Regarding blocking up
chimneys for a CWI measure,
there is a concern that where
there is residue of soot left
in the chimney and a lack
of ventilation if the balloons
are used, this can potentially
cause sulphur and condensation to react
and eat away at the brick. Thus, what would
you advise with blocking chimneys up,
reducing this risk, and installing background
ventilation?