Sitka spruce

[Whistling Kettle]

13 minutes ago, Muddy42 said:

 

Sitka is great firewood.  I've occasionally had a half lorry load from nearby forestry when they don't want to transport it across the country.  Then its been all ive burned for months.  You should be able to burn that wood in the winter of 2026, if its brought under cover with good airflow, during a dry spell next summer.

The wood in the pic is mainly Ash with a small amount of Oak and Beech,  just take small amounts at a time that I can fit in the motor from jobs I do

The plot I'm in is mainly spruce, but very heavy in Birch aswell

[Whistling Kettle]

Blowing like a steam train without the spark arrestor 

[openspaceman]

Just goes to show what burning wet wood can do.

[Rob_the_Sparky]

Back to the original question:

 

At home you can burn all woods without problem as long as the fire is kept hot.  The problems occur when the fire is hot enough to turn the oils/tars in the wood into gas but not hot enough to ignite them.  When that happens, as the gasses cool in the chimney these oils and tars condense on the inside of the chimney.  Generally, as softwood has a higher proportion of tars/oils in them than hardwood you can get the problems you are seeing in your tent stove.  The same thing can happen at home if the fire is not kept hot enough.  It is not unique to softwood but it will happen faster as there is more tar/oil in it.

 

This is not a good thing due to the blocking of the chimney but also as you are storing fuel in the chimney.  If the chimney gets hot enough at a later date it can ignite this stored fuel and het presto you have a chimney fire.   No fuel = no chimney fires.

 

From an energy point of view, per unit mass of dry wood there is very little difference between types of wood.  Hence, softwood makes a good firewood if handled right.  Generally it is less dense so you need more of it in terms of volume and it can burn faster so better to leave it in larger chunks than hardwood.  On the plus side it is cheaper as many people do not understand the above and it generally dries faster than a more dense wood.

Edited 5 hours ago by Rob_the_Sparky

[Rob_the_Sparky]

N.B. as you have to evaporate a lot more water with a wet wood you will struggle to maintain a high fire temperature.

[Muddy42]

3 hours ago, Rob_the_Sparky said:

Back to the original question:

 

At home you can burn all woods without problem as long as the fire is kept hot.  The problems occur when the fire is hot enough to turn the oils/tars in the wood into gas but not hot enough to ignite them.  When that happens, as the gasses cool in the chimney these oils and tars condense on the inside of the chimney.  Generally, as softwood has a higher proportion of tars/oils in them than hardwood you can get the problems you are seeing in your tent stove.  The same thing can happen at home if the fire is not kept hot enough.  It is not unique to softwood but it will happen faster as there is more tar/oil in it.

 

This is not a good thing due to the blocking of the chimney but also as you are storing fuel in the chimney.  If the chimney gets hot enough at a later date it can ignite this stored fuel and het presto you have a chimney fire.   No fuel = no chimney fires.

 

From an energy point of view, per unit mass of dry wood there is very little difference between types of wood.  Hence, softwood makes a good firewood if handled right.  Generally it is less dense so you need more of it in terms of volume and it can burn faster so better to leave it in larger chunks than hardwood.  On the plus side it is cheaper as many people do not understand the above and it generally dries faster than a more dense wood.

 

Hot fire or not, every stove manual ever written will tell you not to burn wet wood. A neighbour of mine managed to totally block his new cowl and flue in one season, requiring replacement at some cost.  Chimney fires can destroy your flue liner, chimney pot etc or even worse case burn your house down.  Its simply not worth gambling here!