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How to smoke test a chimney

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Smoke testing a chimney (for leaks)

warming the flue, burning kindle, smoke test, how to perform a smoke test, chimney flue

Step 1 – Warm flue

Light some paper or kindling and let it burn in the grate for 2-3 minutes to warm the flue and establish a draw (air flow). A longer time may be needed with cold or wet flues.

If there isn’t a grate, use a blow lamp for about 10 minutes to establish a draw. Warming the flue is very important as this will improve the draw of the chimney and produce more accurate smoke test results.

warming the flue, chimney flue, blow lamp, smoke testing a flue It is important to warm the flue even in summer months as the air is at a different density and may stop your chimney drawing up the smoke.
lighting the smoke pellets, smoke test, chimney flue

Step 2 – Place smoke pellet in chimney and set alight

Place a smoke pellet (or two) in the opening of your chimney flue. The precise number of pellets needed may vary depending on the size of your smoke pellets, the volume of smoke they create, and the dimensions of your chimney flue.

Ignite your pellets with a lighter or match.

smoking pellets in fireplace, smoke testers, smoke test, chimney flue

Step 3 – Cover opening

When they begin to smoke, cover the flue opening with a board or plate which can be sealed at its edges (if an appliance is fitted to the chimney flue, close the door, ash pit cover and any vents).

smoke tester, smoke rising from chimney

Step 4 – Cap flue

When the smoke reaches the top of the flue and begins rising from the chimney top, cap the top of the flue. (This can be done by simply laying a board over the top. Just remember to remove it when you have finished!)

Chimney inspection diagram

Step 5 – Inspect chimney

Examine the full length of the chimney and any adjoining rooms for any smoke leaking from it.

Smoke test, smoke filled room, leaking chimney

Step 6 – Correct any defects

If, at any point smoke is detected, establish the point of origin and correct any faults or defects.

Fix chimney leaks, defects, smoke test

Step 7 – Repeat test

After fixing any leaks or defects, repeat the testing until no more leakages are apparent.

Smoke test, remove covers from chimney

Step 8 – Remove covers

Remove the closures from the top and bottom of your chimney.

Smoke testing a chimney (for draw)

warming the flue, chimney flue, blow lamp, smoke testing a flue

Step 1 – Warm flue

Warm the flue for several minutes with a blow lamp to establish a draw.

This is important to do because a cold flue may not draw very well and you might misinterpret this as a blockage or defect. Give the chimney the best chance to draw.

Smoke testing. close windows and doors

Step 2 – Close all doors and windows

Close all the doors and windows in the room so that no draughts will affect the outcome of the test.

smoke test, lighting your smoke pellet

Step 3 – Light smoke tester

Light a smoke tester, match, or pellet and place it in the chimney grate.

smoke test, smoke drawing up chimney

Step 4 – Is the smoke drawn up?

When the smoke pellet begins to smoke, watch to see if the smoke is drawn up the chimney flue. If the smoke rises up quickly then your chimney is drawing well.

smoke testing, chimney half drawing

Step 5 – How fast is the smoke drawn up?

If the smoke is drawn up the chimney but not very rapidly then your chimney is drawing but not very well. Your flue may be partially obstructed and needs to be remedied.

smoke testing, smoky fireplace, chimney not drawing

Step 6 – Fix any defects

If the smoke does not get drawn up the flue and instead billows out into the room, then your chimney is not drawing at all and you will need to fixed any obstructions or defect before it can be passed for safe use.

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