I have only been using my woodburner for 3 months and suddenly there is tar, or something running down between the joints in the flue pipe!! Can anyone help?

the joints in the chimney are not tight enough.
my friend has just had an essy fitted and the same thing happened to him as the tar is a residue that builds up off the type of wood that you are burning and as it heats up the flue it melts it and makes it into more of a liquid form.

If you go and speak to Jorge at Pavesequa, the builders merchant in Porta Nova opposite the small round about/T junction. He will sell you a tube of high temperature silicon sealer especially for flue pipes. If you re-seal the tubes with this it should solve your problem.

I had the same problem because the flue had been put together with the old fashioned type clay sealer.

Thanks I will give it a go!