hergom H-01 Instructions D'installation, De Service Et D'entretien page 32

e) The internal walls must be perfectly smooth and free from
obstacles. Avoid bottlenecks where pipes join to the brick
chimneys.
f) It is very important to ensure that the joints of the pipes are well
sealed to avoid possible cracks through which air may enter.
In order to verify the air-tightness of the chimney, you may:
- Cover the outlet on the roof.
- Introduce damp paper and straw at the bottom of the chimney and
light it up.
- Watch for possible cracks through which smoke leaks out and seal
them.
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