What should never be done to a blocked passage in a chimney?

Pounding from above with a weight is not a safe or effective method for dealing with a blocked passage in a chimney. This action can cause damage to the chimney structure as well as create additional hazards by potentially dislodging debris that might fall unpredictably. Chimneys are designed to safely ventilate smoke and gases; forcing a blockage from above can lead to structural issues or further obstruction.

In managing a blocked chimney, it is essential to approach the obstruction with care. The other options, such as applying heat or forcing air from below, can involve risks including fire hazards or causing more significant damage. Leaving the blockage unattended could also allow for worsening of the situation, including the possibility of hazardous gases being trapped or exacerbating any underlying structural issues.

Therefore, the most reasonable and safe practice is to refrain from using a weight to attempt to clear the obstruction. Instead, professionals often recommend inspecting the blockage and addressing it through proper cleaning procedures or remediation techniques.