RAIS GEO, User Manual

ENGLISH                            RAIS - manual for GEO                                                        

7

Chimney

The chimney is the driving force which makes the stove function. In order for the stove to 
perform satisfactorily the chimney height must be sufficient to ensure the correct draught 
of 14 to 18 Pa so as to clear the products of combustion and prevent problems of smoke 
emanating into the room when firing.
NOTE: A chimney height of not less than 4.5 metres measured vertically from the outlet 
of the stove to the top of the chimney should be satisfactory. Alternatively the calculation 
procedure given in BS 5854:1980 may be used as the basis for deciding whether a particular 
chimney design will provide sufficient draught.

The outlet from the chimney should be above the roof of the building in accordance with the 
provisions of Building Regulations Approved Document J.

If installation is into an existing chimney then it must be sound and have no cracks or other 
faults which might allow fumes into the house. Older properties, especially, may have chim-
ney faults or the cross section may be too large i.e. more than 230 mm x 230 mm. Remedial 
action should be taken, if required, seeking expert advice, if necessary. If it is found necessary 
to line the chimney then a flue liner suitable for solid fuel must be used in accordance with 
Building Regulations Approved Document J. 

Any existing chimney must be clear of obstruction and have been swept clean immediately 
before installation of the stove. If the stove is fitted in place of an open fire then the chimney 
should be swept one month after installation to clear any soot falls which may have occurred 
due to the difference in combustion between the stove and the open fire.

If there is no existing chimney then either a prefabricated block chimney in accordance with 
Building Regulations Approved Document J or a twin walled insulated stainless steel flue to 
BS 4543 can be used. These chimneys must be fitted in accordance with the manufacturer’s 
instructions and Building Regulations.

A single wall metal fluepipe is suitable for connecting the stove to the chimney but is not 
suitable for using for the complete chimney. The chimney and connecting fluepipe must 
have a minimum diameter of 150 mm and its dimension should be not less than the size of 
the outlet socket of the stove which is 150 mm in diameter. Any bend in the chimney or con-
necting fluepipe should not exceed 45°. 90°bends should not be used.

Combustible material should not be located where the heat dissipating through the walls 
of fireplaces or flues could ignite it. Therefore when installing the stove in the presence of 
combustible materials due account must be taken of the guidance on the separation of 
combustible material given in Building Regulations Approved Document J and also in these 
stove instructions.