biffvernon wrote:But there's not much difference in calorific values between different species of wood, measured by mass at the same moisture content.
Precisely.
Not a lot of people realise that ash and, say, willow have more or less the same calorific value by mass. The reason they don't have the same calorific value by volume is because willow is less dense. This poorer calorific value by volume is further exacerbated by willow's greater absorbency of water, possibly linked to it's lower mass by volume.
Thus if one has a ton of totally dry willow and a ton of totally dry ash, they will both produce more or less the same amount of heat in the same amount of time. The willow just needs to be fed into the fire more regularly than would be the case with ash.
biffvernon wrote:But there's not much difference in calorific values between different species of wood, measured by mass at the same moisture content.
True, but above we were talking cubic yards/metres/feet, and because the densities vary there can be a significant difference in heating value buying by volume -- buying wood by the cubic-anything can leave you a bit short! Which practically is why (perhaps excepting the gentrified weekenders doing a bunk from London or Birmingham who get their "sacks" at the garage) I and everyone I know around here buys wood by the tonne.
Most people sell wood by the "load", which is whatever fits on the back of their tipping van, or by the "dumpy bag" which they claim is aither 1 cubic metre, 1 yard or 1 ton. In fact it's often closer to 0.6 ton.
"Heavy" wood obviously burns for a long time. Oak and Hornbeam are my favourites, useful to keep the stove burning overnight. Ash is a great wood, and if you leave some unsplit, in the round, it can also burn slowly to keep in overnight. Sweet chestnut spits like crazy, but is actually pretty good in a stove, I burned loads of it, it makes great kindling.
Neighbours in London have recently had a woodburner installed, to directly heat the room in which it is situated, and also provide gravity circulation to small radiators upstairs.
They have found that affordable firewood in London is scarce, and that the main source is demolition contractors who now sell the wood from buildings that they knock down, rather than burning it on site.
They recently bought 7 tons of logs for £140, but freshly felled so no good for burning for least two years, and they wont weigh 7 tons when dry !.
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
adam2 wrote:They recently bought 7 tons of logs for £140, but freshly felled so no good for burning for least two years, and they wont weigh 7 tons when dry !.
Still sounds cheap (though what's the wood?), especially for London.
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
Took the Eucalyptus down - took 2.5 hours start to finish. Started by taking all the limbs off and then took the trunk down in 2 metre lengths. Easy to manage doing it this way. The last cut working almost at ground level was a nightmare. Had to use a wedge and sledge to finish it off. Only used Bow saws - don't like the chainsaws for health reasons.
I would say Eucalyptus is a medium density wood - gave off a lovely smell. Should be good to burn for next winter. Certainly won't have to wait 2 years (Adam). Completely filled my trailer so happy enough and probably burnt off 1000 calories doing the job. Ruined by buying myself and acomplice Kentuky Chicken Burger meals on the way home - haven't eaten those for donkeys - tasty when you are famished!
adam2 wrote:They recently bought 7 tons of logs for £140, but freshly felled so no good for burning for least two years, and they wont weigh 7 tons when dry !.
Still sounds cheap (though what's the wood?), especially for London.
Not certain, very mixed. Obtained from someone whom cuts back and fells trees for a living.
"Installers and owners of emergency diesels must assume that they will have to run for a week or more"
Thanks Lurker - that is incredibly fast growth. Not quite so quick up here, but the wood should be fine for burning by next year. Mostly now cut-up and thicker logs split - wet wood alright.....
Got a very nice load of wood today, 2/3 of a trailer of 2 year seasoned oak - burnt sonme of it tonight! And a further third oif evergreen - wil take 3-4 months to dry.
So, now have 4 out of 5 wood stackers well and truly full. Should do me the winter and still some more stacking to come.
I reckon we are in for a cold one. Son reported snow lying in Aberdeen last night and this morning. We had a frost here this morning and ice still lying in puddles at lunchtime!
I assumed there was a mix up between feet and yards.
Yeah it was a mix up im usless using imperial units
Still with volumes 1 cubic yard is quite alot less than cubic meter .
1 yard = 0.9144 meter
1 cubic yard = 0.836 cubic meter
So about 20% smaller
30/0.836 =
Works out at £35.89 per cubic metre still avery cheap price! Worth getting i reckon if you have the money space etc.
Is it loose packed in crates or tightly stacked makes huge difference
One loose cubic metre = 0.62 stacked cubic metre = 0.4 cubic metres of solid timber. This from a Finnish guy on Arbtalk. Apparently the business of selling firewood is very stractured and organised there. It's always sold by volume, not by weight.
Selling by weight makes sense, as it is directly related to calorific value. Trouble is, it's not very practical, especially for small producers, requiring weighbridge facilities or similar.
There's a guy near me sells firewood by the kWh, and prices it competitively with other ways of gaining those kWh, such as gas, oil or electricity.
Got another trailer full of wood on the Sunday and it is waiting to be cut up this weekend when I have light. Hope to get one more trailer this coming weekend too. The wood is disappearing, so there is somebody else helping themselves....
. Mature Sweet Chestnut coppice will grow like that, but it has a 100+ year old root system to fuel it.