Apparently logs can be too dry

[neiln]

Yes I know, my stovax has primary, airwash and then what it calls secondary, the heated air that enters the top of the fire box and should ignite the smoke. US stoves meeting current EPA regs can be tube/air feed secondary but a good proportion use a catalytic matrix. Just like the cat in a car exhaust, it triggers the burn of the polutants at a low temp. I think the big advantage those stoves have is very long burn times, as the primary air can be turned right down, giving a slumber, yet the cat ensures a clean burn.

 

Just to add, the tertiary air on my stove ( secondary as stovax call it) is adjustable although I've worked out in never shuts completely. The Defra smoke control kit though, consists of an alternative air wash lever, which ensures the airwash is always part open and the user can't slumber the stove. I'm slightly surprised the smoke control kit doesnt instead ensure the secondary air remains open further.

[Woodworks]

25% is just not good enough IMHO yet according to Hetas its fine !!.

Logs at 15% would generate about 40% more heat, have a look here:

 

http://www.forestry.gov.uk/pdf/eng-woodfuel-woodasfuelguide.pdf/$FILE/eng-woodfuel-woodasfuelguide.pdf

 

If you cant naturally get the internal MC down that far then KD is the way to go, either yourself maybe with RHI or buying in ready KD logs from the Baltic. Under an open dutch barn in vented bags I can get air dried logs down to about 10% external in September having processed in April. Cord is usually a couple of years felled. I am in the midlands so have no sea fogs which I assume is an issue for you. Bear in mind that wood is hydroscopic so will draw moisture in from the atmosphere once out of the kiln.

 

I have a customer driving 40 miles every week to buy 10 packs of my kiln dried Birch in small nets as he has no storage space for a large crate, in an Audi A5 !!. Another does a longer run in a Porsch 4x4.

 

A

 

From the table you posted logs at 25% V ones at 15% is a drop of 14% not 40%. I was being a bit pessimistic saying ours are at 25% as in reality on inspection most are at 20% ish but 15% is unachievable at this time of year unless we get a prolonged easterly which is very rare. Fog is our problem but the hill variety. But fog or no fog external RH is normally in the nineties. In the very dry late Autumn the best ours got down to was 17%. You are very lucky having a climate where you can air dry down to 10%. Guess you must be effected by the Foehn effect?

 

We could buy in kiln dried logs but whats the point? We don't have a shed that could be humidity controlled and I don't have a single customer who stores there logs in their house or humidity control shed. All that extra drying would be completely wasted and logs would go back up to around 20% within a few weeks of them arriving here.

[skyhuck]

From the table you posted logs at 25% V ones at 15% is a drop of 14% not 40%. I was being a bit pessimistic saying ours are at 25% as in reality on inspection most are at 20% ish but 15% is unachievable at this time of year unless we get a prolonged easterly which is very rare. Fog is our problem but the hill variety. But fog or no fog external RH is normally in the nineties. In the very dry late Autumn the best ours got down to was 17%. You are very lucky having a climate where you can air dry down to 10%. Guess you must be effected by the Foehn effect?

 

We could buy in kiln dried logs but whats the point? We don't have a shed that could be humidity controlled and I don't have a single customer who stores there logs in their house or humidity control shed. All that extra drying would be completely wasted and logs would go back up to around 20% within a few weeks of them arriving here.

 

Has anyone ever actually done any tests to show this is actually the case?

 

It take a lot longer than a few weeks for timber to become dry, is the reverse procedure really so much quicker?

[Stubby]

I had logs that were split and put in an outside log store in the spring from round that had been sitting for 3 years . Some of this came down to 11% moisture by mid summer ( according to my meter ) but was back up to around 20% buy the time I came to burn it .

[skyhuck]

I had logs that were split and put in an outside log store in the spring from round that had been sitting for 3 years . Some of this came down to 11% moisture by mid summer ( according to my meter ) but was back up to around 20% buy the time I came to burn it .

 

Is that a reading from the middle of a freshly split log?

 

I would expect the outer inch or so to change relatively quickly with the ambient humidity, but find it hard to believe that the moister goes in very far, very quickly.

 

I also think deferent woods will behave very differently.

 

Our home was very, very damp when we first moved in, it had never be properly heated. I fitted a huge out door boiler and many extra radiators. I heated the house 24/7 for three and half years, before it became dry and no longer needed heating in the summer.

 

We have solid walls, with no cavity. I believe I had to completely dry the walls from the inside out, when the walls were damp capillary attraction brought rain water into the walls, once dry any rain only penetrates into the walls a little and then finds its way back out the same way when the rain stops. Water normally follows the path of least resistance.

[richardwale]

I had logs that were split and put in an outside log store in the spring from round that had been sitting for 3 years . Some of this came down to 11% moisture by mid summer ( according to my meter ) but was back up to around 20% buy the time I came to burn it .

 

Exactly. Happens to everyone who stores firewood. Drier in the summer, damper in the Autumn and winter, it's a fact.

So essentially stoves suppliers only suggest kiln dried logs or wood that's 18%.

Commercially air dried firewood will get to 20% rarely less. This will burn perfectly well.

It's very annoying when customers are misled to thinking anything over 18% is simply not good enough and God forbid, don't ever ever ever even think about softwood.

[dig-dug-dan]

I delivered a load of logs to a pub, having carefully seasoned them, stored then dry and monitered their moisture content, only for the landlord to announce he woule leave them out in the rain before he burnt them as they would last longer on his fire!

[Mortimer Firewood]

I delivered a load of logs to a pub, having carefully seasoned them, stored then dry and monitered their moisture content, only for the landlord to announce he woule leave them out in the rain before he burnt them as they would last longer on his fire!

 

If a landlord buys logs off me I give um a bigger load and ask him to keep um dry put your card in a nice bit of a feature by the fire place and you get return out of it. We supply a local restaurant that have two360 degrees log burners they have got me loads of trades over the years

[dig-dug-dan]

Good idea, but log sales for me is just a sideline, and I sell what I have left once I have kept all the conifer for my fire. I generally sell around 10 truck loads, then thats it. No space to store much more

[Alycidon]

From the table you posted logs at 25% V ones at 15% is a drop of 14% not 40%.

 

3700kwh per ton to about 4500 kwh per ton, my error, point taken.

 

A