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I have an open fireplace. I have done tubing lately: Diam.: 16mm. Since then, she has been smoking a lot and I raised the focus of 10 cm to avoid it: it works, but it makes tar (a lot). I burn oak which is normally dry, but the tar always comes out from the top of the pipe. How to get rid of tar?

The presence of tar simply reveals a bad draft. It is possible that the chimney outlet is too low (it must exceed 40 cm), or that the casing has excessively reduced the duct section. A pinch of it is also possible. Ask the heating engineer who installed the duct for a check. Make sure that no external parasitic element has disturbed the natural draft of the chimney (installation of insulating window, VMC, new kitchen hood, etc.).

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