Advice please: logs or chips

[Mycoman]

Hi, been following for a few weeks, everyone here seems like they know their onions (or talk a ruddy good game), so here goes with a first post: advice, please...

 

I want to put a biomass boiler in to my house - well, outbuilding. Home is a six bedroom 'big hoose', have two let cottages next door as well. (currently using fuel oil - red diesel - and spending a fortune to be lukewarm.) Therefore, I'm looking at an 80kw to 100kw system with accumulator tank, etc. This seems to be at the upper end of things for log boilers (wood gasification) and at the lower end for the more automated woodchip systems.

 

I have around 25 acres of unmanaged broadleaved woodland plus scope for a few more acres of planting, I have a quad and trailer and L200 pickup. I have a saw, an axe and my health. We're 2 miles from an industrial user and supplier of woodchip but we've an old and space constrained property, can't accept artic loads to the outbuilding.

 

Would I be mad to consider the log gasifier? Does anyone have experience of log boilers on this scale? Do log boilers work significantly differently to chip ones (ergonomics and feed supply excepted)?

 

Sorry if this is a ramble and too many questions but this will be a big investment and one I can't afford to get wrong (btw, a log boiler is a good not cheaper to install than all the automation gubbins involved with chip).

 

Thanks in advance for all help. M

[Tony Croft aka hamadryad]

not enough knowledge to help, but certain youll get a reply sooner or later, just keep it bumped if no replies forthcoming.

[monkeybusiness]

Great post - I'm genuinely interested to hear informed views on this.

[pembswoodrecycling]

I'll be interested in the outcome of this.

I would have thought that the automated system would be the way forward, especially if you want the "turnkey" benefits of on demand heating. Are they holiday cottages? With logs you may find yourself working day and night to keep the boiler going just for someone else's benefit. Takes a lot of logs to maintain 100kw.

Although both systems are a cost (chip more than logs) remember you will be able to claim the RHI which you can't whilst on fuel oil.

With my mechanical engineering hat on, it's much more reliable to have a big system running at a low output than it is to have a small system running at capacity.

Just my thoughts....

[Mycoman]

Great stuff already, thank you. Tbh, others' experience would be brill but the thoughts and educated guesses of Arbtalkers is just as good. What kind of questions should I ask salespeople, for example?

 

I had been told that it's better to have a smaller system running flat out than a larger one idling (esp with an accumulator tank). Any other views?

[pgkevet]

Playing devil's advocate:

 

I have an older, doubtless innefficient multifuel stove running on logs and with it's back boiler it can heat the living room well but only just take the chill off the rest of the house and I'm guessing we got through some 12 tons of timber this mild 6mths. And guessing again I'd reckon we'ld have used £2K of oil if running that all the time instead...but would have been toasty.

 

If I scale up those figures (more guesses) then 3-3.5K for a year here..so on your larger property and 2 cottages and a new efficient oil boiler...say 7K oil at current prices OR 40? 50? tons of wood for a year?

 

That's a lot of timber..don't forget to factor in the capital costs and running/replacement costs of saws, chains, tractor, storage, PPE to get that timber...let alone your time And the differences in cleaning/maintaining wood stoves compared to oil stoves and the amount of brash and chip waste you'll be handling.

 

Finally consider what happens from the viewpoint of risks to yourself in processing the timber and what happens if you get unlucky and unfit to go cutting it (age etc) especially if you say you can't accept external bulk loads. Could you earn more money doing something else with the time you'll spent cutting and carting?

[delabodge]

send nick channer a pm,,he knows abit about bio-mass, his farm runs on it,,and the four ajoining houses,,(I think)

[muldonach]

We heat a medium sized stone built house (4 bed, reasonably well insulated) with a 20Kw multifuel stove which runs a central heating system with a wrap around boiler. It has not seen a lump of coal for 15 years and works well - it is fired on hardwood thinnings and will eat 20 cubes of timber in the year.

 

Do not underestimate the space requirement for logs - I would guess that you would need a woodstore for at least 40 cubic metres in order to have seasoned timber available and you say you are space restricted.

 

Do not underestimate the work involved, 40 cubic metres will be 10-15 full working days out of your year by the time you, alone, fell, process, transport and stack the timber.

 

In order to feed your system you will be looking at starting at one end of your 25 acres and clearfelling it, it may look like a lot of timber now, in 10 years or so it will be gone and you will be looking for logs.

 

You may have a saw and an axe now, in a couple of years you will have a collection of saws, a tractor and logsplitter and probably a pile of brochures from processor sellers:thumbup:

 

Is your local chip supplier able to supply chip at a known moisture content? Can you get small quantities i.e. silage trailer or mesh sided car trailer?

 

Given your situation and resources I think I would be looking at fitting a woodburners in the lets especially if they are holiday lets, and in the main house - use the thinnings and windblow from your 25 acres to feed them and use them as top up heaters.

 

I would have no qualms about using a log boiler as well but would design the system to replace it with a chip boiler later - or just start out with the chip system.

 

 

cheers

mac

[MikeTM150]

Well I'll put my pennys worth in, i've just looked at putting an 80kw eco angus log boiler in to heat a large 6bedroom farmhouse with a lot of drafts and to heat the hot water in our milking parlour. The calculation i came up with i reckoned i'd be humping nearly 250kg of logs into it everyday!

 

So i looked at chip boilers and having an automated filling system, more expensive in outlay obviously and i'd have to buy a decent sized chipper to make me own chips. BUt its the way i'm going to go, cutting up and splitting wood and feeding a big log boiler was going to be very time consuming!

 

Sorry i can't be more helpful, but as previous posters have said, you may become a slave to logs if your not careful!

[difflock]

Hmmmmm?

Somewhere in the midde on this one.

Currenty heating near 4000 sq ft of 1995 built, with 1995 standard insulation, dwelling hoose.

We have always run a 5kw Morso in the front room, with "free" forestry to the rear of the house.

I installed a 40kw logburning gasifying boiler with buffer tank, under a NI grant about 5 or 8 year ago.

I did seriously consider the woodchip option but being unable to hire a suitable chipper and not justifing the purchase cost went for logs.

Previously running on 28 sec oil we were consuming about(but def less than) 2500 litres per annum.

Despite enjoying playing with an old tractor and new chainsaw, and still being a big fan of the Morso stove.

And despite the boiler being well able to heat the house.

Its a bloody bind.

this was all probably better expressed by PGKYVET, Muldonach & TM150 as above.

Tee Hee, whoever mentioned the ever growing list of kit werney wrang

Tractor (7really need another one)

Forestry Winch

Log trailer with crane

Just about to be delivered 17 tonne splitter with winch

Ditto PTO driven saw (hence justification for 2nd tractor)

Ditto a wee quite unnecessary 5.0m log conveyor belt

Plus...........sufficient sheds to keep it all under cover

And I Actually need another one o them too:001_rolleyes:

And sommat bigger than the current 2 No. 30' by 60 ft's I already got

Plus I really gotta clone another "me" to do all the manual work.

Hey, perhaps on reflection

HEATING OIL is really CHEAP

assuming reasonable insulation.

Cheers

M

Edited March 17, 2012 by difflock