1, flue, kang surface sealing is not good or chimney height is not enough, resulting in reduced chimney suction, resulting in smoke and fire.
2. If the flue is not smooth or the cross section of the chimney is too small, the flue gas cannot be discharged smoothly when the stove is burning, which will also cause the flue gas to flow backwards.
3. It used to be said that "seven rows of pots and eight rows of kang" means that the whole combustion smoke exhaust system should have a certain slope.
I suggest you find a bricklayer with experience in "walking around the kang" to check and repair it.