Smoke testing chimneys
Chimney Pressure - Smoke Test 1
The chimney pressure test is a pressure smoke test to check the air tightness of the chimney. Chimney pressure smoke tests are required when installing a new appliance into an existing chimney or reopening a chimney following a house move. This service is popularly used if smoke is suspected of leaking into the property or part of an adjacent building.
Once the flue has been warmed, a number (based on the flue size) of smoke pellets are placed in the fireplace. Once the smoke can be seen at the top of the chimney, the chimney pot is closed or sealed. While the smoke is contained within the chimney breast, several inspections are performed and the chimney structure is investigated in great detail to ensure that the flue is sufficiently airtight. Any smoke seen evacuating from parts of the chimney will indicate a failure.
Chimney Draw - Smoke Test 2
The chimney draw test checks the ventilation in the room to ensure the chimney is evacuating smoke freely.
This smoke test should determine whether there is enough ventilation in the room to ensure the chimney is evacuating all products of combustion freely. Although this test can identify leaks, it’s not a test to determine whether a flue is airtight. The difference is the top and opening are not sealed during the test, hence not creating pressure that would identify leaks. This smoke draw test is performed after every sweep, servicing an appliance, and commissioning a new installation.
During the chimney draw test, all doors and windows in the room are closed and the flue is warmed. After 10 minutes, a smoke pellet is lit in the fireplace. The smoke is observed for any leakage back into the room and a door or window is opened to see if the additional ventilation speeds up the smoke. The smoke is then observed evacuating from the top of the chimney.