If connecting to a chimney a steady draught of
between 0.04 and 0.06 inches W.G. is required.
When a draught recorded is over 0.06 inches W.G. a
stabiliser must be fitted.
DOWN DRAUGHT
However well designed, constructed and positioned,
the satisfactory performance of the flue can be
adversely affected by down draught caused by near-
by hills, adjacent tall buildings or trees. These can
deflect wind to blow directly down the flue to create
a zone of high pressure over the terminal.
A suitable anti-down draught terminal or cowl will
usually effectively combat direct down draught but
no cowl is likely to prevent down draught due to a
high pressure zone. (See fig. 5)
USE OF EXISTING FLUES AND CHIMNEYS
When connecting to an existing chimney it is neces-
sary to line the flue using either 5” (125mm) rigid or
flexible stainless steel flue liner.
An existing flue pipe or chimney that has proved to
be satisfactory when used for solid fuel can normal-
ly be used for this appliance provided that its con-
struction, condition and dimensions are acceptable.
Flues that have proved to be unsatisfactory, particu-
larly with regard to down draught, should not be con-
sidered for venting this appliance until they have
been examined and any faults corrected.
Before connecting this appliance to a chimney or
flue pipe which has previously been used with
another fuel, the chimney or flue pipe should be
thoroughly swept.
All register plates, restricter plates, damper etc.
which could obstruct the flue at a future date should
be removed before connecting this appliance.
Where a chimney is not to be lined a suitable void
should be provided at the base to contain any debris
which might fall from the inside wall, so as to prevent
that debris from obstructing the appliance flue outlet.
(Removal of debris should be facilitated by the pro-
vision of an access door). This void should have a
depth of not less than 250mm (10”) below the appli-
ance connection.
The combustion products on any oil burning appli-
ance will have a descaling effect on hardened soot
deposits left from burning solid fuels.
ALTHOUGH THE CHIMNEY MAY HAVE BEEN
CLEANED OF LOOSE SOOT PRIOR TO INSTAL-
LATION, IT IS IMPERATIVE THAT THE CHIMNEY
IS INSPECTED FOR SCALED SOOT PARTICLES
AFTER THE FIRST MONTH OF OPERATION AND
ANY LOOSE MATERIALS REMOVED TO AVOID
BLOCKAGE.
FACTORY MADE INSULATED CHIMNEYS
Factory-made insulated chimneys should be con-
structed and tested to meet the relevant standards
and recommendations given in:
*
B.S. 7566 - Installation of factory-made
chimneys conforming to B.S. 4543 for
domestic appliances.
*
Part1: Method of specifying installations
design information.
*
Part 2: Specification for installation design.
*
Part 3: Specification for side installation.
*
Part 4: Recommendation for installation
design and installation.
Fig.5
9
