It could be that there is a confusion between Elder and Alder, totally
different trees. Elder (usually only a small bush, biggest logs
you'll get are only three or four inches diameter) really doesn't burn
It needs a good hot fire to burn well but that's all.
On 15 Aug 2006 08:02:36 GMT, email@example.com wrote:
Yes, that sounds likely. Similarly, but not a problem in the UK, we have
locust bean trees on our farmland. The logs from that won't burn at all,
even if baked in the sun until they are bone dry. All they do is smoulder
It's also bollocks..to generate any sort of heat is about a cubic meter
of ash a month, in my experience.
Not a lot wrong with that - we use a couple of open fires and a
'highwayman' stove here..only one open fire is used consistently though.
The highwayman is definitely less draught inducing and more efficient
than the open fire..we have it in our bedroom for days when we have the
A good wood burner kicks out an easy kilowatt, and can be persuaded up
to about 2-3. Our huge open fire is about 10KW, but a lot goes up the
chimney..it takes ages to warm the room as mostly the first three hours
its warming the brickwork around it. However it keeps the room hot all
night afterwards. We tend to light it about 2pm in the winter, so that
by 5pm its really well set up. It dies around 11pm which is a couple of
hours before we hit the sack.
There is something seriously flawed with your stove or more likely
the way you use it.
Mine has a plastic shopping bag full of ash which will have become
almost rigid and that is about once a month with a fire on day and
Perhaps you are burning fresh timber or more likely you have a grate.
Its best to burn the fire on the floor of the stove with no grate. That
way you always have a hot bed of ash under it.
you use the traditional fireplace for your living room so perhaps you
should not talk so knowledgably about wood burning stoves when you
clearly have limited experience of them.
That scenario would be much improved if you installed a wood burning
stove in your living room. You could get 10 kw and lose very little up
the chimney if you did what I said earlier.
You would probably burn much less timber in the stove and get far
better heat output and therefore put less of those pollutants you refer
to into the atmosphere.
You dont know what you are missing.
Our good woodburner kicks out about 8KW according to the specs. It's
Stovax unit, and although it's relatively new to us (and therefore we
haven't use it that much - it's still summertime in Devon ;-) when we
have run it up, we've been more than impressed with it.
Dunno. But fan blown furnaces fed on sawdust and chippings are supposed
to be ultra low pollution.
The more oxcygen you get in the less carbon monoxide, and the higher the
combustion temp, and the greater chance of breaking all organics down
into simple stuff like H20, CO2 and SOx. And possibly NOx. AFAICR thats
pretty much what wood is made from by and large..the trace stuff tends
to stay in the ash.
No, generally NOx level rise as combustion temperature rises and free
oxygen in the flame increases. This is why diesels have exhaust gas
recirculation - to reduce the amount of available oxygen when there
isn't a full fuel charge.
Pay no attention to that man behind the curtain.
Yes broadly I think so but generally you need to limit excess air as
this cools combustion. The thing is the dryer the wood the less excess
air needed for a good burn.
True but you're talking about a fuel with a much higher cv and flame
temperature. Generally wood burners don't get to the high temperatures
where NOx would be formed in any quantities because of the lower
calorific value and the latent heat of steam from moisture in the
wood. Oven dry wood may be a different matter but even then we're only
talking about maximum temperatures of 1600C.
The pellet stoves often have closed loop and the higher tech
(industrial looking) boilers for both woodchip and logs do but the
cost is quite high. I saw a recent quote for a logwood installation,
with closed loop, that was GBP11k compared with a similar spec oil
install, with tank, of GBP4.5k.
Having said that it's fairly straight forward to build a small, blown,
stove that has CO<100ppm, I've not been able to measure much else,
with no feedback and simple air control for limited modulation. The
crux is not attempting to burn wet wood.
The old National Coal Board licensed their design for a understoked,
anthracite bean, domestic boiler to two companies. I have seen the
poorly made model but not the better made one, I doubt they remain in
production. I think these would burn woodchip with a bit of
IMO forced air is the single most effective way to clean up woodburner
emissions. BTW if you can see *any* smoke you must have fairly high,
say 500+ ppm, CO.
> Given all this is there no stove maker that has a design with
Yes it is a sweet dream but dont believe them.
It all depends on how much wood you burn, how big the logs are, how you
control the doors or air intake and the quality of the timber you burn.
Not to mention the size of room, the temperature, the wind chill and
how cold a person your wife is and many other variable factors.
There is no pie in the sky answer.
Some people never get warm.
This may all be true but the job I am looking for is, I would hope,
the advantageous and efficient wood burn and minimisation of
emissions. I do not think we should be sidetracked by expecting a
heating system to address the other aspects you mention as they would
affect ANY heating system. The optimal combustion can be addressed
I am starting to wonder that if this product does not exist then I
should seriously look into its development as a product since I have
a background in analogue sensing, DSP and manufacturing design.
However, with the development that companies like Tarm
(www.woodboilers.com) have carried out then there is likely another
manufacturer that has addressed, or is developing room stove designs.
Thanks again AJH.
I found this from a mail list on the subject of gasification. I now
need to explore the particular difficulties Gavin (the author)
presented with small scale designs. I may be able to contribute to the
control loop, if this is indeed the obstacle in small-scale designs
=========Small wood burners do not run as cleanly and efficiently as gasifiers
because to control gasification you need controlled air supplies and
consequently some sort of feedback . Gasification boilers like
Kuenzel, tarm and Kob are much more expensive than a "conventional"
boiler because of this control and feedback loop however they can
achieve much higher efficiencies and clean combustion
One place I would see potential to develop further in a wood burner is
by utilising the waste heat going up the flue so that it heats a water
jacket which need not be attached to the stove.
that would take some of the heat going to waste and if a round or even
a square jacket of water say about one yard long was inserted just up
the chimney I think it would produce a good supply of hot water from
heat that would otherwise just go up the chimney.
I am averse to putting a water jacket in the stove as you neither have
a fire nor hot water unless you really put on a good fire.
What do you think of this idea Tim?
Cue condensation of the tars and acids, a chimney fire and a rusted-out
Take heat out of the firebox if you want, where it's big and there's
plenty of airflow. But leave the flue gas alone, lest you annoy it.
Although we'd love to have the flue gas leave the terminal at a nice
efficicent barely-above-room-temperature, it just isn't practical to do
this on a workable system. You need to keep that gas hot, and you need
to keep it moving.
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