class A chimney for a good 20+ feet going up through the roof soffit.  Maybe not so different from yours in overall height, but more stack outside.....where the temperature differential between inner and outer stack is greater??  Really just guessing here....hope others can chime in.

I love all these thoughts!

I wouldn't have posted if it was something obvious,  Or at least obvious to me.   In my mind this is simple physics right?  The stove is a wood burning appliance, it requires a draft to work.   The vertical stem of contained hot exhaust gasses, creates a stronger updraft, depending on temp of the exhaust and the height of the stack.   It seems simple,  So clearly I am failing to develop a good updraft for some reason.

maybe tomorrow haul it out and set it up in the driveway with the tallest chimney you can put together and put some super dry wood in it and see if you can get it glowing red hot... then at least you'll know it's not the stove

I noticed there was spray on foam insulation in what looks to be the upstairs or attic area of the house.  This leads me to believe the house is at least fairly well insulated.  Out of all the things already discussed that I didn't hear mention of was the possibility of adding insulation to your stove pipe.  If the flue is losing it's heat too quickly, the flue gasses will struggle to rise and quite possibly want to fall down the pipe when you open the stove door.  Other than that, you might want to research "Stack Effect".  Perhaps you've got something going on there.  Good luck to you.

Frustrating! To me, it seems pretty clear you have a significant downdraft from the local topography. Been there; it was tall trees in my case. My solution was to add another 3' of chimney above the roof. The downside was the need to add chimney supports.

It's probably not the stove, although I have seen ash buildup above the top baffle make a noticeable difference in draft. That doesn't seem like the issue to me.

Good luck!

Thomas Tipton wrote:I noticed there was spray on foam insulation in what looks to be the upstairs or attic area of the house.  This leads me to believe the house is at least fairly well insulated.  Out of all the things already discussed that I didn't hear mention of was the possibility of adding insulation to your stove pipe.  If the flue is losing it's heat too quickly, the flue gasses will struggle to rise and quite possibly want to fall down the pipe when you open the stove door.  Other than that, you might want to research "Stack Effect".  Perhaps you've got something going on there.  Good luck to you.

The triple wall should be well enough insulated?  I don't think i can have anything touch it, I think its suposed to have a 2-4" gap from all surfaces.?  I don't think its loosing heat to quickly... I just seem to be unable to get a real draft going despite having 15' of vertical insulated stack.  I think maybe you are right,   stack effect combined with a challenging site could be it....?   But what is another 3' of stainless pipe going to get?? ugh!

Douglas Alpenstock wrote:Frustrating! To me, it seems pretty clear you have a significant downdraft from the local topography. Been there; it was tall trees in my case. My solution was to add another 3' of chimney above the roof. The downside was the need to add chimney supports.

It's probably not the stove, although I have seen ash buildup above the top baffle make a noticeable difference in draft. That doesn't seem like the issue to me.

Good luck!

Yes the trees are pretty close by, I will update with a day light picture in the am.   I already have 15' of stack,  do you think another 3' is going to give me anything really meaningful?

Abe Coley wrote:maybe tomorrow haul it out and set it up in the driveway with the tallest chimney you can put together and put some super dry wood in it and see if you can get it glowing red hot... then at least you'll know it's not the stove

So I did fire the stove with only KD wood scraps,  I got it cranking just to burn off any 'funk' before installation,  I put 48" of black pipe stack on it, and it cranked!

What is the indoor and outdoor temperature? We sometimes have issues when the temperatures are very similar, or if outside is warmer than inside. You can get a reverse draft effect, especially when getting it started.

I'm also concerned by the quantity of smoke produced. That suggests to me that the internal baffles in the stove are not directing the air to the burn zone correctly. One of our stoves has baffles that are just metal plates resting on tabs. After the chimney was swept one time we had a whole load of issues getting the stove to burn cleanly and get up to temperature. Turns out the baffles had been reinstalled in the wrong spots so the upper air, that is supposed to wash down the front of the door glass, was diverting directly to the flue. This type of issue may partially explain the draft issue you are seeing. Your if lots of cold air is entering the flu stack without passing through a combustion zone you won't get a good chimney effect. combine that with gusts of wind and you could easily get smoke escaping cracks in the flue system.

joe fish wrote:Yes the trees are pretty close by, I will update with a day light picture in the am.   I already have 15' of stack,  do you think another 3' is going to give me anything really meaningful?

If there is a downdraft, the amount of stack above the roof is key. Can you rig some of your black stove pipe on top of the insulated stack and test it?

Howdy,

And is there a spark screen on/in the top cap? Might try without it. I've seen spark screens slow the draft down. To my knowledge, the top of a chimney has to be higher than the peak of the roof. and I'm also not a stovepipe expert.

One more consideration.......Is this a catalytic stove you are using.  I just happened upon a video last night that compared the differences between a secondary air stove and a catalytic stove.  The catalytic stove does not allow as much air to pass through the stove because it all has to pass through the catalytic elements first.  In a sketchy situation, that may simply be too much restriction for a stove to draft properly.  

Have you tried opening a window in the basement? As someone already mentioned, you may not have enough volume of air entering into the house when it's sealed up to offset the volume of exhaust gasses escaping through the chimney.

randal cranor wrote:Howdy,

And is there a spark screen on/in the top cap? Might try without it. I've seen spark screens slow the draft down. To my knowledge, the top of a chimney has to be higher than the peak of the roof. and I'm also not a stovepipe expert.

There is a spark screen,  The top of the flue is not above the roof line, but it is more than 10' away from the roof.  I could take off the arrestor but it seems like its adding very little resistance.

Thomas Tipton wrote:One more consideration.......Is this a catalytic stove you are using.  I just happened upon a video last night that compared the differences between a secondary air stove and a catalytic stove.  The catalytic stove does not allow as much air to pass through the stove because it all has to pass through the catalytic elements first.  In a sketchy situation, that may simply be too much restriction for a stove to draft properly.  

It is a non catalytic,  but it does have a secondary burn   It does look like all the baffles re working well and in the correct place.

Nick Kitchener wrote:Have you tried opening a window in the basement? As someone already mentioned, you may not have enough volume of air entering into the house when it's sealed up to offset the volume of exhaust gasses escaping through the chimney.

I let my basement door stay 'leaky'  It is only a few feet away from this stove, its one of the reasons I have not put in a cold air intake yet, As  that requires work but leaving the door cracked a few feet away is the lazy solution  But I do want to install one.   It seems even if I leave the door wide open it makes no different to allow the draft to build.

Michael Cox wrote:What is the indoor and outdoor temperature? We sometimes have issues when the temperatures are very similar, or if outside is warmer than inside. You can get a reverse draft effect, especially when getting it started.

I'm also concerned by the quantity of smoke produced. That suggests to me that the internal baffles in the stove are not directing the air to the burn zone correctly. One of our stoves has baffles that are just metal plates resting on tabs. After the chimney was swept one time we had a whole load of issues getting the stove to burn cleanly and get up to temperature. Turns out the baffles had been reinstalled in the wrong spots so the upper air, that is supposed to wash down the front of the door glass, was diverting directly to the flue. This type of issue may partially explain the draft issue you are seeing. Your if lots of cold air is entering the flu stack without passing through a combustion zone you won't get a good chimney effect. combine that with gusts of wind and you could easily get smoke escaping cracks in the flue system.

Outside temp was 19F,  Inside was 68F.
Basement stove 68f,  5' of black pipe 68f,  7' of stainless triple wall pipe 68f, Then 8' of triple wall outside,  19f.

I assumed more triple wall pipe located inside the 'house' would also contribute to more stack updraft pressure?

The stove appears to be in good working order, the secondary burn baffles are intact!  I know what you mean about the air wash, I believe its working correctly.

After 30 minutes of burn time, is the fire burning well inside the stove?  Or is it smokey in the firebox?  If you gently crack the stove door open does the fire kick up into a blaze?  

I'm wondering if the stove is getting enough air through it's air inlet damper thingie.  If it's choking it down more than you think, it could cause the smokey exhaust.  But then it should rage into a hot fire when you crack open the stove door and let it start to suck in air.  And pour smoke into the room if you open the door more than a crack (before the draw is able to take advantage of the open door).

Very dumb question but are you using dry wood?

I lived in a place with a similar issue. If the wind was from the north, the stove would not draw. If a big fire was kept going, it would only smoke back occasionally. The wind would change or gust and a stream of smoke or flames would blow out the damper. Starting a fire with a north wind was impossible. With a north window open, you would think the positive pressure forcing cold air into the place would have to force the hot gasses up the flue, or at least neutralize whatever is causing the problem, but no. Or open windows on all sides would have to work, but no. I tried everything I could think of on a budget, and maybe helped it a bit but never solved it. I came to the conclusion that the exact shape of the building and it's cracks and crevices, and the exact pattern of the air currents in the area with a north wind must have created a suction that simply could not be overcome in that building.

Mike Haasl wrote:After 30 minutes of burn time, is the fire burning well inside the stove?  Or is it smokey in the firebox?  If you gently crack the stove door open does the fire kick up into a blaze?  

I'm wondering if the stove is getting enough air through it's air inlet damper thingie.  If it's choking it down more than you think, it could cause the smokey exhaust.  But then it should rage into a hot fire when you crack open the stove door and let it start to suck in air.  And pour smoke into the room if you open the door more than a crack (before the draw is able to take advantage of the open door).

Very dumb question but are you using dry wood?

Good questions!

I believe the fire burns well.  I inspected the draft/damper it was clear before Installed the stove.   If I have the damper full closed it tries to secondary burn, If I full open the damper, the fire will burn stronger.  If I crack the door it will start blazing.   However, no matter I do, the stove is pushing the exhaust up harder than the flue draft can suck it out so smoke just 'shoots' out of every crack on the flue.  (it looks the smoke is being pushed under pressure into the house.

The wood is unburned wood from last year.  Its the best wood I've ever had.  I could do a moisture test.  But I consider it DRY.

Jordan Holland wrote:I lived in a place with a similar issue. If the wind was from the north, the stove would not draw. If a big fire was kept going, it would only smoke back occasionally. The wind would change or gust and a stream of smoke or flames would blow out the damper. Starting a fire with a north wind was impossible. With a north window open, you would think the positive pressure forcing cold air into the place would have to force the hot gasses up the flue, or at least neutralize whatever is causing the problem, but no. Or open windows on all sides would have to work, but no. I tried everything I could think of on a budget, and maybe helped it a bit but never solved it. I came to the conclusion that the exact shape of the building and it's cracks and crevices, and the exact pattern of the air currents in the area with a north wind must have created a suction that simply could not be overcome in that building.

Oh dear... You really get it! Thank you!!!

And now I'm terrified! ack!  I am thinking I should get a windy flue cap.  Or one of those spinners that people usually don't like (for frear of overfiring)  I could add another 3' to stack.  But it still would not be above the peak,  just even further from the roof.   If I add another stack will absolutely have to brace the stack.

I'm really stuck here.  a vacu-cat or wind cap, is the easiest mod.  Everything else is going to get expensive, and I just don't know if its going solve it.???

A while back we had a Permie who had a RMH that wouldn't draft properly.  I can't even imagine now  how many posts were written before it was finally discovered that the rodent screen on top of the chimney was full of cottonwood dander and Lord knows what else.  So whatever you do, be absolutely certain that your flue path is clear.  I'm out of ideas!  

Thomas Tipton wrote:A while back we had a Permie who had a RMH that wouldn't draft properly.  I can't even imagine now  how many posts were written before it was finally discovered that the rodent screen on top of the chimney was full of cottonwood dander and Lord knows what else.  So whatever you do, be absolutely certain that your flue path is clear.  I'm out of ideas!  

its completely clear!  I am currently blaming the wind/site/topography!    But I'm triple checking everything,  Cotton wood dander, that is amazing!

I wonder if it's possible to make something like a weathervane, but that shields the top of the chimney according to the direction of the wind? If you know what direction the wind is coming from, it's possible to shape the opening so the wind draws the smoke out, but I'm not aware of any that adjust that opening automatically when the wind changes. Such a thing seems like it would be useful.

Granted, I haven't done a lot of research into existing chimney designs. It's always been on my list, but never near the top.

Ellendra Nauriel wrote:I wonder if it's possible to make something like a weathervane, but that shields the top of the chimney according to the direction of the wind? If you know what direction the wind is coming from, it's possible to shape the opening so the wind draws the smoke out, but I'm not aware of any that adjust that opening automatically when the wind changes. Such a thing seems like it would be useful.

Granted, I haven't done a lot of research into existing chimney designs. It's always been on my list, but never near the top.

I've seen pictures of such but have never seen one for sale or in use here. They had a bearing like a weathervane to always face away from the wind. I don't think they were a very big success, maybe because of the bearings failing?

I've seen the upslope on a roof catch the prevailing wind and increase the draw of a wood stove chimney. I wonder if a piece of flashing or steel roofing could be cut and strapped on to the pipe to create the same effect?

Jordan Holland wrote:

Ellendra Nauriel wrote:I wonder if it's possible to make something like a weathervane, but that shields the top of the chimney according to the direction of the wind?

I've seen pictures of such but have never seen one for sale or in use here. They had a bearing like a weathervane to always face away from the wind. I don't think they were a very big success, maybe because of the bearings failing?

I've seen these installed on commercial greenhouses and I think they work pretty well in those instances.  There is one aspect that may be troublesome, however, in very cold regions and that might be freeze-up of the rotational mechanism.  If the heat exiting the chimney generally is sufficient to melt any ice that might lock the cap in an undesired position, that would be fine, but if it gets locked in the wrong position, it could be a nightmare.  The Vacu-Stack style....of which I think there are several manufacturers,...... is fixed (no moving parts) and may provide enough down-draft relief without the risk of Uber-Updraft promotion.  Will be very curious about the successful outcome if one  is found!