In article ,
wrote:

Running 1/4 full on full air is the way I used to do it. It means that
very little ash is left because it all burns efficiently (I only
cleaned the ash out twice from October to March in 2007 with this
method but the wood all burns away quickly and never makes it through
the night.

This might sound obvious, but have you read the manual for the stove? Ours
(a 7.5Kw and 3Kw Stovax units) explicitly says to not try to keep them
in overnight by damping them down - it then produces too much tar, soot
and other gummy stuff which will stick to the flue and be the cause of
a potential chimney fire the next time it's run really hot...

I'd also suggest that if you've managed to block the flue to get it
cleaned out now before it catches fire...

We know when ours are running efficient because they keep the glass clean.

And we mostly burn conifers too, but well seasoned wood - 18 months to
2 years, although with the recent issues with the forrestry commision
(where we have a local permit to collect), it looks like that source
will dry up soon )-:

Gordon