Camera inspections
& flue testing
Clear professional checks for the condition, operation and integrity of chimneys, flues and solid-fuel appliances.
BOOK AN INSPECTION →These checks answer three separate questions.
A camera inspection, an appliance spillage test and a flue smoke-integrity test are not interchangeable. The correct check depends on what needs to be confirmed.
Camera inspection
Looks inside the flue for visible damage, deposits, obstructions and suspect joints.
APPLIANCE OFFSpillage test
Checks whether combustion products spill into the room while the appliance is operating.
APPLIANCE UNDER FIRESmoke Test I
Checks the complete flue route for significant smoke leakage with both ends temporarily closed.
APPLIANCE NOT UNDER FIREA clear view inside the chimney or liner.
A chimney camera helps us examine areas that cannot be seen from the fireplace. It can help locate and record:
- Nests, debris or other obstructions
- Heavy soot or tar deposits
- Changes in the size or direction of the flue
- Damaged masonry, liner surfaces or displaced sections
- Joints or areas that need further investigation
Spillage testing
APPLIANCE UNDER FIREThe test answers a simple question: when the appliance is alight, are the combustion products travelling safely into the flue rather than spilling into the room?
What is checked?
- The appliance and its connection to the flue
- Permanent ventilation and available air supply
- Draught and likely spillage points around the appliance
- Possible restrictions or termination problems
- Pressure effects from mechanical extract systems elsewhere in the property
What happens if spillage is found?
Any confirmed spillage must be investigated and corrected. The appliance should not be regarded as safe to use until the cause has been remedied and the installation has passed the appropriate retest.
Technical Booklet L says a spillage test should be carried out with the appliance under fire. It points to BS EN 15287-1 Annex O for a suitable solid-fuel test procedure.
Flue smoke-integrity test — Smoke Test I
APPLIANCE NOT UNDER FIRESmoke Test I checks whether the complete flue route is acceptably gas-tight. It is a separate test and does not replace the appliance spillage test.
How the test is carried out
- 1Sweep the existing flue
Soot, tar and debris are removed first so the condition of the flue can be properly assessed.
- 2Establish a draught
With the appliance not under fire, the flue is warmed and suitable flue-testing smoke pellets are lit at its base.
- 3Close the bottom
Once smoke forms, the appliance or fireplace opening is closed and sealed so the smoke can enter only the flue.
- 4Check the correct terminal
Smoke must first issue freely from the correct chimney outlet. The terminal is then temporarily sealed.
- 5Inspect for leakage
The accessible flue route, nearby spaces and other chimney outlets are checked for significant leakage for at least five minutes.
- 6Remove the seals and report
The top and bottom are reopened. The findings and any required remedial work are explained before the flue is used.
Correct smoke quantity, temporary sealing, safe access to the terminal and interpretation of the result all require competent judgement. Technical Booklet L notes that smoke pellets create more pressure than a natural-draught flue normally experiences, so any visible leakage must be assessed for significance.
Smoke can emerge some distance from the actual defect.
Deteriorated mortar, failed liner joints, cracks or concealed damage can let smoke travel through the building before it becomes visible.
Around the outside of the chimney where it passes through the loft, particularly near old joints and repairs.
At gaps, joist pockets, ceiling edges or concealed floor and ceiling voids.
Through failed brickwork, cement joints or unfinished openings around the chimney breast.
Smoke at another chimney outlet indicates leakage between flues. Properties sharing the chimney stack may also need to be checked.
Where building work exposes the chimney, the test should ideally be carried out before plaster or dry lining hides the surfaces.
Black soot staining should be investigated.
Soot marks near skirting boards or on a chimney-breast wall
This may be consistent with flue leakage or historic contamination. It does not prove where the fault is, because smoke and soot can travel through concealed voids and staining can have other causes.
Smoke or soot in roof and floor spaces
Marks, odours or visible smoke around concealed parts of the chimney require investigation before the flue is used.
Existing and modern chimney systems
Brick or stone flues, including an existing fireplace being considered for use by a new homeowner.
Clay liners, ceramic liners and flue-block systems where cracks or failed joints may be concealed.
Flexible liners are inspected and tested using methods suitable for the system. A coring ball must not be used in a flexible liner.
Factory-made metal chimney systems, their joints and accessible concealed routes.
Do not use it until it has been repaired and retested.
- 1Stop using the flue
The appliance or proposed fireplace should not be brought into service.
- 2Locate the likely defect
Camera evidence, the smoke location and the chimney construction help guide further investigation.
- 3Complete the remedial work
This may involve joint or masonry repairs, reconstruction, connection corrections or fitting a correctly specified new liner.
- 4Retest before use
The relevant integrity and appliance tests are repeated before the flue is returned to service.
A new chimney liner is often the practical remedy.
This is particularly true where an older masonry or clay-lined chimney has widespread deterioration or inaccessible leaks. It is not automatically the only solution; the correct work depends on the appliance, fuel, flue construction and location of the defect.
Northern Ireland Technical Booklet L
Appendix A covers inspection and testing of natural-draught flues. It requires an existing flue to be swept before smoke testing, describes Smoke Test I for solid-fuel flues, sets a minimum five-minute inspection period after the terminal is sealed and confirms that smoke testing does not replace spillage testing.
Unsure which inspection or test you need?
We can recommend the correct check for your appliance, chimney and concern.