Creosote smell and pipe oozing

[St. Coemgen]

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?

Yes, that I think is part of the issue.

But I think the issue is that your chimney is not giving you enough draft. That is, I think you have a cold chimney. Again, from your stove manual it stated you need an appropriate insulated chimney.

Is the top of your chimney new, insulated and of the correct diameter? If not, than if you have a too large or too small diameter, and if the chimney is cold, then you get no draft up the chimney and the smoke of your fire simply leaks out of the pipe and around the stove.

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?

Yes. And run it hotter when you do.

This may be an unpleasant experiment, but I would suggest running your stove hot enough to get your upper stove pipe between 200°C and 250°C outside temp**. That should also heat up your main chimney. It may stink before that temp. But the question is... does the stink go away when you get your flue to a good working temperature?

**Edit: After posting this, I started to think if you have an otherwise old main chimney... that may be too hot. The goal is to heat up your main chimney to give you draft till you do not have smell issue. That may happen at maybe lower than 200°C on your outside pipe temp. You may actually need to experiment to be safe with an old flue.

If so, than your problem is a cold flue. You need to correct this by insulating your flue.

If the smell persists... let us know.

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

What matters is the temp of the surface of the pipe and time contact of the gas.

Even super heated steam will condense on a cold surface. The colder the surface, the more condensation. This is why steam engines have drains on the cylinders, to prevent hydraulic lock as hot steam condenses on cold cylinders at start up.

You can also see this, in a way, if you boil water in a pot with a glass lid. The glass lid may be good and hot, touch it and you will burn your fingers, but steam will will still condense on the inside of the lid. The lid is hot, but still cool enough to cause condensation

Of course both examples are "closed systems" to some extent (tilt the lid a bit on the pot and the steam can escape before condensing), but if you do not have good draft, then your pipe may function in some ways as a closed system and you get more than normal condensation.

Here are some pics from the roof. It's 23cm non-obstructed.

Pics not visible. But if the flue is 23cm wide, that is way too wide. That can definitely cause a cold flue. Resulting in poor draft and back drafts, and pushing smoke back down toward the stove, where it can leak out and smell.

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

Typically the horizontal path should be less than 50 cm. If longer, it can cause reduced drafts, which also may an issue.... Solution would then to move your stove closer to the wall and shorten your horizontal path.

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.

Any chemical sealant is typically special fire mortar. I do not know if they are silicone based. My stoves do not use any sealant for seams. All dry fit. Can not competently comment on sealant issues.

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

Ah. Well, then you have to work with what you have.

Or else tear down the chimney and put in a modern, ceramic, insulated chimney. I do not suggest this lightly. It can be expensive. But it is what I did. Twice (we have two chimneys). Since both of my chimneys were brick, old, square interiors, not insulated and stank, it was simply easier to get new modular insulated Schiedel chimney kits and rebuild them.

Hope this helps.