Is my flue suitable for a woodburning or multi-fuel stove?

When installing a wood burning or multi-fuel stove, it is important to ensure that your chimney meets the standards set out by relevant building regulations (Document J). These building regulations determine the size and position your chimney and flue should be so your fire can burn as efficiently as possible and you reduce the risk of fire hazards or burns.

Tests are conducted on flues and appliances to ensure they are safe and ready for use (i.e. not too big or too small and free from obstruction). The building regulations explain in detail how these tests work and why they are performed, mainly to ensure that smoke is not leaking into the house and there are no obstructions preventing a good draw. The following provides a brief summary of flue test procedures:

 Coring ball test:

A heavy ball is lowered from the top of the flue to the bottom on a rope. If an obstruction prevents the ball from moving easily down the flue, the object is removed and the test is repeated.

While this test removes obstructions, it will also determine the size of an existing flue. This can help determine which stove you should buy. A flue that is too wide can be decreased by inserting a flue liner.

Smoke test:

Building regulations stipulate that an existing chimney must be swept before a smoke test can be carried out. During the smoke test, all doors and windows in the room should be closed. The flue is heated and then pellets are lit in the stove. Once lit, the stove door is closed and smoke should be seen to leave freely from the top of the flue. The flue is then temporarily sealed at the top to ensure no harmful emissions leak into the house when smoke is held in the flue.

This test helps to establish if there are any faults in the flue and, therefore, whether or not it is safe to use the stove without causing harm to those in the house.

The relevant building regulations (Document J) can be found by contacting your local authorities or visiting the government’s planning portal website. Information on how to make sure your chimney and flue comply with these regulations can also be given by a qualified heating engineer. A reliable stove provider will be able to give you more information on how to make sure your stove is safely installed and officially approved.