All woods have a similar energy to mass ratio at the same moisture content , about 4kWh/kg for air dry hardwoods, a fraction more for softwoods.
The thing is air dry softwoods, poplar and willow have a low density so you have to store a higher volume and stuff the firebox more frequently
Now if you are growing to burn, commercially, the swamp trees are excellent as they add the most (dry) biomass per acre per year.
But the wood needs a lot of drying out - I think that's what Drax burns
- and they have it pelleted.
yes, but the problem with willow and so on is they never seem to dry out completely, I've tried to burn a lot of poplar - aspen - and it never seems to want to burn easily, it just chars. It does get there in the end, but it simply isn't a patch on things like maple or ash
that is certainly true.
Arsenic is a tonic (in very small quantities) Probably apocryphal but my father used to say that horse dealers would feed some to animals for sale to make their coats shine.
I wonder how much is volatilised in the fire and how much stays in the ash? There is a definite metallic tang in the back of the nose if you smell the smoke of CCA treated wood.
The chrome is quite nasty as it changes valency when burned to the hexavalent form which is a carcinogen.
Safest thing with CCA treated posts is to land fill them I guess.
Our local common used CCA posts, before the ban, to fence grazing animals in, despite my pleading to use chestnut as I was aware of the problem. They mostly broke over twenty years and when replaced have been discarded at the side of the fence. I notice them disappearing as people take them home
There used to be an old WW2 radio tower not that far from here on Detling Hill. I believe it had been part of the GEE network although I never verified this. For many years it was used for PMR etc, then it was used only for the local amateur repeater, until the site owner was required to take it down. I climbed it many times to work on the repeater antenna- it was made of wood, perhaps 4x4 or so, treated with some tar like substance.
The local amateur who, for many years had acted as the Repeater Keeper and, in effect, paid the rent for the use of the tower space by acting as a caretaker of the site- keeping the grounds clear weeds, being a key holder etc. was able to obtain some, possibly all, of the scrap wood.
He had a wonderful, open, fire in his house and it kept him in firewood for ages.
Someone has been carting off my pre-war fencing rails. Creosote/tar impregnated Cedar? Good for fire lighting perhaps.
The posts have long gone so maybe they just like a tidy countryside.
Probably good old fashioned coal tar creosote, it was found to be carcinogenic so use became deprecated. It also became expensive to use in a full vacuum-pressure cycle because so much active ingredient went in the wood.
CCA didn't really seem to take off till the 60s and the active ingredient was something like 5kg per m3 of wood but it was absorbed differentially between species and moisture content. The plants I supplied post blanks to were blithely unconcerned about this and all the wood was loaded in and put through the same cycle almost fresh from harvesting. This resulted in most of the active ingredient dripping off immediately the pressure vessel was drained.
Well, I'm not as old as you, but given the symptoms:
- They were wet on the outside when he got them
- They sat outside till they were superficially dry
- They still wouldn't burn
- he didn't buy them from a reputable supplier
What do you think are the chances that they weren't wet all the way through? Green wood, recently cut, and not seasoned?
Andy
A couple of weeks back I read an old book I'd been given "Tales of the old country vets" and one mentions this practice.
Andy
yep.
green wood is a bitch to burn, but dry wood that has been rained on dries very rapidly. Consider the volume of water in a 15% RH log compared with the volume of water on its surface.
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