openspaceman

Bearing in mind I don't sell or buy hardwood just collect for my own use, though in the past I did commercial work on dryers and chip stoking boilers, hence my interest in the science, I take what I can get, and don't turn my nose up at softwood. Felled in winter it can have a low moisture content and it does dry fast once split. Anyway the basic density of pine and oak from the blue book says 350 kg and 540 kg oven dry timber per m3. As pine is a slightly higher calorific value I would suggest when buying by cubic metre bulk loads the ratio should be about 70% the price of oak for similar heat output at the same moisture content. It will be lower for spruce.

@Stubby avert your eyes That's what I did too: 1kg log at 25% mc wwb contains 0.75kg oven dry wood with 3.875kWh thermal energy. The 0.25kg of water needs heating to 100C from 20C with 83.6kJ, turning to steam at 100C with 564.1kJ and then raising to 300C (I still think ~200 is more realistic) with a further 100kJ which adds up to 0.208kWh. This represents 5.36% of the energy in the wood. Allow the same piece of wood to dry to 20% mc before putting it on the fire means you have the same thermal energy but now only need 66.88+451.28+80 kJ or 0.166kWh that is 4.29% This is not a rigorous way of looking at it as that 5.17kWh not only varies between species, part of tree and season when felled but it is a Lower Heating Value, it already allows for the water formed by combustion of dry wood. I put something here a couple of years ago

I used 5.17kWh/kg for dry wood and my calculation gave 4.29% loss in steam at 300C.for 20% and 5.36% at 25%. I would like to know if people using flue temperature gauges actually see temperatures as high as 300C as it seems a bit high to me. Flue temperatures have to be above 100C at the chimney exit to avoid condensation with wetter wood but it would take a bit of working out what the dew point would be for dry wood, it would be less than 100 because the partial pressure of the water vapour would remain above the partial pressures of all the other combustion gases down somewhere below 100C. Of cause the chimney would be absorbing some heat and depressing the temperature of the column of flue gases, more so if it is not insulated. I use this as a feature, so the chimneybreast's thermal mass keeps the house warm after the fire is out.

You've got it Actually the latent heat of water does vary with temperature but your 0.6kWh holds good for the approximation we are looking at. When you burn wood it changes from a solid with associated moisture to ash (a solid but very small part of the original mass) and gases/vapours that go up the chimney at whatever temperature it leaves the stove, this mix of gases carries away heat from the wood that never gives you benefit as heat in the room. If the moisture content of the wood is high then you lose that 0.6kWh for every kg of moisture that goes up the chimney plus the additional amount of sensible heat it contains at temperatures above 100C. I guess most stoves run a flue temperature of 150-350C so this sensible heat of the excess water is also considerable. As you say wet wood is harder to burn cleanly, mostly because it quenches the burn, this shows up as smoke and particulates, Products of Incomplete Combustion, so some of the potential energy of the wood also leaves as PICs. Worse still is the business of excess air; because wood is a complex mix of substances that burn in stages we have to add more air than is what is needed to combine with the fuel to ensure enough oxygen meets the fuel to burn it out. Good wood stoves will use 1.5-2 times the ideal (stoichiometric) amount of air but this all has to go up the chimney at the flue temperature. Thus the massflow of products up the chimney consists of excess air, excess moisture plus the products of combustion (ideally steam and carbon dioxide, even burning bone dry wood produces water)). Worse still is wet wood tends to need more excess air than dry wood, hence increased sensible heat losses from the high massflow as well as extra steam. Bear in mind you need a stoichiometric mass of air about 6 times the mass of the burning dry wood because only 21% of the air is oxygen, the rest is nitrogen which has a free ride through the fire but still carries away heat up the flue, increase that with excess air and you see what a heat robber it can be. I think it does but it is a tiny effect only of consequence when discussing how much moisture is regained as dry wood picks up moisture again as the humidity increases in the winter.

Yes, the thing is there is much wringing of hands and wailing about using wood to dry wood but the physics of it is all the same , energy is energy whether we use solar heat for the drying or intercept it first on its way to gaining entropy and store it in a tree. The bigger argument is whether our value system, money and wealth, are good measures by which we make decisions. If not we need to come up with another one that functions as well as this. @gdh has put some numbers on it and it's simple to work out the difference in energy available in 25 or 20% mc wood but the rest is so many variables. One would need to know the parameters of the stove and the flue temperature to decide on which was better for which stove. From the supply side one would need to know the cost of covered space, seasonality of labour, cost of capital equipment etc. In practice a person makes simple decisions to run a business and one thing leads to another, if another business makes different decisions and as a result out competes the first then it is more successful, that's what drives capitalism, not basing decisions on what's good for the environment, that's what regulations do to keep everything acceptable to most of we also rans.

Does anyone know anything about the hydrostatic transaxle on these flails. The input pulley seems to have a bit of slop in it and I wonder if these things can be worked on or is it a case of running them to failure? @GardenKit or even possibly @PeteB

Interesting I've not seen one. When I tested our tracked chipper at 35 degrees for the CE technical file I found the Hatz engine oil pick up had to be factory modified.

For the time being I've drawn it at strimmer plastic but I still wear polyester-cotton clothes

Make sure the engine oil pickup doesn't get uncovered at extreme angles

My apologies I snipped badly and somehow it mixed up the attribution, I don't know exactly how but it is something to do with the quote selection feature when I highlight the specific bit I am replying to.

That too but I was considering the plastic one rather than the link he gave

No

It shows how there's always someone out there trying to catch out someone in the limelight, who'd want to live in that situation even if he's a pernicious creep.

I wonder where all the line worn off ends up

Drying does not increase the amount of heat from a given log, it has just driven off the moisture and made it lighter but releases about the same energy. If the piece of wood had not been dried some of its energy would be used to volatilise the moisture first, so the heat is not available to the room but goes up the chimney as steam. The more significant effect is than in turning the moisture to steam the fire gets cooler and burns less completely, hence more pollution. The bit about burning too quickly is rather spurious because in burning quickly it gives out heat quicker, if it's giving out more heat than required it's normal to turn down the air control to compensate. @Stere the late Tom Reed, a combustion chemist from america, produced similar results to that graph, I have tried to explain the reasons in the past. Firstly the flame on a wood fire is largely not premixed like petrol:air in a saw or gas:air in a gas burner, it is diffuse, the hot wood gases meet incoming air and diffuse into each other at the flame:air interface. The oxygen in the air reacts differentially to strip hydrogen from the gases and these carbon bearing remains glow yellow in the flame. If the conditions are good the hot carbon meets fresh air and burns out, if not it exits as soot. A premixed fuel to air has the gases and air intimate and the burn is simultaneous so no carbon left to glow and the flame is blue, this is how a gasifier burns a flame. We all know that if you throw petrol on a fire it doesn't burn blue and the carbon cannot burn out because the air is not able to supply enough oxygen, so we get black sooty smoke aka particulates. When air dry wood burns the heat from the fire raises the surface temperature of the new log, firstly to 100C as any surface moisture is driven off and then the wood pyrolyses evolving the woodgas and leaving char on the surface, the woodgas burns higher in the fire and oxygen combines with the char, burning it away and the next layer in repeats the process. You will see the moisture in the wood controls how the wood burns away. The less moisture the quicker the log can pyrolyse and burn because volatilising the moisture takes some energy which has to be supplied from the burning surface area Pyrolysis is slightly exothermic above 330C and below 440C so if there is little or no moisture present to rob heat a chain reaction can occur in the wood, the wood can quickly pyrolyse throughout with no extra energy from outside once the temperature is high enough to initiate pyrolysis. The wood then evolves more woodgas that oxygen can burn and like the petrol analogy soot is given off.

Generally where the utility is to supply more than one other property the utility will require an easement, this gives them more rights than a wayleave and will prevent any building or other works which might impede the utility on the land, it is irrevocable. As the properties are so recently sold there should be details of what rights went with the properties, rights can be quite specific

Math is american, maths still good English

It's interesting how different peer groups have differing takes on subjects. This forum is populated with a majority of entrepreneurial types who are spurred on by success, this leads us to tend to be right of centre, question our masters and be sceptical. I can look back of a number of political events, from vietnam era and onward and with hindsight and occam's razor I note that the most likely reason for things to have happened are simple and most conspiracy theories are propounded by people out to make a buck, or sell a news story.

Well of course the population isn't very locked down and there is enough contact out there such that there are still 2000 new cases being found each day. It points to there being some super carriers out there and certain situations, dense housing, large multi occupancy household etc. meaning that containing the disease in these situations is not possible. Everything also points to increased viral load leading to much more severe effect of the disease, so repeated exposure is likely more damaging.. I'm just grateful I don't live in a high rise, commute using public transport or aeroplanes or have to meet indoors with may people in my normal life, let alone now. The thing is legislation has to be one size fits all so we all suffer.

If you think about it general anaesthetics are avoided for most older people, especially those with cardiovascular problems, my mate died on the operating table at 62 because his heart gave out, so as an induced coma is necessary for a ventilator to be used... I'm confident they have learned a lot about treating this virus from avoiding ventilators to treating "sticky blood" and we don't know how the disease has triggered the most fatality, whether it's blood clots, cytokine storm, induced coma etc. There are plenty of 50 somethings on this forum that think they will not react badly to the disease, and statistically they are likely right but even Boris at 53 was dependant on good ICU care to get through it.

Always a good idea to save them wasting their time If it's an earth burn or ring kiln it's exempt from environmental permitting as less than 1MW thermal input if not dark smoke there is no statutory nuisance, still a polluting way to produce charcoal though.

No but I suspect those figures are from the total population less those who have died after being tested positive, a very disingenuous statistic

EA exemptions deal with waste, EA position statement said virgin timber is not waste. Are you using waste to make charcoal? Clean air act refers to dark smoke, are you emitting dark smoke? Combustion generally requires an environmental permit. There was an exemption for charcoal making prior to 2002 but I'm not sure about that now. Of course traditional charcoal making is polluting and emits greenhouse gases

How can anyone be considered to have survived the disease if they have never contracted it?

probably frost damage, where are you? The warm dry spring has caught a lot of plants out. The yellow leaves may indicate a mineral deficiency, keep it watered and wait and see.