Fueling Log Burner ... The A*a* Thread

[slasherscot]

A small tip..........when the wife has let the fire go down to last few hot embers( happens every night??). pull all the embers to the front glass and  then put ur logs in....gets the fire going quicker

[openspaceman]

9 hours ago, Stubby said:

Logs radiate off each other . Its hard to get one log to burn on its own , put 3 in and away they go .  The point I was making ( very badly ) is that coal burns from the bottom up and needs air up through a gate . Wood does not .

Yes the thing is coal is mostly a solid bit of carbon, it gives off some volatiles (that's how town gas was first made) but then it just sits there glowing and not doing much. If you allow air underneath it (primary air) and a bed of hot coal to build up, the coal at the bottom produces a lot of heat and carbon dioxide, this heats up the coal above which then reduces the carbon dioxide to carbon monoxide.  So the carbon is changed from a solid to a gas. The gas then combines with air supplied from over the coals (secondary air) which produces the purple-blue flame we see when the char burns.

 

As wood pyrolyses in the fire it evolves offgas which gives 70% of the heat we feel so only 30% of the heat that comes from burning the char. Thus wood needs little primary air and that which diffuses down from the overfire air is sufficient in a little stove.

 

It is a bit more complicated than that as unlike a petrol engine, which needs almost exactly the right amount of air to fuel, with a wood fire we always supply quite a bit more air than the ideal (stoichiometric) amount and even more as the moisture content of the wood goes up. Keeping this excess air to a minimum increases stove efficiency, hence why dry wood burns better and more efficiently.

Edited January 9, 2020 by openspaceman
spelling

[Steven P]

9 hours ago, Stubby said:

Logs radiate off each other . Its hard to get one log to burn on its own , put 3 in and away they go .  The point I was making ( very badly ) is that coal burns from the bottom up and needs air up through a gate . Wood does not .

Appoligies Stubby - that's me not wording things as well as I could. You're right of course - wod needs air from above, coal needs it from below (in simple terms without going all science on the subject).

 

What I was meaning is that if you ly all the logs in one direction the top logs are blocking air getting to the lower logs, there are fewer air gaps. Lay layers at right angles and more air gaps for the air to circulate and the fire isn't stiffled by its fuel.

[Stubby]

6 minutes ago, openspaceman said:

Yes the thing is coal is mostly a solid bit of carbon, it gives off some volatiles (that's how town gas was first made) but then it just sits there glowing and not doing much. If you allow air underneath it (primary air) and a bed of hot coal to build up, the coal at the bottom produces a lot of heat and carbon dioxide, this heats up the coal above which then reduces the carbon dioxide to carbon monoxide.  So the carbon is changed from a solid to a gas. The gas then combines with air supplied from over the coals (secondary air) which produces the purple-blue flame we see when the char burns.

 

As wood pyrolyses in the fire it evolves offgas which gives 70% of the heat we feel so only 30% of the heat that comes from burning the char. Thus wood needs little primary air and that which diffuses down from the overfire air is sufficient in a little stove.

 

It is a bit more complicated than that as unlike a petrol engine, which needs almost exactly the right amount of air to fuel, with a wood fire we always supply quite a bit more air than the ideal (stoichiometric) amount and even more as the moisture content of the wood goes up. Keeping this excess air to a minimum increases stove efficiency, hence why dry wood burns better and more efficiently.

How could it be more complicated than the above ?

[Silverhooker]

Got to love stoichiometric in any sentence ❤️

[Stubby]

At the end of the day I think ( and this is my personal opinion ) a wood burning only stove is less complicated than a multi fuel stove . ?

[Peasgood]

2 hours ago, Stubby said:

At the end of the day I think ( and this is my personal opinion ) a wood burning only stove is less complicated than a multi fuel stove . ?

Beats me why anyone (especially on here) would buy anything other than wood only. Do people still burn coal/anthracite?

[openspaceman]

28 minutes ago, Peasgood said:

Beats me why anyone (especially on here) would buy anything other than wood only. Do people still burn coal/anthracite?

A mutifuel morso squirrel on my mate's narrowboat. Mostly it runs on smokeless coal as that will keep in overnight and it gets really damp and cold if it goes out.

[scbk]

19 hours ago, Peasgood said:

Beats me why anyone (especially on here) would buy anything other than wood only. Do people still burn coal/anthracite?

We use a bit of smokeless in the stove overnight, it makes a huge difference to the temperature of the house, and is a hell of a lot cheaper than electricity.

[Silverhooker]

I mix a bit of smokeless with my logs just to keep it going longer, pay about £14 for a bag delivered from my local coal man. 3 bags lasts the whole winter.