Hergom H-01 Instrucciones Para La Instalación, Uso Y Mantenimiento página 33

g) It is very important that the chimney should be one metre higher
than the highest part of the house. If you need to increase the
draw, extend the length of the chimney.
.
h) Chimney covers must not affect chimney draw.
i) Clean the chimney at least once a year.
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