Creosote smell and pipe oozing

[sourceless]

Hello fellow stovers!
Having a stove for the first time and I cannot cope with creosote smell for over an year.
Stove: Dovre TAI55WD (bought second hand)

Short story:
Whenever the stove heats up above 200-220C (390F) it starts giving off a cantran heavy smell(I guess it's creosote), right where
the chimney piping connects to the stove. And creasote leaks from metal chimney piping.

Long Story:
When I first started the stove when heated above 200C it gave the bad smell on the left side where it connects to the top.
It's cast iron parts so I disassembled it whole, cleanined it, degreased, and assembled. Things improved but it was still giving
from the stove exhaust where it connects to the chimney piping. There was a connection flange with cloth/asbestos sealant, which I removed
and put high heat 1500 Celsius (2732 F) resistant silicone sealant. Still continued. Might be from the flange to pipe connection.

At first I had 13cm (5.1 inches) chimney sheet metal pipe with lots of twists and corners. Manual said it needed 15cm (5.9 inches).
I thought that the smaller diameter and lots of turns chocked the woodstove. So I changed the piping with heavy duty, thick metal
pipe 0.08 inches with much less corners. Also I used a stove sealant for 1500C to try to seal up the pipe/stove flange connection. I guess
I did not get a good job degreasing and sealant chipped off after a while.

A new additional problem appeared - black liquid started oozing from the metal chimney piping (second pic above). I read here on the forum that it could be water entering from the top but I guess it's not possible because there are two 90 degree turns until it exits. Metal piping makes a turn before it reaches the chimney body made of chimney circle bricks with diameter 25cm (9.8 inches). Or because it could just melt because of the high temp (might be this).I saw offers of pipe male sides pointing down but I won't be able to do it at the very bottom with the stove top flange. I have the option to move the flange (exhaust) at the back of the stove. and put a 90 degree knee with a service opening. This way I might be able to do all males pointing down.

I followed the rules of the outside chimney in the stove's manual. It's not above the ridge because it's more than 3 meters (10 feet) away from it. Outside chimney has insulation. I'm afraid even now it's too tall without having reinforcement. It might fall. It's exactly 4 meters (13 feet) high from the stove top.

I don't have a ventilation louver where to suck air from. I guess I have enough holes in the house. Could be wrong.

As if some preassure builds in the stove and pushes it out wherever it can and the chimney cannot suck it up.

There is enough temperature differance when I test the stove. Like 5-10C (40-50F) outside. I've tested on windy and non-windy days.

I'm quite desperate at this moment after so much testing and work. It's time consuming to keep the stove under 200C. Even bought a laser thermometer to keep it under. Also a CO meter. Normal working temp by the manual says about 350C (662F). I have to vent the whole house when it reaches higher temps than 200C.

Really hope you could point me in a direction.

Cheers!

p.s. - shall I try higher metal outside chimney with double wall insulated. It could help me remove the two 90 degrees by going just straight up.

 

[bholler]

Hello fellow stovers!
Having a stove for the first time and I cannot cope with creosote smell for over an year.
Stove: Dovre TAI55WD (bought second hand)

Short story:
Whenever the stove heats up above 200-220C (390F) it starts giving off a cantran heavy smell(I guess it's creosote), right where
the chimney piping connects to the stove. And creasote leaks from metal chimney piping.

Long Story:
When I first started the stove when heated above 200C it gave the bad smell on the left side where it connects to the top.
It's cast iron parts so I disassembled it whole, cleanined it, degreased, and assembled. Things improved but it was still giving
from the stove exhaust where it connects to the chimney piping. There was a connection flange with cloth/asbestos sealant, which I removed
and put high heat 1500 Celsius (2732 F) resistant silicone sealant. Still continued. Might be from the flange to pipe connection.

At first I had 13cm (5.1 inches) chimney sheet metal pipe with lots of twists and corners. Manual said it needed 15cm (5.9 inches).
I thought that the smaller diameter and lots of turns chocked the woodstove. So I changed the piping with heavy duty, thick metal
pipe 0.08 inches with much less corners. Also I used a stove sealant for 1500C to try to seal up the pipe/stove flange connection. I guess
I did not get a good job degreasing and sealant chipped off after a while.

A new additional problem appeared - black liquid started oozing from the metal chimney piping (second pic above). I read here on the forum that it could be water entering from the top but I guess it's not possible because there are two 90 degree turns until it exits. Metal piping makes a turn before it reaches the chimney body made of chimney circle bricks with diameter 25cm (9.8 inches). Or because it could just melt because of the high temp (might be this).I saw offers of pipe male sides pointing down but I won't be able to do it at the very bottom with the stove top flange. I have the option to move the flange (exhaust) at the back of the stove. and put a 90 degree knee with a service opening. This way I might be able to do all males pointing down.

I followed the rules of the outside chimney in the stove's manual. It's not above the ridge because it's more than 3 meters (10 feet) away from it. Outside chimney has insulation. I'm afraid even now it's too tall without having reinforcement. It might fall. It's exactly 4 meters (13 feet) high from the stove top.

I don't have a ventilation louver where to suck air from. I guess I have enough holes in the house. Could be wrong.

As if some preassure builds in the stove and pushes it out wherever it can and the chimney cannot suck it up.

There is enough temperature differance when I test the stove. Like 5-10C (40-50F) outside. I've tested on windy and non-windy days.

I'm quite desperate at this moment after so much testing and work. It's time consuming to keep the stove under 200C. Even bought a laser thermometer to keep it under. Also a CO meter. Normal working temp by the manual says about 350C (662F). I have to vent the whole house when it reaches higher temps than 200C.

Really hope you could point me in a direction.

Cheers!

p.s. - shall I try higher metal outside chimney with double wall insulated. It could help me remove the two 90 degrees by going just straight up.

For starters your pipe is upside down that's why you are getting leakage

 

[St. Coemgen]

My first thoughts:

1) That is a long pipe. Is it single walled, double walled or insulated? If single walled, or double walled but not insulated, then if the room is cold then any moisture in the smoke may condense on the cold pipe and leak. If you do a full male toward the stove setup you will not see the leak, but that may simply hide the problem. Pipes should not leak like this in your setup, from things like rain, even if female toward the stove. So this is indeed of concern.

2) A possible contributing issue may be if your wood is dry enough or not. Is your wood, tested on a fresh spit, dry below 20% moisture? If not, then that can exasperate the issues in (1) above. In this case, you need to burn dry wood. (Side note: I see you are living in Bulgaria. Living myself in Hungary, I know it can be difficult to buy dry wood direct .. I have to buy a year or two in advance and dry it myself before I can burn it properly).

3) What is the length of your horizontal pipe after the bend in your photos to when it goes up vertically in the chimney? A too long horizontal pipe can cause issues in air flow, draft and cold pipe issues (see again (1) above).

Hope this helps.

 

[sourceless]

@bholler Will try to get that fixed.

@St. Coemgen
1) It's single wall very thick steel

2) I've tested all kinds of wood. It always smells from the collar/flange when high temp is reached. Despite cleaning stove and pipes thoroughly. Always... Currently using 1.5year seasoned hardwood.

3) Horizontal length is about 50-60cm (20-23 inches). This could be it.

My main problem is the smell from the collar. The pipe oozing is a brand new... feature. Might try a quick dirty fix with high temp tape as it's a bit higher. Just to isolate the smell problem. But will fix it in the long run.

The circle brick chimney body starts from the floor and goes all the way up. Metal pipes connects at top end. Also the old small pipe connects somewhere in the middle. Could there be cracks or bad masonry connecting they bodies which creates a lot of holes and the chimney actually sucks from them and not the pipe itself?

 

[kborndale]

The pipe is simple to fix, pull it off and flip it over. The fact that a brand new pipe has enough creosote in it to ooze like that is a bigger issue. Your burning habits need to change. 1.5 years seasoned wood can still be wet, especially depending on how it was seasoned (seasoning doesn't start until the wood is split AND stacked) and if your taking the dealers word about seasoning. Also some wood types like oak can take 2-3 years to season.

 

[St. Coemgen]

1) It's single wall very thick steel

Steel can get cold fast. Even if thick. And remember if is actually exposed to the outside air temp.

If you have a IR thermometer can you check the pipe temps all the way up. If it is "cold" at the top, then that may be an indicator of a problem.

2) I've tested all kinds of wood. It always smells from the collar/flange when high temp is reached. Despite cleaning stove and pipes thoroughly. Always... Currently using 1.5year seasoned hardwood.

It depends on the wood.
Ash can dry in 6 months.
Oak can take 2 or 3 years.
The only way to know is to use a simple two prong moisture meter on a fresh split wood surface. If you do not have a moisture meter, it is worth getting one.

My main problem is the smell from the collar.

Your pipe may need cleaning. A single walled pipe of that length I would clean 2 or three times a year myself. I have two stoves. My longest single walled pipe is 50 cm. Yet it generates, I would estimate, 15% of all the creosote I have. Between both my stove and chimneys (15 m total chimney height between two and they are both insulated chimneys), That is over an order of magnitude more creosote for that small section of single walled pipe per length. Interesting. But shows the different creosote issues one may have with insulated versus non-insulated flues.

Hope this helps.

 

[begreen]

Cold single-wall pipe, installed upside down. If the wood is not fully seasoned, it's a creosote producing trifecta.

 

[sourceless]

@St. Coemgen

1) Additionally in the room it rarely gets below 20C (68F). Also I don't go over 200C with the stove for a long time. But if I forget all air slots open and it gets pumped after 200C it starts smelling.

2) Tested the wood yesterday with a couple of samples I freshly split. It's between 20% or 30% depending on the type of wood. But I mainly use the 20% type. Here nobody burns aged wood, the neighbour has a similar setup 60cm horisontal pipe then horisontal about 4 meters. And burns only wet wood.

3) When I cleaned the pipes 90% of the creosote was in the short horisontal pipe and the 90% knee. I remember now reading somewhere that when you build a fireplace and design a chimney there should not be a section with less than 45% angle. Is that correct.

A pointer could be that when I disassembled the stove fully I cleaned it inside with a metal brush angle grinder. After that it still smelled from the collar when I pumped it up above 200C. Also when we lit it the first time (completely new chimney, new pipes) the stove smoked and smelled very aggressively. As if there is pressure inside searching all kinds of cracks to escape. As if the secondary burning chamber is creating pressure. (a the top of the stove. There are two stone plates)

4) Pipe temp: When stove top is at 200C
- the pipe next to it is about 180C,
- middle is 110C
- top horisontal is 90C but after passing the artificial wall of gipsokarton/plasterboard there is a gap until it reaches the bricks where it might be much colder.

The vertical pipe gens very little creosote.

Thanks for your inputs!

 

[30WCF]

As stated, the pipes are upside down. The male ends should point back towards the stove so anything dripping down the stove pipe stays contained within the pipe. You won’t leak smoke with a properly set up system even though it seems kind of counter intuitive. It’s the proper way to install stove pipe. Additionally, the lowest end of the pipe attached to the stove should be a male end inserted into the flue collar on the stove top. It looks at though you have a female end around the outside of the flue collar, which will leak and stink.
Flip it all around and don’t tape it.

Is the reason you burn low because you are trying to avoid the smell, or because of the comfort level in temperatures?

Fix the direction of the pipe first and then you can tackle the other issues.

 

[kborndale]

Just because lots of people burn wet wood by you (it happens here too) doesn't make it right. Dry wood burns easier, cleaner, and gives off much more heat saving you wood.

 

[Prometeo]

in addition to the suggestions given, your chimney on the roof, isn't it a bit too closed?

 

[30WCF]

I was having a hard time sorting out what chimney cap really looked like.

 

[begreen]

Just because lots of people burn wet wood by you (it happens here too) doesn't make it right. Dry wood burns easier, cleaner, and gives off much more heat saving you wood.

Most of the stoves I saw in Bulgaria were basic units, no secondary burn. I was staying at a small inn in Koprivshtitsa in the fall. Unlike many of the neighbors they had their wood all stacked and dried. They only burned dry wood. Others I noticed were splitting fresh wood. The second night there was cold and some folks were starting fires. This is in a mountain valley and it immediately filled up with smoke. What was a pleasant, clean air village, became gross overnight. The next morning we went to the local Internet cafe to confirm reservations at our next stop. There was a basic wood stove there too. It had a stack robber to boot. Clearances, pfft.

In another village I saw a trio of octogenarians cutting their firewood with a large, open blade saw operated by a foot treadle. It's an interesting and beautiful country where the old ways work side by side with the new.

Pics in this old thread

Some Euro heaters

Here are some snapshots of heaters I ran across while traveling. The first is a kacheloven room heater in Ukraine. The next is a small woodstove in a local internet cafe in Bulgaria. The last is a room heater, common in better homes in the mid 1800's in Bulgaria. In the room behind the stove...

www.hearth.com

 

[St. Coemgen]

[

Ah. Interesting information.

I will reply to out of order. As most relevant first.

4) Pipe temp: When stove top is at 200C
- the pipe next to it is about 180C,
- middle is 110C
- top horisontal is 90C but after passing the artificial wall of gipsokarton/plasterboard there is a gap until it reaches the bricks where it might be much colder.

I think there is a signigicant problem.

Water boils at 100°C. If your pipe is less than that, it is very likely the water in the exhaust gases are condensing on your pipe. And they run down, picking up soot and running out of your pipe connections. I am not even sure it is "creasote" then. Maybe just soot stained water.

Even wood at 10% moisture has some water in it. Thus you need to keep your flue hot enough to exhaust that water. 90°C is not hot enough.

What is interesting on this is your photos show the leaks at the top, where the pipe is "cool" not at the base. Which tends to support, without more detailed information, this current view of mine.

1) Additionally in the room it rarely gets below 20C (68F). Also I don't go over 200C with the stove for a long time. But if I forget all air slots open and it gets pumped after 200C it starts smelling.

Most stoves typically require to be run at 250°C to 350°C. You may be running your stove too cold. Running a stove too cold will mean more soot and creosote in the out gases, which you want to avoid. It can also prevent a hot enough gas to rise in the flue, especially if the flue is uninsulated and thus too cold to prevent condensation.

3) When I cleaned the pipes 90% of the creosote was in the short horisontal pipe and the 90% knee. I remember now reading somewhere that when you build a fireplace and design a chimney there should not be a section with less than 45% angle. Is that correct.

From your original photo, you have a 45° double bend pipe at the top. Not a 90° bend. I have a similar pipe connection, and it works fine.

Tested the wood yesterday with a couple of samples I freshly split. It's between 20% or 30% depending on the type of wood. But I mainly use the 20% type. Here nobody burns aged wood, the neighbour has a similar setup 60cm horisontal pipe then horisontal about 4 meters. And burns only wet wood.

What other people do is not necessarily relevant. Nuance is important. But wood stoves do need some basics, such as a good straight up chimney of at least 4 meters without any bends (taller is better), and a warm insulated flue. If you do not have this same height or more then that can cause issues. Your indoor flue is not insulated. That I think is a problem, especially for such a tall flue.

A pointer could be that when I disassembled the stove fully I cleaned it inside with a metal brush angle grinder. After that it still smelled from the collar when I pumped it up above 200C. Also when we lit it the first time (completely new chimney, new pipes) the stove smoked and smelled very aggressively. As if there is pressure inside searching all kinds of cracks to escape. As if the secondary burning chamber is creating pressure. (a the top of the stove. There are two stone plates)

If you disassemble a stove, then you can cause issues including breaking factory seals. Especially if you did very aggressive actions like using an angle grinder ... a very abrasive action, and not a good idea. You might have damaged the stove and made air leaks. But, overall, I doubt that is really the "problem". I am more and more thinking your problem is your too tall a single walled chimney in your house not getting up to a high enough temperatures.

I back tracked and looked again at your original post... And downloaded your stove manual. And looking at the manual, Appendix 4: Diagnosis diagram, most issues described are maybe fixable by correcting your chimney draft. Note the problems include issues like too cold a flue, which I think you definitely have.

Personally, I would lower your internal chimney. There is no reason to have it this tall. It does not heat the space more, and simply causes problems. There seems to be a blocked off flue pipe about half way up in one of your photos. I would unplug this, and would insert in your stove output there. If you can, I think many of your issues may end.

Side note: Despite many commenting on this, from North America, pipe direction does not mater in European stoves from the stove to the chimney connection. The male downward does matter in the main chimney flue, even in Europe. But in North America many stoves can be connected directly this way, straight line. But anyone in Europe knows, this type of direct stove connection is not normally done (especially on the Contient). It has less to do with draft, since any connection can be sealed, and more to do with rain water (which is why European chimney flues are separate from the stove linearlly, and have drain taps on the bottom).

Hope this helps.

 

[begreen]

All very good points. I would have a double-wall connector pipe in this case, but it does sound like the flue gases are too cool. In an odd way having the pipe installed upside down is warning of a bad condition inside. The reason for the crimps pointing down is so that the creosote drips into the stove and not down the outside of the pipe.

Water boils at 100°C. If your pipe is less than that, it is very likely the water in the exhaust gases are condensing on your pipe. And they run down, picking up soot and running out of your pipe connections.

If the temp is a surface reading, the interior flue gas temp is about double. Still too cool.

 

[begreen]

Looks like crimped end down is also followed in the UK

Black vitreous pipe always fits into stove “tapered end downwards”. In other words the male is on top inserting into the female below

How to connect your stove to your chimney liner using an adaptor

Black vitreous pipe always fits into stove “tapered end downwards”. In other words the male is on top inserting into the female below ;)

stovefitterswarehouse.co.uk

 

[St. Coemgen]

Most of the stoves I saw in Bulgaria were basic units, no secondary burn. I was staying at a small inn in Koprivshtitsa in the fall. Unlike many of the neighbors they had their wood all stacked and dried. They only burned dry wood. Others I noticed were splitting fresh wood. The second night there was cold and some folks were starting fires. This is in a mountain valley and it immediately filled up with smoke. What was a pleasant, clean air village, became gross overnight.

My local Hungarian village in Winter. Burning wood* usually bought that Autumn.

The air stinks and is not breathable...... Sad.

* Or other stuff... I have heard stories I can not confirm....

 

[St. Coemgen]

In an odd way having the pipe installed upside down is warning of a bad condition inside. The reason for the crimps pointing down is so that the creosote drips into the stove and not down the outside of the pipe.

I agree. Male down is better (it even prevents benign soot from dropping out). But in this case, I think a male down install might have hidden a more fundamental issue, and one that needs correction.

 

[sourceless]

Lol, never imagined I'd encounter so much support. Really appreciated, guys!

@30WCF the collar diameter of the stove is the same as the male pipe, I guess I need another collar flange?

I keep the temp at 200C top because of the smell. Could it be because of a feedback loop. I burn low because of smell which makes more creosote and cold flue. Makes sense?

Shall I insulate half of the inside flue, or the whole? For example with fire webbing like they do with tunned car exhausts, or something else?

Looking at this flue thermometer flue temp should be 150-250C ?

@Mirco22 Here are some pics from the roof. It's 23cm non-obstructed. Metal pipes are 15cm. Is it bad to increase diameter (slowing gases)?

Looks like a fire hazard a bit...

@St. Coemgen

Thus you need to keep your flue hot enough to exhaust that water. 90°C

So should I insulate the inner flue, or run the stove hotter?
Was thinking of running the stove on max for a couple of hours with doors/windows open to see if the smell will go away after a while. Worth a go?

Not a 90° bend. I have a similar pipe connection, and it works fine.

I meant there might not be a horizontal path in the flue.

breaking factory seals

Due to transport and being super heavy there were cracks in the silicone insulation everywhere. So smell was leaking from all sides. I grinded only flat surfaces where black matter was deposited.

Personally, I would lower your internal chimney

I can't. The rock wall has concrete at the back until the chimney bricks. The first possible entry is at the top.

There seems to be a blocked off flue pipe about half way up

This was the original exhaust, but is only 13cm and has quite a lot of turns until it reaches the chimney bricks. The smell problem was even worse with it. It was pretty cool that rocks and concrete acted like a temp battery, but still problematic.

Much thanks!

 

[sourceless]

Maybe try some of this as a quick test(rockwool with aluminium foil):

 

[Prometeo]

@sourceless
thanks for your additional photos,
the chimney is about ok,
I thought it was closed in the center too!
maybe you are a little at risk of incoming water when rain and wind.
I am writing to you from Italy
and initially I also had some drops coming down,
the cause was very damp wood.
Start investing in letting the wood dry well,
to measure it,
split a piece and measure internally.

 

[kborndale]

Before you start burning hotter fires I would sweep that chimney.

 

[30WCF]

Yep. A good cleaning is in order. Flip the pipe and get the proper adapter for the transition between the stove and stove pipe.
I may have missed it, what stove and brand of pipe is that? I have to have an adapter for my stove to pipe connection. This may not be the one for you, but this is the idea. A slight decrease in the male end side to fit the pipe and the stove.

 

[begreen]

Before you start burning hotter fires I would sweep that chimney.

Absolutely. There is a lot of creosote coating at the top. After that I would replace the stove pipe with double-wall stove pipe if available. And if possible, putting a 150mm stainless liner in the chimney.

Looking at this flue thermometer flue temp should be 150-250C ?

Yes

Maybe try some of this as a quick test(rockwool with aluminium foil):

That looks like fiberglass. Double wall stove pipe is better.

 

[St. Coemgen]

That looks like fiberglass. Double wall stove pipe is better.

Not fiberglass which is combustible. This is rock wool AKA mineral wool.

Double wall stove pipe is better.

Double walled, as in an EU style of pipe, I agree, in this case may be needed.

That is, do be aware that in the EU, "double walled" pipe is always insulated pipe, with rock wool. There is no air cooled double walled pipe like in North America here that I am aware of. And being usually stainless both in and out, it is quite expensive.