The subject of the Sweep safe Technical update is type one and type two smoke testing.
The two tests serve very different purposes and must not be confused with each other.
Although you will find this guide very useful it does not supersede the process set out in building regulations section j and we highly recommend you take the time to study the document.
A type one test is a sealed test designed to check for unacceptable leakage where as a type two test is designed to check for draught and adequate smoke evacuation. It is this type two test or variations of that we perform at the end of every sweep and document on the certificate.
Let’s first look at what is required to perform the tests. We are using:
Type two smoke test
Firstly we close all door and window in the room of the appliance, we also close any closable air vents.
If there are extractor fans we turn them on full power and wait several minutes to make worst case scenario conditions
Next we preheat the flue for 10 Minutes.
After the flue is heated an up draught is formed, place one smoke pellet in the burning area inside the cup and ignite it at arm’s length wearing a glove.
We close the door of the appliance if it is designed to be used with the door closed.
Initially we check around the appliance to check for spillage or a weak or slow up draught, if the draught is weak or slow. Next open an external window to see if the smokes velocity increases. If it does this demonstrates that the ventilation is inadequate.
Next proceed outside to a pre-determined position and view the pot and chimney stack using our binoculars and check for the complete evacuation of the smoke.
The smoke must issue from only one chimney pot or terminal, the same pot or terminal as the sweeping brush was associated with.
Binoculars are essential for smoke testing
If smoke is seen from more than one pot or smoke is seen leaking from the stack, rafters or anywhere else then this is a fail as it shows leakage. In essences we are checking to see that all of the smoke goes in one end and out the other without deviation. Any accessible parts of the chimney should be visually inspected.
A failed smoke test would trigger a warning notice and do not use label being issued in most instances.
It can be difficult to see white smoke on a cloudy day.
Type one testing
Firstly it is imperative that you have adequate working at heights training, equipment and have a safe working platform in order to access the terminal. You also require a second person for safety and for igniting the pellets below.
Most importantly you will be giving safety advice when performing this test and as such require professional indemnity insurance to protect yourself and your business.
We close all door and window in the room of the appliance
Preheat the flue for 10 Minutes.
Place two smoke pellets in the burning area inside the cup or flame proof container and ignite it at arm’s length wearing a glove. We advise adding one smoke pellet per additional floor of the property.
We allow to smoke to rise to the chimney terminal and then, before it escapes seal it using a bung, sponge or taped bag.
Quickly we must also seal up the aperture or appliance opening locking the smoke inside.
As the smoke is hot it continually expands and tries to escape. We must check the entire length of the chimney system and check for leakage for a minimum of five minutes.
Any leakage inside if the dwelling would constitute an immediate fail and trigger advice to repair or reline given and a warning notice raised.
If there is very minor leakage to outside via the stack it is difficult to judge a pass or a fail without significant experience, however it is usually best practice to air in the side of caution and if smoke is clearly visible leaking then the diagnoses would be a fail.