I would like to install a coal/wood burning stove into an existing fireplace,would it need a liner?there is already a liner in situ installed for the gas fire that was there,would this be ok to use?
You'll need a Class 1 liner for a woodburner. Gas liners are usually Class 2. It would burn out very quickly if used with a woodburner. Also, gas uses a smaller diameter than a w/burner usually. I'm afraid you really do need to find out exactly what you have.
Naomi has prompted me to add what I should have said before .........
Solid fuel appliances must, by law, be fitted by a HETAS registered installer (including the flue) ... or by a "competent person" under Building Control supervision.