Smoke Test Guide
These are two Primary purposes for smoke testing, the first test is to discover any major
defects which can cause leakage of fumes through a chimney or flue structure during normal
operation. The second is to test the draw in the appliance.
If in doubt about the condition of a chimney, especially when an old chimney is to be used
after a long period of being unused, it is recommended to have it smoke tested. This is
particularly relevant for chimneys constructed prior to the 1965 Building Regulations which
require all new chimneys to be built with a suitable flue liner to protect the chimney
structure . Smoke Testing should also be carried out during construction of traditional
masonry chimneys and on all completed chimney installations.
A smoke test should be done by a competent person using the following procedures which
are based on recommendations in British Standard BS5440-1:2008. A slightly different
procedure is required for testing flues for gas appliances.
It should be remembered that the pressure of smoke from a test is far greater than that of a
chimney during normal use. Consequently minor smoke leakage may occur in joints of a
traditional masonry chimney or connections between prefabricated metal chimneys and flue
pipes. Minor leakage detected should not be a major risk when the appliance is used,
providing that it does not indicate a fault that could get worse. Remedial work will be
required if heavy leakage is seen. The most likely problems are broken components,
incorrect fitting or incomplete joining of flue liners.
Smoke Test 1: Testing Air Tightness of Chimney
•
Ensure appliance is not alight and all doors and windows in the room are closed.
•
If there is a solid fuel appliance or open fire appliance fitted at the base or the bottom
of the chimney, heat the inside of the Appliance/Fireplace chamber with a blow Lamp,
gas stove or similar device for approx 10 minutes, a longer warming up time may be
needed with wet or cold flues. This will establish a flue draw to stimulate real
conditions. It should be realised that neither of these methods create the same
temperatures or volume of hot gases that would normally be created whilst the
appliance is in use. If the flue is to be used with a gas burning appliance, the smoke
test should be carried out before the fire is fitted and the flue warmed with a blow lamp
for only 5 minutes, or longer if the flue is cold.
•
For testing flues to be used with a solid fuel appliance place one smoke pellet with a
minimum burn time of 60 seconds producing 15 Mtr
3
of smoke on a flat surface that
cannot be harmed by heat in the opening at the base of the flue or in the appliance if it
is fitted. Always follow the pellet manufacturer’s safety instructions.
•
Ignite the top edge of the pellet and when smoke appears seal the opening with a board
or plate sealed at the edges. If a solid fuel appliance is fitted, close all doors, ash
pit covers and vents. Do not seal off the base of the flue or opening if testing a flue for
a gas appliance.
•
Check that the smoke rises freely out of the correct flue. When smoke begins rising
out of the top of the chimney, seal the top of the flue, terminal or pot, if appropriate
use an inflated football, bladder or plastic bag sealed in position with tape. Do not seal
the top of the flue if it is to be used with a gas appliance.
•
Examine the full length of the chimney for any leakage of smoke such as the joints for
metal flues. If possible check for signs of leakage from wall cavities at the sides and
back of the chimney, if it is built into a wall, also check for leakage at openings around
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