The usual rule for any chimney lining or alteration which has been made to run a gas fire is "All Out". The gas liner is not made from a metal strong enough to cope with the heat from the stove and will start to disintegrate releasing noxious fumes. You will need to replace this gas liner with a liner suitable for a stove if your chimney is leaking. It may be that you will find your brick chimney is in good order, however if your chimney leaks we can supply a full lining kit.
The same "All Out" rule applies to metal chimney flues and liners which have been installed for oil burners.
If you would like more details or assistance with the installation of a Country Kiln Wood Burning Stoves please email your query to firstname.lastname@example.org (The Country Kiln team respond to all emails within 24 hours) or call 01560 483966 Monday to Friday 9am to 5pm GMT or Saturday 10am to 1pm