1.8 Connecting to a steel chimney
If your installation involves taking the chimney straight up and through the ceiling, you must
comply with National, Local Building Regulations or flue manufacturers instructions concern-
ing clearances to combustible materials such as walls, floor joists and ceilings. The joint be-
tween the stove flue collar and the stovepipe must also be sealed using the glass fibre rope
provided. It is important that the insulated flue system is properly supported both at ceiling
level and at roof level.
THE STOVE MUST NOT BEAR THE WEIGHT OF THE CHIMNEY SYSTEM (See chimney manu-
facturer’s instructions). Excessive weight on the stove will inhibit expansion and could lead to
damage of the stove top. Damage caused to the stove in this way would not be covered by the
manufacturers guarantee.
If a chimney fire should occur as a result of incorrect operation of the stove or prolonged use
of wet fuel, close the vents completely and contact the fire brigade.
1.9 Draught
If smoke comes out of the stove when the fire door is opened, it will be due to the poor
draught in the chimney. This type of stove requires at least 12 PA of chimney draught to
achieve satisfactory combustion and to prevent smoke from escaping. Smoke may, however,
escape in any event if the stove door is opened during vigorous firing, so this should be
avoided.
The flue gas temperature at the rated output is 281°C relative to 20°C.
If in doubt, you may want to get your chimney sweep to measure the draught in the chimney.
Be aware of the following:
Discuss the cleaning options with your chimney sweep.
If there is insufficient draught in the chimney, it may be a good idea to install the
flue pipe straight up so as to minimise smoke migration in the actual combustion
chamber.
Avoid having more bends than necessary, and limit the length of the flue pipe so as
not to reduce the draught.
Fresh air supply
A wood-burning stove requires air for combustion. As a result, firing a
wood-burning stove will help create a healthy climate in your house. If the house is
very tightly sealed, and particularly if there is a cooker hood or ventilation system
in the house, it may be necessary to install an air grate in the room in which the
wood-burning stove is installed. Otherwise there may not be enough draught in the
chimney, which may result in the stove not being able to burn properly, and smoke
may come out of the stove when the fire door is opened.
If it is necessary to install air grates, they must be positioned so that they cannot be
obstructed.
Draught
The draught in the chimney is the result of the difference between the high
temperature in the chimney and the cooler temperature outside. Other factors that
determine whether sufficient negative pressure can be produced to create a draught
include the length and insulation of the chimney, and wind and weather conditions.
The draught will be reduced when:
- The temperature difference is too low, e.g. in connection with a poorly insulated chim-
ney.
If the chimney is cold, it may help to light (burn up) a rolled-up newspaper in the
chimney’s cleaning door.
- The outside temperature is too high, e.g. during the summer.
- There is no wind.
- The chimney is not tall enough, with the result that it sits in the lee of the roof sur-
face or tall trees.
These conditions are also associated with the greatest risk of smoke coming back
down the chimney.
- Air is entering the chimney in undesired places, e.g. through cracked joints or leaks
in the cleaning door or the flue pipe.
- Unsealed, unused fireplaces are connected to the chimney.
- The flue pipe and chimney are clogged up with soot due to inadequate cleaning.
- The house is too tightly sealed (please see the section on Fresh air supply).
A good draught is achieved when:
- There is a big difference between the temperature in the chimney and outside, i.e.
when the need for heating is greatest.
- The weather is clear and there is a good wind.
- The chimney is of the proper height, i.e. Minimum 4 metres above the stove, and clear
of the spine of the roof.
To Next Page
Loading...
