mikeyne

Just wanted to say thanks for all the replies! We got sorted and Billy and Steve have just left after a lot of hard work today. Billy's Farmi WP36 handled everything we threw at it. Everybody got stuck in and we got through a great amount.

Well the wife just said we should get involved in the stacking so this could be a faster job than I thought. Also, I'm not used to processors as we currently have a bit of a more manual approach, but they do seem to chuck it through quickly! Would 20-30 tonnes a day seem like a lot?

Thanks John, that's great to know.

This year is proving tough to find the time to work on our wood supply and I was wondering if such a thing as a mobile processor and crew existed for hire in the North East for a one off job? We've got about 20 odd tonnes of semi-seasoned mixed hardwood (a lot of beech in it, some sycamore, some birch) to ideally get cut and split up this year. It's in 3m lengths, pretty straight but a mix of diameters from 6 inches to 18 inches. We also need it cut to 60cm lengths (so not the usual) and then stacking tightly in a Poly Tunnel by hand. Ideally, I'd like to hire a crew and a processor for a couple of days work and wondered if this sort of thing exists and any idea on what the going daily rate is? Cheers, Mike

Sounds like you have a plan. Poly Tunnels are great for drying the wood. The lift sounds like an interesting project!

I'm in a similar situation to you regarding your setup but with about a quarter of the throughput of wood needed (must be the double glazing ) and we've been doing it for a year. I can't really comment on the chainsaw question as there are others way more qualified but I've got some comments on the process. We processed about 40 tonnes with family labour and it took us around 5-6 days. It's hard physical graft and I already know next year will be harder to convince them to help, plus with the best will in the world I doubt we will process at the same speed as someone being paid to do it - whip cracking is hard to impossible. I also struggled with making sure they were safe and watching them with eyes in the back of my head. I've seen too many injuries through carelessness and chainsaws frankly scare the crap out of me. I'm confident I can manage wood processing safely myself but bring in a set of people with less experience and it raises the risks exponentially. I spent more time thinking and watching them while I was handling a chainsaw (no one else is allowed to even pick it up), and that inevitably reduces my effectiveness and focus on the job and increases my own personal risk. People also do not know just how dangerous powered machinery is. They get desensitised to the danger through repetitive use. So I tell my sister that the person operating the splitter is the only one who can place the wood on the splitter because only they can know where their hands are at all times, and she must never touch the wood to pick it up, then I see her later forgetting and helping. It happens. I'm painting an overly bleak picture as I think we did a good job and were safe and more importantly got safer as we progressed, but it is a tense time and not a funtime family activity. It sounds like you are spending a lot of time thinking about the process which is exactly what we did. My main learnings mirror what a lot have already said: Handle wood as little as possible, use a lift / front end loader to place the cord wood onto your choice of processor, use gravity to help move it (we use a ramp from the end of the processor that runs down at a very shallow angle to the bed of the splitter - easy to drag the round wood along it without it rolling too much). Try and process as close as possible to the wood store stacking area. Use stillages if you can to move the wood around the site and end up next to the boiler. I'm really pleased we bought a decent splitter that will last and I know will handle a lot. I'm not sure how you are planning on seasoning but 100 tonnes will take up a very big area if you want it to dry with lots of air movement through it. The best advice I ever received was try and have two years supply and forget about it, by the time you use it, it will be perfect. So that's 200 tonnes storage space... I've also not seen you mention the Biomass Suppliers List which you will need to register on. If you are a processing your own wood then as a self supplier, but if you are buying cordwood in you will need to register as a producer-trader and then "sell" your product to yourself on a quarterly basis. There is a lot of paperwork with the RHI scheme.

We went for excessive ventilation, it's got a 70cm netting strip all the way around all the sides at the base and netting in the doors at head height, plus I never got round to putting the main doors on yet so when the wind blows it does get inside . I figured there is no way I could control the moisture in winter, it'll be as damp as the ambient conditions outside but at least the wood wont be getting rained on, and if we have some dryish days, then the good air flow should hopefully keep on top of it and maybe even dry it again. I used to store wood in a shed with no ventilation but lifted off the ground and no double stacking. It used to take 2 years to get to the same condition as the wood in the tunnel this year that has taken 6 months. Air movement is everything.

I got it off Wikipaedia: http://http://en.wikipedia.org/wiki/Equilibrium_moisture_content For the cracks in my logs, I'm assuming that they took a while to develop over the summer and now we are heading towards the cooler wetter months, the wood is regulating as you say and they are closing up. I suppose this has an unexpected benefit as it closes the surface area available on the logs so they will absorb moisture at a slower rate. Regardless, even though they have closed up the surface moisture content at the end of the logs is still a nice 18% so the poly tunnel is keeping them pretty dry even in winter. Agree it is wasteful to dry below 15%, as winter storage will generally overide it. I've found the poly tunnel has taken green wood at around 45% moisture (sycamore and beech) and taken it down to an average of 25% over a period of 6 months. But this is for logs that are 60cm long and densely stacked in 4 rows. There is lots of air flow around and through but it is not as good a drying environment as it could be (the logs on top got ridiculously dry in a few months). I'm hoping that there will be enough storage for two years supply so next year, the wood will be awesome, it's already good this year.

I used this graph when I was trying to work out what moisture content I should expect from air dried seasoning of our wood pile: Even in winter at 90% humidity (the black line), the wood should be stabilising to around 22% moisture. It does not take many dry days in summer to see the equilibrium moisture level getting down to 15% moisture (the blue line if we are really lucky). How long the wood takes at that state to get down to the equilibrium is the big question - I actually found a research study that had looked into this from the perspective of forest fires (how many hot summer days would it take to turn a forest floor into a fire risk) and this could be reapplied to wood drying. So if you held a kiln at such a temperature and humidity you should be able to predict the time to dry from one moisture level to another. I had a bit of a surprise recently when I brought some of the wood down into the boiler room. All summer it's been drying in a poly tunnel and cracking nicely, getting to 15 odd % on the outside and 25% inside if freshly split. However, I noticed that since the end of summer, the cracks have disappeared on the logs and when they come inside they look like this: But after only 11 hours in the warm dry conditions of the boiler room they look like this: It seems they will respond quickly to changes in ambient conditions.

Hi Marko, I'm burning cut and split logs not chip, so not what you are after I think.

This is probably too much information. Scroll down to the end for the summary! It ended up being a steep learning curve as I redesigned it three times before I'd finished but it ended up a lot better than I thought it would. The first thing I changed was to improve the recycle path of the air as it was getting constricted with the weight of the insulation on top. I pushed in a few long 100mm drain pipes and that helped a lot. After a few days, I opened it up and could see that the wood at the start was drying really nicely with lots of cracking and shrinkage, but the final wood at the end of the kiln was still wet (and starting to grow some nice mould!) - not enough air movement - so I bought a really big fan and put it where the dehumidifier was and left the dehumidifier at the start to dry the air from the recycle loop before it was then taken by the fan and blown through the stack. Unfortunately, that didn't work out so well as the dehumidifier was overheating because it was working in such a small space, it also didn't seem to be all that efficient. The final redesign involved moving the dehumidifier to the end of the kiln so it's own fan acted to pull the air through the stack. I then put a long flexible duct on the output of the dehumidifier and pulled the duct back through the recycle path. So the air was being pushed round by two fans one at each end of the stack and dry warm air was being delivered back to the main fan. As the drying progressed, it became harder and harder to drive the water out. I knew that there would come a point where the electrical cost of extracting each liter of water would make it no longer worth continuing. I was maintaining a temperature of about 20 degrees C (it was about 4 degrees C ambient) inside the kiln with the heat coming from the electrical power used to dehumidify and move the air, but I knew the dehumidifier was rated to work up to 38 degrees C so in the final week, I decided to really push it and put a small 1kw fan heater at the start next to the main fan. I knew the fan heater would blow my cost per liter sky high but I wanted to see what it would do to the water extraction rate. Each time I switched it on for about 8 hours, the temperature would skyrocket and I'd see a marginal improvement in water extraction but not much. After 19 days of running the kiln I stopped it and took it apart to see the result. The wood at the front was great. 6.8% moisture on the outside, 21.5% in the middle of a freshly split log. The wood at the back not so good: 11.4% on the outside, 33.7% in the middle. But the wood at the end only really started drying after I'd redesigned the kiln for the umpteenth time so it only had about 10 days of effective drying. Total cost to do this ended up being 375 units of electricity which on our tariff ended up being about £65. I ended up with 1300 kg of (mostly) dry wood, so the cost of drying it ended up being 5 pence per kg and when I bunged it through the boiler it burnt reasonably well and we got just over 2kwh of useful heat per kg so 2.5p per kwh for the energy cost (not including the original cost of sourcing the wood). So not too bad, but I know that next time I could do better. I would use the final design I came up with but instead of letting it build up to temperature naturally (it took about 5 days), I would bung the heater on straight away for the first 24 hours and give it an initial boost, then I would leave it alone. I reckon this would mean less energy used but all the wood moisture would be down to the best I achieved at the start of this kiln. It would probably also take only 14 days instead of 19. I would also switch the power supply to a cheaper economy seven tariff and save some money there too. My main learnings were (sound obvious in hindsight) Get the airflow as fast as you possibly can Make sure the air moves through as usefully as possible - stop it from going around the wood - pack air gaps. Get the kiln up to temperature fast and let it marinate. It could be very cost effective. I actually got really serious about turning this prototype into a functioning kiln that would be more permanently built but eventually decided not to pursue it for the following reasons: It is costly to build. The temporary plastic sausage and insulation worked well but ended up being destroyed when taking the kiln apart. You would either have to invest in better insulation than rockwool that can be easily reused, or build a permanent structure with very tight air gaps - I had grand plans for an insulated box which the stillages would be pushed into at one end and pulled out at the other (think a commercial pizza oven with the continuous belt). Controlling it is hard. The dehumidifier has an optimum operating temperature of 30-38 degrees centigrade, and ideally you want it to be working at this temperature from the start. This will give you the highest rate of water extraction per unit of electricity. But, because the kiln relies on insulation to maintain the temperature it will be heavily influenced by the ambient conditions. Basically, in summer, you'd have to be removing insulation or it will overheat - not very practical on a permanent structure. It's not the safest thing in the world. Every time I left it alone I wondered what would happen if it overheated and I started a nice electrical fire next to a big pile of dry wood. I had a fire extinguisher near it at all times, and had a continuous check of temperatures and humidity, but still breathed a sigh of relief when I switched it off. So fascinating experiment, but we've decided to go for the Poly Tunnel route!

I really wish that was the case, but the wording of the announcement to RHI folks: suggests that it is the using of and not the purchase date that matters. Which is a bit of a problem if you factor the time it takes wood to season into account. When I read that I phoned them up and asked them what I was supposed to do with my existing woodpile that has been sourced from sustainable woodlands but is busy seasoning on a 2 year cycle - they had no answer.

Thanks for all the advice. It's not new but it's been pretty well looked after until today, just cutting lots of round wood and felling a few trees. I've been sharpening by hand and it's not needed too much doing to it, but today it got hammered (I hate nails). I started sharpening on the saw but it was taking a while so I put on a new chain while I decide what I'm going to do with it (find the time to sharpen it properly). One thing I noticed was how amazingly great the first cut was with a brand new chain but also how it seemed to lose maybe 1-2% of cutting power within the first cut. I was cutting through a 15 inch Hawthorn ring so not the softest of wood. It really felt like hot knife through butter for the first few seconds and then it settled down into great but not amazing. I probably imagined it!

Thanks! It's just two but both on the same side. I'll get it sharpened and see how it does.

Hi, I need some advice. I was cutting up a thick old wooden beam for firewood today when I seemed to find every hidden nail and screw in it! Took a few restarts but I managed to find a clean way through eventually but not before blunting the chain a fair bit. So I started to resharpen it to find a couple of teeth had snapped clean off the chain! Is this bin time for the chain or can I carry on using it after doing a lot of sharpening?

It's a prototype so it's not pretty! I built a load of stillages to hold the wood and set them end to end to get the path of air through the stack: Then I wrapped it in standard builders merchant DPM to create a sausage and put the dehumidifier at one end with it's output entering through a taped on plant pot with it's bottom cut out (it was handy and I was running out of daylight!): I created the recycle for the air on top of the stillages using some more dpm and wood spacers so it flows from the far end back to the dehumidifer. I then built a wood cage around the dehumidifier so it would be "inside" the system and sealed the dpm around that. All totally air tight and more Jaffa Tape than I was expecting to use. You might just be able to see that the dpm in the picture above is ballooning out on the side! I'd got the dehumidifier switched on at this point and the positive pressure was making the air flow around the stillages, so I created a load of wooden straps to hold the DPM in against each stillage and force the air back though the wood stack. Then I bought some cheap rockwool insulation from wickes and wrapped it up so now it looks like a brown sausage (I calculated I needed 20cm ish of insulation around the outside to get steady state heat loss at 38 degrees centigrade inside and about zero ambient outside): I didn't bother insulating the base but I would do for the final design. It's not easy to see, but there is a bucket on the right that the water is pumped into through a plastic tube from the dehumidifier (it has a purge cycle every 6 minutes) and I've placed two sample tubes for the eRH and temperature meters at the start (right in front of the dehumidifier exhaust) and at the end (just before it starts recycling back over the top)

I've just built a prototype dehumidifier kiln with about 2 tonnes of split green sycamore in it (45-50% moisture content). I only got it started 48 hours ago but the data is already looking interesting. I designed it so the only heat input is the actual electrical power input coming from the dehumidifier unit (rated at 0.7 kw). Then I made it a closed system, totally airtight, with a recycle of air powered by the dehumidifier fan. Then I insulated it like mad. I really tried to build it to make the air movement all useful, so at least 95% of the air is passing through the stack of logs, instead of around the outside. There is lots of baffles and restrictions to make the air go through. The insulation is supposed to be thick enough that it will eventually operate at close to 35 degrees centigrade once it's warmed up. Its currently gaining about 5-6 degrees every day at the moment and it's already at 22 degrees so I reckon I'll be there in a few days. I'm shooting for 700 kg of water removal to try and get the wood down to around 15% moisture (any drier than this and our boiler gets a bit hyperactive!). It's a slow start as the dehumidifier spent a lot of time in defrost mode while it was dealing with cold air, but it's chugging along now. I extracted 7.5 liters yesterday and 11 liters today. It's rated to extract 58 liters a day in optimum conditions which I'm hoping to get close to. I was really surprised at how well the dehumidifier is at pushing the air through the stack, It's doing a nice steady breeze. Currently going in at 50% eRH and coming out the other end of the kiln at 98% eRH so it's definitely getting the water out! I don't have a clue how long it's going to take to complete the cycle but the cost is so far extrapolated to be 12.6 pence per kg of final dry wood based on the electricity meter and water so far extracted. I'm hoping once it gets up to working temperature that this comes down a bit as right now a lot of the energy is going into raising the temperature of the mass of wood.

Hi Jon, I've never accurately measured it, but it's going to be around 250 square meters. There is also an external building of around 100 square meters that is also coming off the same heat store so around 350 square meters in total. When we were sizing the installation we looked at the 45kw model but it just seemed a little too risky. Now that we've been using it for a few months it feels bang on right, 45kw would have struggled.

I'm in a similar situation but we have been running our boiler now for 3 months. Reading the thread is interesting as I'm living and breathing the heat calculations and seeing what reality is like versus expectations. Bottom line, you will not get 4kwh per kg of dry wood even if you have it at 20% moisture. We are burning 2 year really well seasoned hardwood which is measuring anything between 16 to 20% moisture. The tested efficiency of the boiler is 90% plus, but this will be in laboratory conditions. The actual tested efficiency of our boiler in a real life burn at it's hottest part of the burn was 85.7%. At the start of a burn and the end, the efficiency will be a bit lower. Then you have losses in the pipework between the boiler and the thermal store which even being super lagged will exist. We manage to achieve anything between 2.7 kWh to 3.0 kWh per kg so the reality is 75% efficiency when you talk about the useful heat you actually get into the thermal store. I'm curious why you have gone for such a large store for a 45kw boiler though? We have a 60kw boiler and a 3000 litre tank which work really well together. I was expecting to get 4 kWh per kg when I was planning the system so the real life result is quite different, but really happy with the installation! The house is toasty warm and not a drop of oil being burned. Takes a bit of work keeping the wood pile filled up but I need something to keep me fit!