hergom CRETA Instructions D'installation, De Service Et De Maintenance page 28

f) It is vital that the joins in the pipes are correctly sealed so that any
possible cracks, which could allow air to enter, are covered.
Incorrect
To test the chimney to ensure that it is air and water tight proceed as follows:
- Cover the outlet in the roof.
- Put paper and damp straw in the lower part of the chimney and light them.
- Observe any possible cracks through which smoke is escaping and seal them.
g) It is vital that the chimney is at least one metre higher than the
highest part of the house. If the draft needs to be increased the chimney must be
higher.
Incorrect
Correct
Fig.-7
Covering slab
Escaping smoke
(Seal)
Paper and
damp straw
Fig.-8
At least
1 metre higher
Incorrect
Correct
28
Correct