Not my favourite time of year. Last time I posted we were enjoying the end of a warm Autumnal November. Now we’re at the end of a drenched December and January that seems an impossibly long time ago and everything is just so Wet!
It’s been unseasonably warm (I’m told we should learn to expect that as the climate changes) and that doesn’t help at all as all my carefully prepared stacks of firewood have been exposed to continually moist air.
The must-have present this winter for the firewood hunter gatherer of the family is the book attractively entitled ‘Norwegian Wood’ a well written story of woodsmen, firewood and beautiful Norwegian piles of firewood stacked outside and covered in snow.
But here in the British Isles our firewood no matter how carefully split, stacked and dried during our relatively long summer is exposed to moisture laden gales – now replete with everyday names. Today we’re enjoying ‘Storm Henry’ at a relatively balmy 12 degrees above zero (C).
The result – my carefully seasoned, split and stacked firewood is shockingly wet! Almost 30% on this piece of oak chosen at random from the stack outside my front door. That’s a lot more water in the log than I’d like to have – 300g of water in a 1kg log and all of that has to be ‘boiled’ off up the chimney. That’s all energy not available to heat the house, resulting in a cooler stove and potentially more tar blocking up the chimney as inefficient combustion at cooler temperatures mixes volatile chemicals and moisture.
So what went wrong? Nothing other than our British ‘maritime’ climate. We just can’t do Norwegian Wood over here. It’s too warm and too moist. Wood is hygroscopic – in other words – it will absorb moisture from it’s environment. If the atmosphere is above zero (C) and moist then dry wood will become damp. There is an equilibrium moisture content, and at a few degrees (C) with the relative moisture content of air up to between 90 and 100% (the air is saturated with moisture) as it has been for months now. Then my air dried logs will be returning to somewhere over 20% and perhaps as high as 30% depending upon how quickly the moisture is absorbed and how long it stays moist.
What can I do about it? Not much outside. With so much rain and overcast days there is little hope of using the sun to dry the wood. Even expensively (environmentally as well as financially) kiln dried firewood will become damp in this weather. The same applies to the net bags of logs left standing outside filling stations or garden centres. If they weren’t damp when they were delivered they will be by now.
All I can do is ensure that I take my logs into the house and give them a day or two beside the fire (but not too close of course) before I burn them.
By chopping my firewood into smaller sizes and letting the warmth run through them I can reduce the moisture content to below 20% which enables a more efficient combustion in the stove as well as reducing the moisture released up the chimney.
So don’t forget to bring your logs inside at least a day or two before you need to burn them, chop them up good and small (you’ll get warm all over again) and run your stove hot enough for efficient burning. But most of all I hope your logs are nice and dry wherever you are burning them this winter!
Woodlandantics Blog 