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Thinking of a wood boiler. Am I mad?
 Started by  simBad
 24 Jan 2009, 7:39 PM

My old oil boiler has just about had it and I'm considering one of these new high efficiency log or pellet boilers. i have access it a source of wood but I would really appreciate some/any feedback from people who are already using them.
Two concerns really:
1. How much wood am I going to need?
2. How controllable are they and should I consider installing one if I am out at work quite a lot?
Obviously my concern stems from the oil crisis of late last year but although things have calmed down a lot wood appeals to me as the right local type choice but would it be a rod for my back?
Forest fruit deep frozen??
Do you mean, are there areas that are not sawn down, I do believe most of the Swedish forest is used, although due to the very short growing season in the north, it takes perhaps twice as long for them to reach maturity, something like 120 yrs old
I mean the berries and mushrooms picked by professional pickers in the forests of Sweden after the fallout came down but before the picking of forest fruits was banned by the government. It was deepfrozen, by order of the state.The sale of these fruits was banned for many years, but people who's job it was to pick berries and mushroooms still picked them. The state 'bought' these fruits in the after years of the fallout and stored the harvest in deep-froce containers. Similar to the other Scandinavian countries. As far as I know this highly radioactive waste is still stored.Any information on the issue?
An interesting snip from a very long PDF file on chanterelles.
Mushrooms are known to accumulate and concentrate toxic metals (Gast and others)1988, Obst and others 2001, Seeger 1982, Stijve 1993), a pertinent health concern
for those who eat chanterelles from polluted areas. Grzybek and Janczy (1990) found
that lead and cadmium levels in C. cibarius were lower than those in other edible species
from the same site. Likewise, golden chanterelles collected in northern Europe
accumulated less radioactive cesium-137 from the 1986 Chernobyl nuclear accident
than many other species of edible mushrooms (Danell 1994a). It is possible that some
heavy metals in fungi might not threaten human health, however, because Schellmann
and others (1984) showed that cadmium and copper bind strongly to the indigestible
cell walls. Chanterelles collected from the relatively less polluted natural environments
of the Pacific Northwest might enjoy commercial advantages if their wholesome origin
is emphasized.
Otherwise I have no info regarding the storage of fruits and mushrooms, although they along with forest meats were not on the market for some time, but this was only from an area around Gavle, where the "cloud" came in over Sweden. The south and the north were not affected by fallout, that is as far as we know.
Even the poisonous mushrooms Morels are still picked AND sold, and are a real delicacy, if prepared right.
To the OP simbad:
Make sure you have a heated and sheltered place to keep your timber dry enough to be used in a legal manner.
Wet timber is not a legal fuel, you're not allowed to burn it.
Dry timber means 10% moisture content.
British fuel timber-stored outside in winter time-will have more then 205 moisture content. Illegal to burn, unless your neighbours aren't protected by various EU laws.
The efficiency of boilers and stoves is greatly reduced when burning wet timber. Manufacturers who state an efficiency of the combustion process are doing so assuming the timber to be burned has not more then 10% moisture in it,so you'll never achieve what it says on the pack if you burn timber in winter which had been stored outside.
10% moisture content is what furnitures show, stored in a heated and ventilated place.
The 10% moisture rule is laid down by EU law.
Pellet manufacturers have to stick to this rule if the want to sell their product.
However if these pellets are stored outside they will take up the moisture from the air, turning a.) an illegal fuel and b.)into a sawdust mud. Not suitable to feed a boiler/stove.
So it is not only you who is mad (smiley) but those who show no regard to the laws of physics and their and their neighbours health.
"...more then 205 moisture content."
Means: " ....more than 20% moisture content."
To fridihem:
What do the Swedish rules say about the legal limit of water content in timber (derived) fuel? And why is this limit set?
"There's no waste. It's all product," he says. "What we have that's different is an engineered product." It won't float, for example, weighing in excess of 40 lbs/cubic metre. At 9,000 BTU/lb, the pellets produce 2,000 BTU/lb more than natural wood. The pellets are about 1/4" in diameter and 1/2" to 3/4" long. They have a moisture content of about 4.5 per cent.
This is an extract from a producer of pellets for the Swedish market
Is there any legal framework covering the moisture saturation/water content of timber fuel for Sweden except the general EU enviroment laws/trade regulations?
I can imagine the swedish regulations are even tighter, but I don't know. Any comment or link, fridhem ?
Thanks for the very interesting link, fridihem.
Allthough 'only'a market analysis prepared on information delivered by the industry this document delivers a lot of information.
For example about the moisture content in ratio to it's potential energy contentent:
On page 4 it shows a table presenting the 3 different quality types of pellets:
Grade 1 (EU standard) is not allowed to have more then 10% moisture and has a theoretical energy content of 4.7kWh/kg.
Grade 3 (industrial quality) is not allowed to have more then 12% moisture content and delivers only 4.2kWh/kg....
Which means a loss over 10% of energy per 2% increased moisture content.
So the OP, planning to burn timber with a moisture content of more then 20% (ouside-stored timber, stored under British winter weather condintions) will have a reduction in his fuel efficiency of over 50%.....
If one has to pay per weight then better turn the water tap open(smiley).
So the answer to the OP's question ("am I mad..)is a clear: YES!
Not only a lot of money and energy will be destroyed by using this fuel but also a high health risk put onto all breathing creatures in the vacinity of this house.
Interesting also on page 15 of the document: only 8% of the logged timber is left in the forrest, clearly demaging/exploiting the top soil, an unsustainable way of forrest managment. See also this statement from the same document:
The Swedish forest industry
The importance of the Swedish forest industry to the prosperity in Sweden as well as to the
pellet sector is substantial. The problem is that even today when the forest industry is
booming, the competition for its by-products is increasing. Despite of the high annual forest
growth (more than 100 million m3skI/year) and an annual cutting of about 92.4 million
m3sk/year (Swedish Forest Agency, 2007), the forest resource cannot meet the demand for
forest products. Some researchers argue that Sweden must revalue the forest resource and take
advantage of its true potential by changing the forest politics and the way the forests are
managed. This, they argue, can be done by using other techniques such as fertilizers and
foreign tree species to increase production (Johansson et. al., 2007), methods that may be
perceived as rather controversial in Sweden.
Also we learn from the document that pellet prices as well as electricity prices have increased by 60% within ten years.This increase will increase, meaning the prices will develope exponential with increased demand and decreased output.
Hardly to be called a cheap fuel for the future.
Storage at Lidhult.jpg (180Kb)  
It was interesting wasnt it. I remember when I bought my first pellets stove in 1999, the price of pellets was only one third that of el for the eq kws, and as I was running on El radiators, I found the stove to be well worth it, but today, both el and pellets have gone up in price, but the saving with a pellets stove is still about 3 to 1.
Jan 2005 we had a violent storm, which was called Gudrun, it lasted for about 6 hrs and went across the south of Sweden in a band about 50 miles wide, it felled 170 million trees, and people were without el for up to 5 weeks and telephone for 7 weeks. The attachment shows what only 2% of storm damaged tree storage looks like.
Yeah, I have seen similar pictures from France and Germany and Austria.
There are still lots of hectares of destroyed timber plantations left since Lothar and Gudrun and many other stormy events. Usually the plantations planted for a fast profits are hit hardest, the natural forrests being more stable, self-healing and recovering without interferrences(monetarian drains) by humans.
When Lothar swept through France(Europe's largest pine forrest in the Bordeaux-Medoc area was virtually laid flat)
the at-the time president candidate Sarkozy promised help to forrest owners. They voted for him and went bancrupt.
These forrests in France can't be insured anymore. The species of pine-trees there were a "foreign species" originally from the French Mediterean coast, planted at the Atlantic coast since 200years.These forrests never were able to be managed in a sustainable manner, either they burn down or the storms sweep them away or the beetles eat them.
Which reminds me on the idea published in the link from Swedish pellet industry,suggesting the large scale planting new species.
I would say timber as fuel for power plants or stoves/pellet boilers is bad idea if it can't be got for freein the form of sawmill waste, originating from a self sustaining forrest.
We better insulate our buildings, using what is there, the sun sends no bill.
Hi All
I am researching buying a wood fire/boiler to reduce our need to burn gas. I have found a 12kw one for 630. Is this value for money? Where is the best place to look?
What other products would I need to buy, storage tank - which one, metal header tank (due to possible heat expansion)
Basically any help or advice appreciated.
I Am really new to this, but would like to ask where do i find out what wood fires / boilers are good value for money. I have found one that generates 12 kw for 630, is this good?
I would like to reduce our gas and electric bills and use renewable energy at the same time. I have read many sites on the internet but they only tell you what they want you to know. Is there an idiots guide that explains the boiler, the pipework, storage tanks, header tanks (due to possible over expansion)etc
all advice appreciated, thanks
i have an esse ironheart, which is running well, providing lots of heat and weekend food
can't keep it going overnight and am thinking of using "blazer" logs or equivalent
any views on these fuel logs or alternative, non- fossil fuel ways to keep the thing going overnight
Hi Geoff
I'm envious of your Ironheart.
Re: Blazers. I have been using some recently and they are very hot indeed. I think you might keep it in with these. have you talked to Esse for advice? My feeling would be (if the Blazers don't stay in) to use large pieces of ash or oak last thing at night on a small bed of embers (and you may already have tried this).
Meanwhile tell us more about the Ironheart, what do you cook on/in it and is it doing DHW or rads as well as cooking. If only they did one half the size...
thanks julian
ironheart is great, mainly use as direct source of heat. cook stews/ roasts and kettle on top
tried cooking other things on top but as i have it in the recess from old range cooker steam/ spashes etc had nowhere to go
very attractive bit of kit
could try to do attachment if you'd be interested
I am a partner in a new UK business called Eco Angus Ltd.
We are now the sole UK contract distributor for Eko-Vimar Orlanski on their Orlan Super wood gasification boilers (50,000 sold so far through Western/Eastern Europe and America).
We use DZD Czech Republic NADO/NAD tanks for Akvaterm Finland Accumulation tanks.
We are looking for experienced installers of wood gasification boilers or installers who would like to look at installing wood gasification boilers in future.
One of the partners is a Hetas qualified plumber who can run training days if required.
Our website is
We have a grant system for Ireland (Greener Homes under SEI) and are in the process of obtaining MCS and ECA/ETL through Carbon Trust.
If interested can you please let me know via
I would like to find out more about the Bulgarian Prity stoves...I know this is a slightly different topic than what has been discussed immediately before me in this thread. so do jump over me (metaphorically speaking of course) if this does not interest you as a subject. Or else you could go to my new thread...headed Prity Stoves...if you know something about them or any like them....I can't find any other wood burners similar to them in the UK....!
The challenges of making a house more sustainable and energy efficient are documented in the Evelyn Eco House website:
It seems that they decided not to go ahead with getting a wood boiler, though perhaps they would have if they were living in the property rather than renting it to tenants. Steps they did take included a SolarUK solar hot water system, cavity wall insulation and installing an electricity meter.
As a supplier in answer to the original question we would work on about 20% of the rated kW output as the amount of fully seasoned wood you would use per year.
This is based on a boiler rated at 92% efficiency.
For a correctly sized boiler we would estimate a burn time of between 10 and 12 hours on wood of around 15-20% humidity.
As far as how controllable they are and being out at work i would say this...most boilers will have a control panel to set the temperature for your water jacket in the boiler which ultimately is the contribution water to the accumulator tank.
If you are out at work then you would knock dowm the required temperature on our control panel and this would put the boiler in wood burning mode rather than gasificaiton mode for a greater percentage of the time.
This would ultimately give you a longer burn time.
When you get back you would increase the temperature of the control panel and put the boiler into gasification mode until it made temperature.
Without being advertorial we cover htis on a video on our web site;
The reason i add this as there is hardy anything on the world wide web showing this.
I hope people find this informative.
If an advertiser claims to have wood boilers available
".... rated at 92% efficiency.... " -as the advertiser winterbourne does in this year old thread- then show him the door.
There is only 1 condensing boiler running on wood available in the EU.
A non-condensing boiler simply can't achieve an efficiency rate of more then 86%.
And if running in a modulating modus (with changing flow temperatures) the stated efficiency can't be achieved as well.
The advertiser Winterbourne doesn't seem to understand what the stated efficiency rate means, therefore all his advertising claims have to be taken as, well, as advertisings. Not more.
Ask an energy advisor before deciding on a heating system.
Running a log boiler in non-gasification modus might be illegal in your area. Or will become so very soon.
I dispute this.
The manufacturer is ISO9001 ISO14001.
The product is CE registered TUV approved and Hetas approved.
As Eco Angus we are in the process of approval under MCS (Microgeneration Certification Scheme).
I have the full test reports for our 18/25/40/60/80kW wood gasification log boilers tested against EN303-5:2000 by an Independent test house SZU Czech Republic
The measured calorific efficiency by either the direct or indirect method is measured at 90 to 92% depending on the size of the boiler.
If anyone is interested in one of these boilers i am happy to e-mail the full test report for their perusal.
Heinbloed....could you not of whispered me first to check before stating this claim?
Well, winterbourne, the laws of physics do not have to be whispered. This is the 21st century.
About the efficiency of stoves or combustion apliances in general:
A fuel efficiency is meassured by calculating the thermal input minus the thermal waste.
With the stove or boiler the thermal input is the fuel and the waste is the energy contained in the fluegas.
Some continental European standards (not all) don't adhere to this logic.
The British standard does.
Check out the reports from the TUEV. They give you a flue gas energy content ( volume and temperature) as well. If you can't read it I'm fluent in German and will translate.
If this outlet gas temperature is higher than the inlet temperature there is energy blown up the chimney,wasted.
The German standards (to which Tchechian and Austrian standards adhere to) are saying that a fluegas temperature of ca. 250 degrees celsius MUST be reached. To avoid taring of the chimney, condensation.Poisoning of the inhabitants.
They start to count the fuel energy efficiency at this base.
This results in the absurd situation that a condensing boiler reaches under German standard a fuel efficiency of 106 % whilest the very same boiler tested under British standard will reach only an official SEDBUK efficiency of 92%.
Both are the same boilers, tested under the same conditions. But with the difference that the calculation done under UK standard is correct. And the one under German standard isn't.
If you sell a combustion device in GB you MUST state the fuel efficiency. The British fuel efficiency.
So saying a timber fueled stove or boiler will achieve a fuel efficiency of 90% or 92% is a straight ly. Otherwise it must be a condenser, an illegal device because the risk of a chimney fire would be there, due to tar deposits.
Quoting these ISO standards when talking about fuel efficiency is rubbish.
So are the other safety certificates.
Show us the certified British fuel efficiency report.
There is none, isn't it so?
What are the min. fluegas temperatures stated? You see....
Tell us where the condensate(the water-tar-ash mixture which will inevitable occure from a 90% fuel efficiency onwards )
is supposed to go with these boilers or stoves.
I can't see a condensation trap with these devices.
Contact the SEDBUK homepage to find out what the relevant standards in the UK are when making claims about fuel efficiency.

I just checked the home page of this boiler sales man:
There is no British fuel efficiency certicate with these boilers.
There is no condensing trap.
These boiler don't even reach 85 % percent of fuel efficiency in my opinion, but much less.
It seems that we are at slight cross purposes and hope to clear this up.
I am stating the calorific efficiency via the direct or indirect method and maintain 90-92%.
If you are asking for the gross efficiency at nominal output these readings are between 82.4 to 83.0% and are in the same class as Frohling/Winhager/HDG
Heinbloed....please provide your e-mail and i will happily send you a full test report.

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