For a stove to work well you require at least 12 Pa (Pascal’s) of pressure to ensure it draws properly. A good installer will check this for you and right this on your installation certificate, and in some cases the manufacturers operation manual.

If your flue is not achieving this there are a number of reasons, but the main three can be that the flue is not high enough, or it isn’t insulated, or it is incorrectly designed with too many bends or whatever.

To insure that a chimney that is lined also draws properly, is another reason that a good installer will insulate around the liner.

When installing a stove doing a hot flue spillage test is also a good idea to ascertain the efficiency of the flue design.

If you are designing a flue for a passive house with a positive pressure heat recovery system,  then you need a passive flue to minimise the air loss.

These are all thing that a good installer can advise you on and will incorporate in the flue design.