On Sun, 25 Feb 2018 21:14:05 GMT, house13
m wrote:

We installed a wood burner about 6 months ago before installing it the chimney
was swept and it worked well.
We are unable to use it now as it gives off a very toxic smell, we have had it
cleaned and the chimney swept again, but the smell is still there.

What did the Chimney Sweep suggest?

We don't know the wood being burnt.