Chimney Smoke Tests
Chimney Smoke Tests in London, Hertfordshire & Essex
If you don't know the history of your chimney, maybe you've just moved in, or you're reopening a fireplace that's been out of use for years, you need to know whether the flue is airtight before you start using it. A chimney smoke test checks exactly that: is the chimney going to keep dangerous gases where they should be, or is something leaking into rooms above or into a neighbouring property?
SweepSmart carries out chimney smoke tests and pressure tests across London, Hertfordshire and Essex. We use specialist equipment alongside standard methods to give you a definitive result, not a best guess.
Two Types of Chimney Smoke Test
This is worth understanding because the terminology causes confusion
Smoke Test 1 (Leakage Test)
Smoke Test 1 is a separate, more thorough test. Smoke pellets are lit inside the fireplace, the terminal and opening are sealed, and the full length of the flue is visually inspected for leaks. The tester needs access to all floors including loft spaces, and in shared properties, adjacent flats as well.
The important thing to know is that a standard Smoke Test 1 has limitations. It's subjective. It relies on the tester spotting the leak visually, and some leaks are too small to see. That's why we combine it with specialist pressure testing equipment.
Smoke Test 2 (Evacuation Test)
Smoke Test 2 is the test your chimney sweep carries out as standard during a routine sweep. It checks that the chimney will evacuate gases freely, that the draw is working and smoke goes up and out. It does not test for leaks. This is included with every SweepSmart sweep.
Why We Use Pressure Testing Equipment?
We use a Wöhler DP600 testing device alongside the smoke pellet test. Air is pumped into the flue and the device measures exactly how much, if any, is leaking out. It produces a reading of the allowable leakage rate versus the actual leakage rate, giving you a definitive pass or fail.
The advantages are significant. The terminal can be sealed from the ground using a specialist bladder, so no roof access is needed. There's no need to access other floors or neighbouring properties. It eliminates the possibility of human error and produces a signed printout of the result. This method (BSEN 1443) is the recognised European standard for flue testing. In many countries, smoke-only integrity tests aren't even permitted.
The chimney is always swept before any test, as debris can conceal small cracks. Sweeping also allows us to measure the chimney height, which we need to calculate the test result.
When Would You Need a Chimney Smoke Test?
The most common situations include: the history of the chimney is unknown because you've just moved in or reopened a fireplace, you suspect smoke may be leaking into other rooms or properties, a neighbour has reported fumes leaking into their home, you're installing a new appliance and the flue must be tested before a change of use, the appliance hasn't been used in over three years, a party wall agreement requires testing before and after building works, or you're experiencing persistent problems with your flue.
If you need a more comprehensive assessment that includes smoke testing alongside a full CCTV inspection and pressure test, a Level 2 Chimney Inspection may be the better option.
How Long Does a Chimney Smoke Test Take?
A standalone smoke and pressure test typically takes around 60 to 90 minutes per flue, depending on the chimney. We'll confirm the timings when you book.
Need to find out whether your chimney is safe to use? Book a smoke test. We'll give you a definitive answer, not a best guess. Over 1,000 five-star reviews across London, Hertfordshire and Essex.
FAQs
What's the difference between Smoke Test 1 and Smoke Test 2?
Smoke Test 2 is a draught test — it checks the chimney evacuates gases freely. It's included with every standard sweep. Smoke Test 1 is a leakage test — it checks whether the flue is airtight by sealing the chimney and looking for smoke escaping into other rooms or properties. They test completely different things.
Why do you use pressure testing equipment as well as smoke pellets?
Because a standard smoke pellet test has limitations. It's subjective — it relies on the tester spotting leaks visually, and some leaks are too small to see. The Wöhler DP600 pressure testing device pumps air into the flue and measures exactly how much is leaking out, giving you a definitive pass or fail rather than a best guess.
When would I need a chimney smoke test?
If the history of the chimney is unknown, you've just moved in, you're reopening a fireplace that's been unused for years, you're installing a new appliance, a neighbour has reported fumes, or a party wall agreement requires testing before and after building work.
Do you need to get on the roof for a smoke test?
Not with the pressure testing equipment. The Wöhler DP600 seals the terminal from the ground using a specialist bladder — no roof access needed. This also means we don't need access to other floors or neighbouring properties for the pressure test portion.
What happens if my chimney fails the smoke test?
The chimney must be lined before it can be used safely. There are different lining methods available depending on your appliance and the chimney's construction. We'll review the findings with you and discuss the most suitable option.