The most expedient chimney section is cylindrical because the smoke moves spirally, and then square and at last the most inopportune is rectangular.
The chosen section form of the channel should follow throughout all its height; narrowing and turns can spoil all business.
Old house chimney
Wide chimneys still possible to meet in old houses, they have bad draught-out power and demand the big fuel consumption.
They may be corrected by the next ways:
- Take apart the top part and construct the new, narrower chimney or install on it fibrocement extension.
- Other way in an old chimney attaches a new chimney from a stainless steel pipe.
The length of a pipe needs to be defined experimentally; sometime 7 feet will be enough. The new chimney it is not necessary to install on all height of an old chimney. And do not forget about a demountable casing for soot removal in the bottom part of a chimney.