Flue clearance

[ukcat]

Hi are there any rules regarding how close a chimney liner can be to the inside surface of the chimney. My chimney steps in about 200mm above the stove and the  flue spigot is almost plumb with the inside surface of the chimney where it steps in Obviously the liner can bend away but I presume it will only deviate so much over a give length. I have approx 200mm above the stove for the liner to try and clear the inside surface otherwise it will run tight against the brickwork. Just wondering how much flex the liners have