"Upside-down" fire: gasifier

To what extent will biofuels be part of our energy future?

Moderator: Peak Moderation

User avatar
RenewableCandy
Posts: 12777
Joined: 12 Sep 2007, 12:13
Location: York

"Upside-down" fire: gasifier

Post by RenewableCandy »

What do The Panel reckon to this?
The method is simplicity itself: do exactly the opposite of the tipi method.

1) Put the largest logs at the bottom, ensuring there is no space at all between them.

2) Put a second layer of smaller logs on top of the largest, again ensuring there are no spaces between them.

3) Repeat until you get to the top, where you will have strips of crumpled paper and — at the very top — 3-5
...and I'm not sure what those things are or what they're made of.

I've not tried it because we don't have an open fireplace, but perhaps someone could report back?
Soyez réaliste. Demandez l'impossible.
Stories
The Price of Time
User avatar
RenewableCandy
Posts: 12777
Joined: 12 Sep 2007, 12:13
Location: York

Post by RenewableCandy »

And there's more!

Home-made little gasifier
Soyez réaliste. Demandez l'impossible.
Stories
The Price of Time
User avatar
emordnilap
Posts: 14815
Joined: 05 Sep 2007, 16:36
Location: here

Re: "Upside-down" fire: gasifier

Post by emordnilap »

RenewableCandy wrote:What do The Panel reckon to this?
The method is simplicity itself: do exactly the opposite of the tipi method.

1) Put the largest logs at the bottom, ensuring there is no space at all between them.

2) Put a second layer of smaller logs on top of the largest, again ensuring there are no spaces between them.

3) Repeat until you get to the top, where you will have strips of crumpled paper and — at the very top — 3-5
...and I'm not sure what those things are or what they're made of.
Neither am I but, if they're similar to Zip firelighters, they involve fossil fuels which are not particularly pleasant at all. These are a preferable alternative if you must use firelighters. They shouldn't really be necessary.

He mentions that there's little ash at the end of burning; this could be very efficient burning or some goes up the chimney due to the fireplace design. Our woodstove only gets emptied of ash every couple of weeks, and I can tell very little ash gets taken up the chimney.
I experience pleasure and pains, and pursue goals in service of them, so I cannot reasonably deny the right of other sentient agents to do the same - Steven Pinker
woodburner
Posts: 4124
Joined: 06 Apr 2009, 22:45

Re: "Upside-down" fire: gasifier

Post by woodburner »

RenewableCandy wrote:What do The Panel reckon to this?
The method is simplicity itself: do exactly the opposite of the tipi method.

1) Put the largest logs at the bottom, ensuring there is no space at all between them.

2) Put a second layer of smaller logs on top of the largest, again ensuring there are no spaces between them.

3) Repeat until you get to the top, where you will have strips of crumpled paper and — at the very top — 3-5
...and I'm not sure what those things are or what they're made of.

I've not tried it because we don't have an open fireplace, but perhaps someone could report back?
You don't need an open fireplace, it works in a wood burning stove too. I've been lighting my fires upside down for years. Much less smoke at startup.
To become an extremist, hang around with people you agree with. Cass Sunstein
User avatar
adam2
Site Admin
Posts: 10882
Joined: 02 Jul 2007, 17:49
Location: North Somerset, twinned with Atlantis

Post by adam2 »

Ideally, when burning wood or coal, the fresh fuel should be placed UNDERNEATH the already burning fuel, in order that that smoke and gases from the not yet properly burning fuel are passed through the hottest part of the fire and fully burnt.
This is of course not practical with any standard type of stove or fireplace, the Victorians knew this and designed various complex contraptions that claimed to insert the fresh fuel under the already burning fire and thereby "ensure perfect combustion and the absence of smoke" Such devices worked to an extent under ideal conditions but never found much favour due to the mechanical complications.

When initialy lighting the fire in a stove there is much to be said for covering the grate in fuel, and lighting the fire from the top as described above. This gives better and cleaner combustion and also extends the time until the first refueling.
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
User avatar
Catweazle
Posts: 3388
Joined: 17 Feb 2008, 12:04
Location: Petite Bourgeois, over the hills

Post by Catweazle »

Clean burning wood stoves like the Dunsley Yorkshire are DEFRA approved for use in smoke control areas through the use of down-burning. A bed of hot coals forms at the bottom rear of the firebox where the flue is, smoke from newly added wood is drawn through this bed of coals where it is heated, then a secondary air intake at the back of the stove allows a second combustion of this smokey mix. Once the stove is up to temperature there is no visible smoke at all. I had the boiler model, the water jackets surrounded the secondary combustion chamber very well and it was efficient.

The only downside was that it was a little more difficult to light than a conventional stove, because you have to start the fire at the bottom rear in order to get a draught going in the chimney but once it was lit I could put any sized log on it without problems.
Tarrel
Posts: 2466
Joined: 29 Nov 2011, 22:32
Location: Ross-shire, Scotland
Contact:

Post by Tarrel »

I'm going to be lighting the Rayburn in about an hour. I'll try it.

Had our first chimney fire yesterday! :roll:

All safe and well. No damage. :)

Had a room full of firemen though. Made a change for a Sunday afternoon :shock:
Engage in geo-engineering. Plant a tree today.
woodburner
Posts: 4124
Joined: 06 Apr 2009, 22:45

Post by woodburner »

Tarrel wrote:Had our first chimney fire yesterday! :roll:

Burning wood too slowly
To become an extremist, hang around with people you agree with. Cass Sunstein
Tarrel
Posts: 2466
Joined: 29 Nov 2011, 22:32
Location: Ross-shire, Scotland
Contact:

Post by Tarrel »

woodburner wrote:
Tarrel wrote:Had our first chimney fire yesterday! :roll:

Burning wood too slowly
Yes, and it's not properly seasoned. Will be better next winter. Also, we bank the Rayburn down overnight, which probably doesn't help.

To be honest, the chimney is a bit overdue for sweeping. With a Rayburn they recommend around 3 times a year. We're shutting ours down for the summer in a week or so. We'll have it done then, ready for a September re-light, and then again after Christmas.
Engage in geo-engineering. Plant a tree today.
woodburner
Posts: 4124
Joined: 06 Apr 2009, 22:45

Post by woodburner »

If you are running on wood, it will be impossible to make the Rayburn run for more than a few hours without adding more fuel. Treat chimney fires as dangerous. They often do for houses if they start at the wrong time.

Using http://www.chimneycowlproductsdirect.co ... eaning_log can help. You can find them a bit cheaper, but compared to the cost of the loss of house, £2 isn't worth worrying about.
To become an extremist, hang around with people you agree with. Cass Sunstein
vtsnowedin
Posts: 6595
Joined: 07 Jan 2011, 22:14
Location: New England ,Chelsea Vermont

Post by vtsnowedin »

8) Smoke up the chimney is not an issue with me as I'm out in the country. For efficient and long burning fires in the furnace I take advantage of the three foot depth of the fire box by pushing the burning wood and coals to the rear where there are no draft holes from below before recharging the front with close stacked wood over the grates with few if any coals under it. This forces the fire to back burn against the draft to start the new wood and the wood gas and smoke from the new wood passes over and through the coals and fire between it and the exit flue. This yields a lull in the heat output followed by a charge of heat in the middle of the night while we are sleeping and the outside temp is dropping to it's morning low. Low tech but it works.
This is a old locally built wood furnace that has a 47"x47" footprint in the basement and an 8" flue. It has twin smoke chambers above the fire box and cold air returns enter the sheet metal sides by gravity and move to the inside up the fire box and around the smoke chamber then out through a center top duct and on to the upstairs living area.
http://drc.denison.edu/bitstream/handle ... sequence=1
User avatar
RenewableCandy
Posts: 12777
Joined: 12 Sep 2007, 12:13
Location: York

Post by RenewableCandy »

We have a stove that works along similar principles to the Yorkshire, and yes there's no visible smoke once it gets going. But there's some at startup, so I'm tempted to give the upside-down method a go now that a quick fire-up isn't quite so urgent (i.e. it's not February, unlike last week!).
Soyez réaliste. Demandez l'impossible.
Stories
The Price of Time
Tarrel
Posts: 2466
Joined: 29 Nov 2011, 22:32
Location: Ross-shire, Scotland
Contact:

Post by Tarrel »

Tried it with the Rayburn. Didn't work. All the small stuff on the top burnt away, then it went out. Maybe pilot-error?
Engage in geo-engineering. Plant a tree today.
User avatar
RenewableCandy
Posts: 12777
Joined: 12 Sep 2007, 12:13
Location: York

Post by RenewableCandy »

I keep thinking that's what would happen with our stove, too. Perhaps it's because the stove itself already directs the smoke through the fire (a la Dunsley Yorkshire above).
Soyez réaliste. Demandez l'impossible.
Stories
The Price of Time
User avatar
mikepepler
Site Admin
Posts: 3096
Joined: 24 Nov 2005, 11:09
Location: Rye, UK
Contact:

Post by mikepepler »

Tarrel wrote:
woodburner wrote:
Tarrel wrote:Had our first chimney fire yesterday! :roll:
Burning wood too slowly
Yes, and it's not properly seasoned. Will be better next winter. Also, we bank the Rayburn down overnight, which probably doesn't help.

To be honest, the chimney is a bit overdue for sweeping. With a Rayburn they recommend around 3 times a year. We're shutting ours down for the summer in a week or so. We'll have it done then, ready for a September re-light, and then again after Christmas.
We bought a professional sweeping set for about £120 (from http://www.thewakefieldbrush.com ), and do our stove every 6 weeks or so over the winter, then pay a sweep to come once a year so we get the certificate. It's having boilers in the stove that does it - it burns much cooler, so you get more soot - after 6 weeks, there's a good pile in there, even burning 2-year old wood!
Post Reply