openspaceman

I don't think we disagree on anything here. The question then is why do you want to dry stuff? Air (=solar power) drying is the most economical and seems to be the way many woodchip suppliers are going (stacking partially debarked roundwood and then chipping into dry storage). Has anyone a link for the LENZ system to save me unfruitful googling? Farmer Rod was chipping into a barn and then shovelling it about to expose fresh surfaces, I don't know what mc he got down to. Chip in a covered heap will dry but you must prevent the rising moisture condensing in the upper layrs re wetting. An earlier poster suggested a figure of £9/tonne but did not specify the before and after mc, we aimed for £10/tonne water removed in 2002.One of the big costs with the drying floor was the higher fan costs because of higher back pressure from chip compared with grain which is more uniform but this was not my field, we were drying logs which presented different problems. Chip looked easier because of the quicker throughput and consequential lower system losses. BTW creosote is a result of pyrolysis, the gunk in a chimney is a mixture of condensed tars and PICs and if the burn is clean they don't get produced. BTW2 openspaceman is a play on Viv Stanshall's song.

Which, in the context of this thread, puts you to a MAM of 8.25 and firmly in the requirement to use the tacho. As I see it the main benifit in the new rules if for those of us who drive transits with chippers more than 50km and less than 100km from base as all 7.5 tonners have tachos from new and it costs a lot (~31200) to retrofit a tacho.

The Hatz engined ones have 70HP so why would a PTO one need more? Anyway the throat is much bigger than a TP and best of all if you feed a rail clip through it it only breaks a few cheap blades!

Cavemen probably had a high mortality rate from inhaling smoke from dirty fires just as today indoor air pollution from wood smoke is the biggest cause of infant mortality with over 2 billion people still regularly cooking with wood. At least we have the opportunity to burn wood cleanly in a box partitioned from the indoor space and venting combustion products well above the air we breathe. Not to mention the step change in efficiency by doing so. Having written that you can go overboard with demanding dry wood and burned hot and fast a burner can cope with higher mc wood as long as the three Ts of temperature, turbulence and time are observed. Theoretically burning fresh felled wood would only cause a loss of energy of 14% over burning it bone dry *IF* it can be burned cleanly, and there's the rub, the evaporating of the moisture reduces the temperature to below what is needed in the absence of sophisticated heat feedback. I see little problem with burning wood 30% mc wwb and down. Muldonach is correct in what he said about a log of 30% mc wwb still losing moisture any time that the RH is less than 100% but this is only because at 30% mc the wood is still just above its fibre saturation point, a small amount of water is free and not bound to the cell structure. As soon as that is lost (and this free water is the easy bit to get rid of) then the remaining water is weakly bound to the cell structures. It is this that then remains in equilibrium with the ambient air humidity but because there is a small amount of energy in the bond it tracks slightly differently whether the mc is increasing or decreasing, this means that a given air humidity the wood can have a small range of moisture content difference depending on whether the air is becoming more or less humid, all absolutely insignificant in firewood but interesting to cabinet makers. A little moisture in the wood can moderate the rate of gasification which makes secondary combustion more manageable but this refers to mcs below which we see in my home environment. I'd be interested to see the rationale in drying wood chip as the particle sizes are generally small enough to dry them on the fly, When Tilbury was burning wood a government department that had been semi "privatised" were drying chip in an alvan blanch grain dryer that had had a second oil burner fitted, I considered this a bit naughty and a breach of the spirit of the grant aid for non fossil fuels being paid.

A bit lacking for ideas I see. I spoke with the local Stihl dealer and they wanted 250 quid for a new pot and piston. I aked them if they would hone the bore and just supply piston and rings but nowadays they will not even lightly hone bores. I haven’t seen any after-market offerings for this engine but would any of the other 44mm Stihl pistons be the same?

Different bit of leglslation; the letter refers to cases where a vehicle is pulling a trailer and the sum of the plated weights is greater than the gross train weight on the plate of the vehicle but the actual weight of the trailer is within this GTW. Currently a tacho is required as soon as the vehicle combination exceeds 3500kg apart from a few exceptions. So currently a 4wd pulling a chipper 31 miles from base to a pruning job for the driver requires a tacho next year it will not and he can work further from base. On the surface it is a hugely useful concession. I am not quite so happy about the prospect of 31 tonne ancient tractors and trailers with no vehicle checks running around.

Yes I meant 300kW. You are well into the realms of needing a permit from your local authority. I have worked on boilers of this size but was not involved with the permits. In fact one installation at Milton Keynes had two boilers next to each other, the 1 MW one burned only virgin woodchip and the 200kW one was an exempted incinerator. The two ashes were not to be mixed.

So your boilers are bigger than 300MW? Waste is defined as something needing to be discarded from an operation and the full definition specifies the circumstances when something becomes a waste, arb arisings are waste but the EA position statement, simply put, is that virgin wood (even though it *may* come under the definition of waste) will not be treated as such, subject to the qualifications I gave. Virgin wood does not include predominantly foliage, hedge clippings etc. So some vegetation will be waste and subject to waste controls. To burn this will require the U4 exemption or come under the waste incineration directive. It is possible to have even an exempt WID compliant incinerator but with woody material it would be limited, and capable of, only 200kW (40kg/hour) Yes as long as it is virgin wood and not hedge clippings, but the size limit still applies and the arborist doesn't need the T6 unless he takes it from the place of production and then chips it but a non domestic land owner would need a U12 or U13 to leave other vegetative waste on site. So even if it is not virgin wood vegetative waste may be burnt in the same boiler as virgin wood but does need a U4 exemption. As Renewblejohn has pointed out once you get into bigger boilers or treated wood it is s different ball game

Paperwork? If it comes in as virgin woodchip, the burner is providing useful heat, clean burning and less than 300kW(t) nothing. If the chip comes in as clean untreated vegetation waste with a transfer note you need exemption U4 I think, still haven't got my head round the paper chain once it's burnt.

No, I haven't warn a wrist watch for over 30 years.

Tyvek?

I've just checked with some Walbro spares and that is 13mm by 1.5 mm whereas the piece that did the damage is 8mm by 0.75mm

I made this up using the fan from a beer cooler and 12V wall wart. It seemed to work fine but I haven't got round to cutting a 100mm hole in the wall. Plan was to take from above the Jotul through to floor level of lounge, following your post I may rethink.

The only time I remember finding stag beetle larvae other than in a woodpile was in a lime stump like that.

The coincidence of the air filter being out and the fact that the big and small ends seem fine plus the fact the damage is from the inlet port makes me believe it was a tramp bit of metal in the carb housing but I cannot think what. I have had it from new and only cleaned the air filter, not done anything else on the engine. Anyway what thoughts about the prognosis?

I still prefer the simplicity of the mk1

Last week was unlucky but this week looks better... The story; I was asked to demonstrate strimming so dug out my 1993ish FS360 which I only use in the garden nowadays, it hasn't done much work as we were mostly harvesting those days. Ran through the start routine, told the lad to stand back 3m and started her up no problem. Cut a few brambles to clear the engine out of accumulated 2t in the crankcase but it wouldn't come up to speed, four stroking like the choke was half on. Thinking the air filter was clagged I took out the inner element and started it again, ran like a goodun but after a few seconds it started playing up and stopped. No amount of fiddling would get it going so I felt sure it had seized. I left it in the workshop saying I'd look at it later but curiosity overcame the fitter and he had a peer down the carb and saw scoring on the piston. See pictures of strip-down below. This shows damage to the ring lands This shows damage on the other side and the air inlet area of the piston. More detail of damage at inlet side This shows corresponding damage to the cylinder And this shows the culprit, a steel pin 8mm long and 0.75mm diameter It must have been floating around inside the air filter for a while but where could it have come from? I don't know whether the cylinder is recoverable and whether I would get away with just piston and rings? I'm also loathe to do anything without establishing what may have happened to cause the pin to get into the motor. Or shall I relegate it with the Makita backpack blower with possible faulty coil and old Tondu hedge cutter to the scrap and get some new Stihl gear... Seems a shame to waste all those microdots Stihl and Datatag put on for me!

I've got a 1985ish 960 (not used in anger for 20 years) if that's similar? Like the 280 the feed is vertical rollers and the disc is inclined rather than square to the feed. as an arb chipper. It produces a very nice chip from roundwood , doesn't feed lop and top particularly well compared with a modern chipper and has to be sharp ( unlike the GM which will carry on chipping with blades that are too dull for its own good. Springy stuff like thicket stage birch used to curl up in the dead area between the further vertical roller and the blade.

Quite The very fact that pellets hold together is testament to their dryness, leave them in a damp environment and they turn back to sawdust. The Sprout Matador ring dies had provision to add steam as a lubricant and prevented heat in the die, from friction, charring the pellets.

Some losses are inevitable in burning any hydrocarbon or carbohydrate simply because a product of the combustion is steam, and as has been pointed out steam takes away a lot of the heat needed to change it's state from the liquid. So fuels containing hydrogen have two different heating values, the higher one is where all the heat in the steam is allowed for (HHV) the lower ones just accepts the losses in the steam cannot be recouped (LHV). With natural gas condensing boilers the flue gas is cooled ( below 56C) by the heat exchanger to below the dew point of the water vapour and some of this heat is recovered from the flue gas into the heat exchanger, droplets of water are formed and run out the drain or are seen as mist. In general with wood this is not practical so the flue gases exit at over 100C. Burn wood that is wet and these losses are greater. The sums are fairly elementary but they should track the values in the link to the tables that were posted. The concept is simple, the LHV is in the oven dry wood (ash is fairly inconsequential with wood but not grasses) and any moisture from the fuel must leave as steam at the flue exit temperature and thus subtracts 0.75kWh for every litre of steam produced. So if the LHV of as sample of dry wood is 5.17kWh but it is burned at 50% mc wwb then each kg burned will contain 0.5kg of dry wood with an LHV of 2.585kWh but the steam will carry away 0.5 times 0.75kWh of this leaving you with 2.21kWh of heat in the stove. The difference between LHV and HHV is academic but as every kilo of dry wood burns to produce 0.55kg of steam the HHV will be 0.75 time 2.3 ( about 0.4kWh) higher than the LHV

I used to read about centralised control district heating in the eastern bloc and I thought the practice of opening windows to control heat was just a way the bolshy masses railed against the machine, then my mate, a sqn ldr with the raf regiment told me about the problems with the married quarters in germany and how this was the only control that worked at the time. These key worker flats were occupied with principally overseas workers but they certainly were not dumb, the fault was with the system and management not understanding the time constant of a few hundred tonnes of floor. I have dumb managers in my current place of work and they bring fan heaters into their offices and leave tham at 25C even when they go out, one has to experience the sheer wastefulness and environmental unconcern of utility veg management persons to lose all faith in society. I worked for the UK agents for two makes of boilers so did not get to know others. It looks like it is derived from the original Baxi crossdraught gasifying burner but doesn't have the water cooled throat. The Baxi was a commercialisation of a research project but I cannot remember the guy's name. Anyway the big advantage of gasification is in cutting down on excess air for the secondary burn plus this one seems to have some sort of lambda feedback. For me the extra capital cost and requirements don't stack up for RHI. I live in a small 2 up 2 down cottage and the Jotul 602 keeps me warm on un paid for wood.. If I lived in a 10 bedroom mansion set in its own grounds and woodlands... Evenso I'd still advocate picking upo a cheap stoker boiler from someone buying new kit to get RHI. I've seen some bargains. Yes his Esse range wasn't meant to power a full wet system.

Cornish WB has pointed to many of your problems but this last bit is significant to your original query. If it is direct then the turbulence from the return from the underfloor injection manifold will kill any stratification whereas a coil in tank will not. Also if the woodburner is feeding the top of the tank without back end protection (e.g. ladomat) then this can also de stratify. We installed a back up 25kW(t) pellet burner in a block of 12 highly insulated flats with under floor heating. The main heat source was supposed to be solar thermal panels. In fact the fluid logic and program were so badly implemented the pellet burner was held on almost permanently. The unmetered heat meant people in the flats tended to control temperature by opening windows and the constant call from the underfloor circuit wrecked strafication and kept buffer <50C so the pumps fro the DHW heat exchangers were inhibited. As the pellet heated burned in the early morning to get the buffer temperature up and there was little demand because the workers were at work the solar never cut in as the top of the buffer was hotter than solar could supply.

I think this bit is very significant, the glasses affect the seal, poor seal means a leakage path for sound and hence poor attenuation. I think this is why, despite wearing ear muffs from the beginning working with motor saws, I suffer from tinnitus.

I have this ancient hedgcutter with a damaged engine but the blades have little use and the gearbox is sound, seems a shame to bin it but what to do?

There was a retro fit kit for this consisting of a bottom bar in a slider preloaded with a gas strut which was supposed to meet the standard. I agree £2k is too expensive for obsolete kit, especially petrol engined.