Sap in 4x4s

[Qvist]

I have been burning some spf 4x4s and 2x4s that are 60 yrs old. I have noticed that the 4x4s burn much longer and with more heat much more than one would expect from a 4x4 alone. (They burn longer than rounds of red maple of larger size). Has anyone ever noticed this? It seems as if they hold much more sap. Maybe this is becuase they are heartwood? It could also be tight grain structure?

 

[MissMac]

depending on how you're loading up your stove, you could be getting longer burn times because you can pack the stove so tightly and therefore have a super dense load of wood and have effectively reduced the surface area available for combustion if the load is packed flush and tight. just a thought. packing rounds into the stove = air pockets around your splits = more surface area exposed for combustion

 

[billb3]

There's no "sap" in heartwood, it's a dead part of the tree. It can also be tough as nails when it gets old and dried out.
Course there are those that profess that wood can be too old and too dry to burn so you shouldn't be having this "problem". LOL.

 

[Qvist]

It could be to dry. It is very old and dry. To the point it's almost brittle. Hard to hold back if you put to much in at once.

 

[Simonkenton]

What does "spf" mean?

 

[Sawset]

What does "spf" mean?

Genereric term for spruce pine fir?
Which one is not specified.

 

[walhondingnashua]

I would say the age and lack of surface area are your answer. One round will burn slower that if you spilt that round and burnt the two splits.
I cut and split 2 trees this summer (1 oak and the other ash) that I'm sure were dead standing with plenty of sun and wind for 20+ years, and probably more than that. They are hard as rock and near impossible to split. Its hard to get caught and produces average heat at first but it burns almost like coal. It burns down into really great coals and then burns hotter then hell and for a very long time. I throw a piece or two of it for long burns or over night.

 

[Qvist]

Yes I meant spruce pine fir. The generic term.

I would say the age and lack of surface area are your answer. One round will burn slower that if you spilt that round and burnt the two splits.
I cut and split 2 trees this summer (1 oak and the other ash) that I'm sure were dead standing with plenty of sun and wind for 20+ years, and probably more than that. They are hard as rock and near impossible to split. Its hard to get caught and produces average heat at first but it burns almost like coal. It burns down into really great coals and then burns hotter then hell and for a very long time. I throw a piece or two of it for long burns or over night.

It does burn like you say. Leaves lots of coals and they burn very hot if given enough oxygen.

 

[Kevin Weis]

See you have some old flooring in there. A lot of that was yellow pine that had pockets of resin in it. That may explain the hot fast fire if the smaller stuff.

 

[Qvist]

It may all be Southern Yellow Pine the knots drip sap as it burns. I think this is what is leading to the extremely fast burn. Once it's going it burns like oil. This could be normal not sure I burn very little SPF normally.

 

[Kevin Weis]

Yep, yellow pine with the resin (pine tar) burning. Hope your not burning the pressure treated stuff.

 

[Qvist]

This is not pressure treated. It's mostly interior walls and has no green tint at all like cca would. Also termites have eaten a good bit. I separated anything that resembled pressure treated.