Wood burning - Lime

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mike*

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Having a wood burner installed next week and have ordered a ton of kiln dried hard wood for this season.

During the recent storms a good sized lime came down on a mate's land. The tree surgeon was called and dealt with it as it was part in a neighbour's garden. All the branches and smaller stuff seem to have been removed, leaving these large rounds, up to a metre across

20231120_124732.jpg


I can have the lot if I want it! Although I appreciate I'll need to season it for a couple of years. But, a lot of online resources suggest lime is no good for firewood - burns too quickly and no heat.

I'm therefore wondering if it's worth the effort? Anyone burning lime? If no good for the stove, what else could be done with them?

Thanks for any advice

Mike
 
I wouldn't bother TBH as I've tried it with very poor results. Think hard before agreeing to take his 'waste'.

I am fortunate ...silver clouds and all that ... as we have a lot of ash dieback on our land and ash is excellent for burning.
 
It would burn, but sometimes it's more effort than it's worth.

You could probably sell it to carvers turners and buy some processed hardwood?
 
It's called basswood in the USA and often appears under that name on databases. Poor thermal output, burns fast. I have used some from branches of a tree nearby. Good for starting a fire and OK in a mix with other logs. Carvers like it because it's stable and easy to cut, pyrography is good and has good contrast. I've used some for woodturning, easy but not that rewarding, dusty to finish, very unlikely to have interesting grain.

So maybe get some of it and convert to a couple of years worth of kindling if you have room to store it. Depends what your limitations are, if you don't have much space then its not a good use of what you have.
 
It'll burn really well. Fast burning is an advantage - heats the room quicker, but you can always control it with the dampers on your wood stove.
Best reduced to firewood sized pieces now, say no bigger than 2x4x18" and stacked well to dry. Can be left stacked outside to season for a year or so and then brought undercover in summer when nice and dry.
Weight for weight it will produce the same amount of heat as any other wood - they are all made of very similar stuff, though some have more oily content.
 
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Wood has around 5.3kWh of energy per 1kg regardless of species. Typically, firewood is bought by volume, hence if you can get a cubic meter bag of Oak and Spruce for the same price you'd be better going with the Oak. If it's dried to around 20% moisture, which is the new regulations I believe, you are paying for some moisture too, so 1kg @ 20% moisture has around 4.2kWh of energy. Modern stoves that burn the gases are around 80% efficient, so you've got around 3.3kWh of energy per kg of wood @ 20% moisture.

A 'tonne'/m3 bag of firewood typically contains around 250kg of wood and water. Or, approx. 4 bags per actual 1000kg weight. Typical cost for mixed from my perusal of the internet works out around 600 quid per 1000kg. So, by my calculations you are paying around 14p per kWh of energy, or after losses on burning 18p kWh.

A lot of the sawdust briquettes like Letko get even more expensive at around 17p kWh, or 21p after system losses.

Just for comparison my natural gas is around 7p per kWh and a condensing boiler should be 90% efficient, so 8p per kWh of energy produced.

If you can 'free' wood then it works out good. It's not really free as I can attest after just felling and processing some dead trees in my neighbours garden for the last 3 hours. Otherwise, I'd just set my central heating to 18-20C and use my log burner for aesthetic purposes.

I'd also caution against turning down air inlets and letting the wood burn low as you don't get ignition of the gasses at lower temperatures so loose some energy and also produce more particulates into the atmosphere. I'd just put on less wood or change species to one that has the desired burn characteristics once you've reached optimum temperature.
 
Wood has around 5.3kWh of energy per 1kg regardless of species. Typically, firewood is bought by volume, hence if you can get a cubic meter bag of Oak and Spruce for the same price you'd be better going with the Oak. If it's dried to around 20% moisture, which is the new regulations I believe, you are paying for some moisture too, so 1kg @ 20% moisture has around 4.2kWh of energy. Modern stoves that burn the gases are around 80% efficient, so you've got around 3.3kWh of energy per kg of wood @ 20% moisture.

A 'tonne'/m3 bag of firewood typically contains around 250kg of wood and water. Or, approx. 4 bags per actual 1000kg weight. Typical cost for mixed from my perusal of the internet works out around 600 quid per 1000kg. So, by my calculations you are paying around 14p per kWh of energy, or after losses on burning 18p kWh.

A lot of the sawdust briquettes like Letko get even more expensive at around 17p kWh, or 21p after system losses.

Just for comparison my natural gas is around 7p per kWh and a condensing boiler should be 90% efficient, so 8p per kWh of energy produced.

If you can 'free' wood then it works out good. It's not really free as I can attest after just felling and processing some dead trees in my neighbours garden for the last 3 hours. Otherwise, I'd just set my central heating to 18-20C and use my log burner for aesthetic purposes.

I'd also caution against turning down air inlets and letting the wood burn low as you don't get ignition of the gasses at lower temperatures so loose some energy and also produce more particulates into the atmosphere. I'd just put on less wood or change species to one that has the desired burn characteristics once you've reached optimum temperature.
The problem with the moisture content is that there's a double whammy - not only is the 20% of the weight water and not fuel, but the energy that there is gets used to heat the water, and convert it to steam and drive it off. Even ash is around 35% when fresh cut.
A £20 moisture meter is a good investment, but take the reading from a fresh cut surface. Or keep a marked reference log and weigh it at stacking and after seasoning.
 
.....

I'd also caution against turning down air inlets and letting the wood burn low as you don't get ignition of the gasses at lower temperatures so loose some energy and also produce more particulates into the atmosphere. I'd just put on less wood or change species to one that has the desired burn characteristics once you've reached optimum temperature.
Definitely. A small fire burning small dry stuff fast and hot is much more efficient, but needs stoking more often. It's the rocket stove idea and works similarly in bigger stoves. If i want to heat the room quickly then sawdust and planer shavings are best.
It's also better for the flu - we just had ours cleaned by a professional first time for 10 years and he gave it top marks!
 
Thank you everyone for the comments and opinions. As ever the members here prove themselves to be knowledgeable, practically and theoretically.

I think what I'll do is take a couple of the rounds and chop them up for kindling, and then chop another couple for larger pieces, just for the sake of experience. My only expense will be time and effort. I'll let you know how they burn in a couple of years time!
 
At the risk of derailing my own post...

I have an 8lb maul. Never used one before. No access to powered tools - what would be your approach to chopping these rounds to size? I'm kind of assuming the first thing to do is get then halved and then quartered?

I did swing the maul into one of the rounds, and it didn't really do much damage. In fact, on a couple of occasions it kind of bounced. I understand a maul doesn't need to be as sharp as an axe, but I'm assuming some kind of apex edge is necessary? Maybe the wood is still too wet? The tree only came down a month or so ago, and has also been out in the constant recent downpours. When the maul does penetrate I can visually see water oozing out, like a squeezed cloth. Should I leave it a bit longer before chopping?

Any other tips? Feel stupid asking, as on the face of it, it seems an easy task (excepting the physical element and time...), but in 57 yrs I've never logged wood.
 
Lime is wet...and cut rings in the rain get even wetter. Turn them on edge and cover for a couple of months; then try again. It should split nicely, even though the wood isn't great for burning too light so takes a lot of space, and burns rather cold)
 
At the risk of derailing my own post...

I have an 8lb maul. Never used one before. No access to powered tools - what would be your approach to chopping these rounds to size? I'm kind of assuming the first thing to do is get then halved and then quartered?

I did swing the maul into one of the rounds, and it didn't really do much damage. In fact, on a couple of occasions it kind of bounced. I understand a maul doesn't need to be as sharp as an axe, but I'm assuming some kind of apex edge is necessary? Maybe the wood is still too wet? The tree only came down a month or so ago, and has also been out in the constant recent downpours. When the maul does penetrate I can visually see water oozing out, like a squeezed cloth. Should I leave it a bit longer before chopping?

Any other tips? Feel stupid asking, as on the face of it, it seems an easy task (excepting the physical element and time...), but in 57 yrs I've never logged wood.
Get 3 wedges and use them, lime can be tough to split.
 

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