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Wood Gasification (Log) Boiler Experience?

edited September 2007 in Renewable Energy
Over the last 6 months we have been considering the replacement our old oil fired central heating boiler with a log boiler as both our tank and boiler need to be replaced over the next few years. We have compared alsmost every manyfacturer available (Dragon, Atmos, Vigas, Froeling, Hoval, Baxi, Mescoli, Viesman, ETA, Herz, Biotherm, Treco, etc) and haven''t been able to make a decicion yet. Recently we started thinking about keeping the oil fired central heating and adding two wood stoves, one connected to the warm water tank.
My preferde boiler would be the Austrian ETA boiler which I have seen in operationa t various locations in Germany, but the boiler itself without heat store and other component, flue and installation is close to 6K, which is too much. The middle way would be a Baxi Solo Inova. Does anybody have any experience with Vigas and Atmos boilers, which are the most economically priced boilers. The pros are: renewable ennergy, affordable fuel the cons are: costly, not as instantly controlable as oil and gas, bulky and expensive to install.

Before finally making my mind up I was wondering weather anybody who has already installe a log gasification boiler would be willing to share their experiences and or frustrations?



  • I have a Baxi Solo Innova and think it is the business. I would advise against any log boiler that pushes the gasses out with a front mounted fan rather than sucking them out as the innova does with a fan mounted at the bottom of the chimney.
  • Do you have the boiler with or without the Lambda Control. They are are now available through Foundation Firewood but cost about £2000 more? Is it easy to adjust the combustion by colour and size of flame?
  • We've just finished fitting an Atmos boiler and it's excellent - very easy to light, heats up the accumulator tanks pretty fast and provides huge amounts of hot water and heating. I'd recommend it. The only thing is whether dealing with the logs becomes a bit tedious but we've got a local supplier who delivers one tonne bags and will cut to size, so we've just sorting out how to store it in a way that doesn't involve moving it around too much.
  • Get as large a store as possible and buy as much as you can in the summer and dry it for as long as possible. I have found in the last 3 seasons of owning an Atmos, no matter how "seasoned" log merchants say their wood is a few months in a store makes a world of difference!
  • What kind of money are we talking about for the Atmos boilers? Had a look at the web site and they look really good, but no prices...
  • advertise prices.
  • We have in the end decided to not go down the Log Boiler Route. For about the same money I can install a 4m2 solar hot water system (bought from LILI) with 259 litres triple coil tank, install a reasonable efficient woodstove with backboiler linked to this tank that will also heat about 50% of our house and replace our current oil tank and oil boiler with a condensing boiler and better controls . As I am regularly away for work this means that my wife who also works full time, does not have to fill the wood boiler everyday while looking after two children as well. But if we do light the stove in the living room this will contribute to heatig and hot water in the winter when the solar system is least effective. At some point I wil also install a second woodstove in the front part of our house which already has chimneys that will be partially rebuild next year.

    We don't reallly have space for a log boiler and heat store in our house and I would have to build am outbuilding which with my preffered boiler and connection to the house was getting closer and closer to the 15K mark, while current plans are closer to the 8-10K.

    There are a number of atmos boiler supliers in the UK have a look on ebay as well.
  • Sensible solution. We have the same problem and are in the process of upgrading. We have replaced a very old oil boiler with a consensing one, stage 2 is to change the hot water cylinder for a thermal store from Dedicated Pressure Systems ltd, this has solar and wood burner connections as well, that should give us the option of using either oils, wood or solar in the summer.
  • edited November 2007
    Sorry for delay
    Posted By: edwinvanekDo you have the boiler with or without the Lambda Control. They are are now available through Foundation Firewood but cost about £2000 more? Is it easy to adjust the combustion by colour and size of flame?
    My boiler does not have Lamda control and the environment is not likely to benefit from such a device as it throttles the burn and will cause more toxins to be released.

    An issue that has arisen is that my boiler has begun to easily overheat and shut down until the temperature falls off a bit which strikes me as bit dangerous. I think it is because I have perfected the art of wood drying and it is now too dry for the boiler but I'm going to call up the supplier for advice before I light up this winter.

    I have heard rumour that most high efficiency wood boilers are designed for wood with a moisture content of about 20-25%
  • The manual for my Atmos suggest a similar 15-20 Keith However I have experimented with briquettes typically 5 percent moisture with posotive results?
  • I do have a laddomat21 so I just realise the sillyness of my comment. DOH.
  • Kieth, what do you burn? All gardwood/softwood or a mixture?
  • Hi all.

    I have been researching these log boilers for a while now. I am on a budget so looking at Atmos, Vigas and Baxi. All of which are basic and robust and each has some negative stories attached (Baxi - problems with fuel size/overheating, Atmos - one installer returned to all the ones he fitted to repair [dont know specifics] and Vigas had a wall crack and the technical support from the imorter is limited). We have 11 acres of oak (which Baxi suggest not using all time due to high acid content?) so the less efficient machines without Lambda dont appeal and I run a small holding so am at home to light whenever. What seems to be solving the choice is getting a certified installer to come up with a price/system. Its been a nightmare. Early estimates look to be in the 7k region for a 25kW 1000l accum. system. We will do the dog work (shed building, hole in wall drilling etc), get a local plumber to install and get a certified installer to design with the plumber and commision to get grant. With the grant (£1500), plus the use of a new credit card offering 5% back for first three months and the local plumber saving travel costs it should be cheap enough. Admittedly 7k in high interest account would go a long way to paying for oil, but the wood burning is a lifestyle thing, I wont mind it going on a lot more often whereas I hate hearing the combi firing up!
  • Adam, only problem so far in nearly 2 years was the flue gas thermostat which was replaced fairly quickly by my installer and been ok since, a minor job which was a problem with a specific batch apparently.
  • I enquired about the minium required chimney heights and was informed that the Atmos needed about 7 meters and the baxi about 3? It is worth keeping this in mind when looking to install in a shed.
  • I have a 5 metre flue on my atmos with a rororvent cowl on top to help although it only takes 15 mins to warm enough on the coldest of winter eves. I shall however be investing in a twin wall flue and wold recommend yo do so.
  • On the flue front I understand that it depends on the situation (prevailing winds, obstacles etc) and the best way is to take advice, put it up and add an extra piece if you dont get an updraught.

    I am on the cornish/devon border and would be very interested in visiting any logboiler fitted to talk through the pros and cons and different set ups. I think each installer has his way of doing things and it being a fairly new thing over here they are all a bit different and I lack confidence in them. I need a simple set up as it will soley do one 3 bed building for hot water and heating, replacing an oil combi.
  • It depends a little on who you my upset with smoke, I have surrounding neighbours to consider and while there is considerable smoke on start up it lasts 2 mons approx and I have not yet had complaints even after pointing it out to them. Like I said the twin wall flue is a must.

    I have to admit I was just a bit brave not knowing of anyone who has installed one of these or being aware of this forum before I agreed to installation, however after just seeing heating oil crack 42p per litre I am a little smug I admit.
  • Keith, the moisture content of wood shouldnt have any effect as the first stage of burning removes this, the gasification burn (which is the hot one -several hundred degrees) simply ignites gases and wont be effected by wood water content. I would imagine that your set up is wrong (ie too small an accumulator, it not needing more heat, or some of your thermostats/setting are wrong). This is where I have a lack of faith in the installers of these things in the UK. Off to see a solar/log combination on tues which sounds sensible for those summer days.
  • I disagree adam, the dryer the wood, the hotter and faster it will burn
  • Large volumes of steam if produced during combustion force too much heat and combustion products up the flue so fast that the heat is lost before the heat can be collected= inefficient.
  • Its not so much that it wont affect the efficiency of the burn, but it wont increase the heat produced from gassification significantly enough to overheat the boiler and stop it working....the system should be set to remove this excess heat and a few % points of water content shouldnt have a serious effect on the running of the machine. It will slow the charcoal stage (ie first burn).

    The log boiler I saw yesterday had no accumulator, a back up oil combi, a solar system and an immersion system! As a result it needed a lot of tweaking to get it working. The idea being solar in summer, log in winter run at ticking pace till it was needed and the other two systems to kick in when temps dropped. Log boilers need a quick hard burn to capture all energy and a store to act as a buffer. The flue was really warm to touch even though it was twin walled leading me to think that not enough heat exchange was happening due to the low output temp of water from boiler needed for rads. It rammed home the idea of keeping it simple.
  • I agree sounds like too many sytems spoil the broth.

    The dryer wood definately makes a difference fills my accumulator in 3 hrs took 6 in my first nyeeve year of not properley seasoned wood!!
  • We bought our Atmos boiler direct from Germany - email, they will reply in English - and employed local plumbers which worked out cheaper than any of the certified installers even with the grant taken off. This also means you can get the slightly more efficient GSE version which they only sell in Germany.
    I agree that dryer wood is better, I got more heat yesterday from a pile of cut up floorboards and pallets from next door's refurb than I usually do from the not quite as dry as it should be hardwood logs.
  • Have an Atmos 32kw burner installed with 2000ltr Akvaterm accumulator, was just wandering is there anyone else using the heat exchanger coil inside the accumulator to transfer the hot water into their home? Everyone I talk to seems to be using the actual water contained in the accumulator tank to circulate around their homes and stay away from plumbing up to the heat exchanger coil. Just wandering has anyone ever had the system installed this way and then changed it or can give any advice please?
  • The heat exchanger coil at the top of the tank is for hotwater not heating! Using the water in the tank for your hotwater sounds like a recipe for problems with bacteria and legionella.
  • Don't actually use the water going round the pipes Johan. The heat is exchanged from the 2000ltr accumulator to the exchanger coil at the top which is piped to my house were the hot water is split to the radiators and the hot tank cylinder which also has a coil inside so no actual pipped water is in domestic use. When I had the system installed the way it was fitted is the actual recommended instulation method. I think the system is great and within 2/3 hours buring time the tank is approx. 90degrees top to bottom but I do find the radiators coming into the winter time could be a bit warmer.
  • Hello everyone

    I had an atmos 25kw log gasification boiler installed with a 1500ltr thermal store. The water in the store is pumped directly around the radiators and the store water is in turn pumped around an external hot water plate to plate heat exchanger which offers mains hot water up to 45 ltr/min. The equipment turned out very cheap The whole package included -
    1 x 25kw Atmos log gasification boiler
    1 X 1500 ltr thermal store
    1 x Ladomat
    1 x Hot water pumpstation (45lt/min)
    1 x Radiator pumpstation
    1 x Thermal saftey valve
    1 x 100 ltr expansion vessel

    £3650 + V.A.T This worked out the cheapest on the market especially when the equivilant hot water pumpstation is sold by DPS for £1200 + V.A.T

    Suppliers web address
  • Its good to hear a few people with experience of ATMOS boilers. I am mid way through installing a 15kw ATMOS twin boiler (combined Log Gasification and Pellet boiler) - so I can have the low cost of Logs and relative convienience of teh pellets. I bought the Boiler direct from ATMOS in CZ - who speak perfect English and could not have been more helpful - Plus the unit was hugely cheaper than anyone else I received quotes from in the UK or Germany. Go to ATMOS.CZ for info.
    I have not finished the installation yet - so can't comment on performance - but it looks well made and subscribes to the keep it simple principle.

    A couple of questions for those of you with a working ATMOS in place:

    How tall is your chimney/flue from Ground to top of pot? I have 5m at the moment (180mm dia liner) - but could extend the stack and put a pot on to gain a meter or so.

    I will run my system with a pressurised expansion vessel - where is the best place to plumb this into: on the cold side of the boiler inbetween the Laddomat and the boiler or into return from the heating circuit to the accumulator?

    Thanks in advance

  • What do you guys think to this web site about the health hazards of burning wood:
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