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Woodburners!
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UndercoverElephant



Joined: 10 Mar 2008
Posts: 8632
Location: south east England

PostPosted: Sat Nov 30, 2013 12:11 am    Post subject: Woodburners! Reply with quote

We are getting a woodburner-thing installed. Anybody got any particular recommendations about makes or anything else we might need to know? Going in the fireplace in the living room, which has been chimney swept. Seems to be in good condition. Sweep told us we probably don't need a liner.
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woodburner



Joined: 06 Apr 2009
Posts: 3375

PostPosted: Sat Nov 30, 2013 8:40 am    Post subject: Reply with quote

The sweep is probably right, though the installer will tell you otherwise. The liners make them more money than the stove. Steel liners have a fairly short life, but you probably won't know when they disintegrate.

Generally steel/iron box stoves are fairly poor at making use of the wood energy, though some are much worse than others. Dunsley and Clearview are two UK made stoves which are fairly good. Landy Vent UK and Cornish Masonry Stoves do some which are really good, but probably won't fit.
Inset stoves are decoration only.
Cheap stoves are inefficient fuel guzzlers,though they will still burn your fingers, physical and pecuniary in the long term.

A masonry stove is far more efficient if you have the space and money and will use small amounts of wood.



Having a flat top is very useful for cooking or a kettle (or two).

Surrounding your stove with bricks makes a better heater, though I would make a tidier job of the top, or in our case left the top exposed.

Here is a site that may give you much to think about,though I doubt you will fit one.. An example.

Wood needs to be DRY. Buying in nets now will not be ready till next year. Lighting is best done from the top, not the bottom. Look up something like upside down fires. This dramatically reduces smoke production on starting, and gives instant flames. It also means the first hour of burning will need no attention other than to shut the vent when the fire is established. If you have a glass door that gets sotted up, you aren't running it hot enough, and it indicates tar will be going up the flue. Loading it up last thing at night and closing the vents is a no-no IMO.
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biffvernon



Joined: 24 Nov 2005
Posts: 18551
Location: Lincolnshire

PostPosted: Sat Nov 30, 2013 9:57 am    Post subject: Reply with quote

I've put various woodburners in various houses and never used a liner. Against building regs but never had a problem. Yes, dry wood is important and avoid too much pine. Burn it hot at start up, then there is very little that accumulates in the flue that could catch fire.
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vtsnowedin



Joined: 07 Jan 2011
Posts: 4264
Location: New England ,Chelsea Vermont

PostPosted: Sat Nov 30, 2013 11:57 am    Post subject: Reply with quote

woodburner wrote:
Lighting is best done from the top, not the bottom. Look up something like upside down fires. This dramatically reduces smoke production on starting, and gives instant flames. It also means the first hour of burning will need no attention other than to shut the vent when the fire is established. If you have a glass door that gets sotted up, you aren't running it hot enough, and it indicates tar will be going up the flue. Loading it up last thing at night and closing the vents is a no-no IMO.

What nonsense. Heat smoke and flame rise. If you want to build a fire apply your match to the kindling placed on the bottom. And if you want heat through the night it takes a full fill up and the vents set to the idle (not closed off air tight) position.
I say this after fifty years of heating my house with wood without any other back up. Right now it is +2 deg. F outside and I have just raked over the coals from the night fire in the furnace and thrown on a couple of maple log splits. It is quite comfortable inside here at the computer table.
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woodburner



Joined: 06 Apr 2009
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PostPosted: Sat Nov 30, 2013 1:19 pm    Post subject: Reply with quote

You may be right in many other posts, but as for not lighting a fire at the bottom, you are seriously WRONG. I'll ignore anything else you write on this matter as you are lacking experience, 50 years or not. You have the internet, look up upside down fires, as I said earlier, and learn something to your advantage.

Here is just one example It doesn't apply only to outdoor fires.

Quote:
Why it works:
Heat energy actually radiates equally in all directions from the point of combustion, not just upwards (itís the displacement of gasses as they expand that sends hot air upwards, not the actual heat energy itself). So once combustion of the top layer of your upside down fire occurs, the heat energy is radiating down as much as it is up.

This in turn means that the wood below the combusting material is getting well heated before it catches fire, which in turn facilitates better and more complete combustion of the wood below when it does catch fire. And more complete combustion means less smoke.


Here's an example of lighting the "normal" way
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vtsnowedin



Joined: 07 Jan 2011
Posts: 4264
Location: New England ,Chelsea Vermont

PostPosted: Sat Nov 30, 2013 2:46 pm    Post subject: Reply with quote

woodburner wrote:
I'll ignore anything else you write on this matter as you are lacking experience, 50 years or not.

A bit rude to say the least. Fight gravity if you will. It is much more patient then I.
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woodburner



Joined: 06 Apr 2009
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PostPosted: Sat Nov 30, 2013 5:24 pm    Post subject: Reply with quote

Ok, I lied. It's not gravity that's the heat transfer mechanism, it's radiation you should look at. Do some research, you only have to click the links I gave

Quote:
What nonsense.
That's a bit rude too.
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Tarrel



Joined: 29 Nov 2011
Posts: 2447
Location: Ross-shire, Scotland

PostPosted: Sat Nov 30, 2013 6:13 pm    Post subject: Reply with quote

I guess you'll have checked if you are in a smoke-controlled area, UE? If you are, then you'll need a woodburner certified accordingly, which uses secondary or tertiary ignition to burn off the soot before it goes up the chimney.

I must confess that we throw the odd shovel of coal into the Rayburn. It creates a good hot bed on which the wood seems to burn very efficiently, with no smoke. We also keep it in overnight on coal. 2-3 kg is enough for us to have a good bed of glowing embers the following morning, with a piping hot thermal store for hot water, rads and the morning kettle.

Although our Rayburn is marketed as a specific wood-burning model, I think the core Rayburn design has coal in mind. The firebox is very small compared to even a small wood burning stove, and it can be difficult to keep the heat in there.
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vtsnowedin



Joined: 07 Jan 2011
Posts: 4264
Location: New England ,Chelsea Vermont

PostPosted: Sat Nov 30, 2013 8:09 pm    Post subject: Reply with quote

Cool The smoke goes UP the chimney! Only Santa Clause comes down it.
I'm thinking of buying the Oval model shown here,.
http://www.heartlandapp.com/products/woodburning-cookstoves/oval-woodburning-cookstove.aspx
To replace my old 100 year +/-old Andes cook stove which has seen better days. I will allow you that the smoke does go down once as it goes round the oven on its way to the stove pipe and chimney.
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UndercoverElephant



Joined: 10 Mar 2008
Posts: 8632
Location: south east England

PostPosted: Sat Nov 30, 2013 8:28 pm    Post subject: Reply with quote

Tarrel wrote:
I guess you'll have checked if you are in a smoke-controlled area, UE? If you are, then you'll need a woodburner certified accordingly, which uses secondary or tertiary ignition to burn off the soot before it goes up the chimney.


Well the sweep was local, and it was he who is going to install it, and he didn't mention anything about any of this, so I guess not.

Thanks for your replies everybody.
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woodburner



Joined: 06 Apr 2009
Posts: 3375

PostPosted: Sat Nov 30, 2013 8:57 pm    Post subject: Reply with quote

vtsnowedin wrote:
Cool The smoke goes UP the chimney! Only Santa Clause comes down it.
I'm thinking of buying the Oval model shown here,.
http://www.heartlandapp.com/products/woodburning-cookstoves/oval-woodburning-cookstove.aspx
To replace my old 100 year +/-old Andes cook stove which has seen better days. I will allow you that the smoke does go down once as it goes round the oven on its way to the stove pipe and chimney.


Look at the links I posted for upside down fires. I did not suggest you light the fire at the top of your chimney. If smoke is going up your chimney, you are throwing away fuel. Smoke will not exist if the combustion is complete. You can look at rocket mass heaters and masonry stoves for more examples of down-going flue gases (before they go up a chimney).
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Sat Nov 30, 2013 10:29 pm    Post subject: Reply with quote

UndercoverElephant wrote:
Tarrel wrote:
I guess you'll have checked if you are in a smoke-controlled area, UE? If you are, then you'll need a woodburner certified accordingly, which uses secondary or tertiary ignition to burn off the soot before it goes up the chimney.


Well the sweep was local, and it was he who is going to install it, and he didn't mention anything about any of this, so I guess not.

Thanks for your replies everybody.
Well of course I can be of no help on your local codes but when it comes to getting heat out of the available fuel I just might have "been there and done that". Nothing beats sitting beside a warm stove as a fuel truck passes by to fill up a neighbor you don't care for especially. Cool best of luck with your project.
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vtsnowedin



Joined: 07 Jan 2011
Posts: 4264
Location: New England ,Chelsea Vermont

PostPosted: Sat Nov 30, 2013 10:49 pm    Post subject: Reply with quote

woodburner wrote:
If smoke is going up your chimney, you are throwing away fuel. Smoke will not exist if the combustion is complete. You can look at rocket mass heaters and masonry stoves for more examples of down-going flue gases (before they go up a chimney).

You are playing with the definition of "smokeĒ. The completely combusted exhaust gasses from a fire whether visible or not must exit up the flue and is the "smoke" I was referring to. If you don't let them out you can't let any oxygen rich fresh air in and your fire will go out. I of course wish to extract all available heat from my fire before it exits through the chimney but pulling warm expanding gasses down against gravity and into the colder air around it is a useless trick.
If you have sufficient draft you can pull exhaust gasses through any course you chose but unless this downward course increases the heat exchange area between your exhaust gasses and the living space heat supply you are just wasting your time.
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kenneal - lagger
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Joined: 20 Sep 2006
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Location: Newbury, Berkshire

PostPosted: Sun Dec 01, 2013 4:42 am    Post subject: Reply with quote

I saw a "light the fire from the top" article somewhere and have tried it, VT, and I now use a modification of it. I make an L shaped arrangement of logs in my stove and light either a resinous piece of wood or some shavings and small pieces on top of the foot of the L. This sets fire to the top of the foot of the L and the upright at the back of the stove. Far less smoke is produced initially and the fire burns clean much quicker. Once the fire is burning well I start adding logs to the top as normal. I have been burning wood for nearly forty years and I recommend that you try it, VT, and anyone else too.

There are a number of stoves on the UK market which are started in the normal way but when the chimney is warm and an efficient draught available a damper is thrown and the draught is reversed. This has the effect of pulling all the smoke and combustion air down through the hottest part of the fire into an insulated chamber underneath the main fire where the smoke is completely burnt before going up the back or sides of the firebox, where the heat exchange into the room takes place, and into the chimney. The draw in the chimney provides the energy to drag the flue gases downwards against gravity. These stoves are highly efficient and extremely clean burning once warmed up.

Rocket stoves burn in the same way as a conventional fire but have a proportionately larger air supply and a highly insulated burn chamber so they burn the gasses completely at a higher temperature than all but the most efficient stoves. A rocket mass heater is slightly different in that the draw is provided by the cooling of the flue gasses at the heat exchange into the room. The fire burns horizontally drawn by the extreme heat generated in the vertical insulated combustion tube. The hot gasses leave the top of the combustion tube and are immediately cooled by the room heat exchanger and drop through this heat exchanger into a flue which can be horizontal and several metres/yards long and is uninsulated so that it can, and does, act as a heat source.
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Sun Dec 01, 2013 2:50 pm    Post subject: Reply with quote

Cool Variations on a theme. It is the age old problem of how to get enough surface area to draw the heat out of the exhaust gasses before they exit up the flue. The church that is in my neighborhood used to have a wood stove in each rear corner and the stove pipes ran above head high up both sides of the church to chimneys behind the pulpit some forty feet from the stoves. You would only donate the driest of maple wood to the church to keep the sooting problem down.
My main furnace is a Sam Daniels locally made in Vermont back in the 60'S. It has a fire box 24 " wide and 36" long lined with cast iron heat shields. It has two cylindrical smoke chambers mounted side by side above the firebox and the smoke rises into the back end of the right chamber moves horizontally to the front then sideways into the second chamber then back and out through a dampered eight inch stovepipe then into a forty foot masonry chimney rising up through both living floors of the house and attic to exit at the ridgeline of the roof at the point of the ell.
To build a fire in a cold start I place a piece of full sized furnace wood ,approximately 5x6x22" on each side of the firebox and place paper and kindling between them right in front of the draft door which is 7"x3" and just above the floor grate. Add some more full sized sticks on top of the kindling and side pieces then light the kindling and shut the door with the draft wide open. Pulling eight inches round worth of air through a 7"x3" opening creates a bellows effect aimed right at the kindling pile which turns into a blow torch burning between the side sticks and roasting the wood above. The furnace will actually begin to Huff, huff, huff, as wood gas begins to pour out of the logs and ignite. I check it in ten minutes and add a full load, then shut top and bottom drafts to idle and it is good for eight hours or more.
http://drc.denison.edu/bitstream/handle/2374.DEN/851/Sam%20Daniels%20Wood%20Burning%20Furnace%20Letter.pdf?sequence=1
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