In message o.uk, Dave
Liquorice writes
On Sun, 13 Jan 2013 18:43:33 +0000, Dom Ostrowski wrote:

That sounds a rather fast soot build-up to me.

It's not soot, at least not soot as in fine powdery possibly slightly
oily stuff that I remember as soot from the open coal fire when I was a
lad. This is hard brittle black lumps and some very light and crispy
browner bits.

When I was heating this place by woodburner alone (Jotul, similar size,
similar fuel, similar rate of consumption, no backboiler) I swept it
myself twice a year and got out out half a bucket of soot from the
flue, and only light sweepings from within the stove itself.

I think the boiler makes a heck of difference to flue gas temperature,
thus flue temperature and how much tar will condense out. When it was
swept back in Oct I didn't think that much came down, it certainly didn't
sound like much came rattling down. But as I didn't do it I don't really
know.

It appears to be a little *underaired* as you sound to be gasifying the
wood. I'm no expert though. AJH might have some better knowledge. Our
Clearview gets through a heaped garden barrow of dry logs in a full day.
I haven't yet fitted a boiler or swept the flue:-(

There is lots of stuff on the manufacturers sites about combustion. ISTR
the Clearview one warns about boilers dramatically reducing the
combustion temperature and leading to sooty windows.

Do you run the fire closed down overnight? This quickly blackens the
glass on ours.


--
Tim Lamb