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  • 26-07-2009 11:05pm
    Registered Users Posts: 23

    hELLO ,

    Im looking for information on wood chip boiler for heating detached

    2500sqft cavity block house .

    What size wc boiler would work with this size house , or would oil/gas condensing burner with solar heat be a better heating system ?

    I am intersted in this as i have a ready supply of ash thinnings i could chip and i have space for storage .

    Anybody any experience of using wc burner for central heating and dhw ?

    All Replies greatly appreciated



  • Registered Users Posts: 648 ✭✭✭PeteHeat


    There are good wood chip systems available however they are usually used in larger commercial buildings mainly due to the cost of good technology.

    Moisture content plays a big part in the efficiency of all types of wood burning boilers so on site chipping may not provide you with good quality fuel.

    The level of insulation (energy efficiency) along with heat loss calculations of your build will establish the size of boiler needed, there are professionals on the BER forum who can carry out the calculations for you.

    Depending on the amount of time you have to put into preparing the fuel, (cutting drying etc) you might want to look at a wood gasifier, if time is a problem pellet is easier to automate.

    Oil is rising in price again so the chances are you may be back looking for an alternative source of heating in the near future, solar is always a good combination with either technology.


  • Registered Users Posts: 424 ✭✭Cuauhtemoc

    Hi gerzilla,

    Have recently bought a 25Kw Eta hack woodchip boiler.
    Google it and you'll find the main supplier or you'll probably get a pm from a certain member in here :)
    25kw Is more than sufficient for our purposes but gives us room to expand the house in the future. There isn't much difference in the boiler price from 20Kw up to 35 or maybe 40kw i think.
    The Eta is quite dear but found it to be far more efficient than either of the other two main brands that took woodchip(that also qualified for a grant). The Baxi MultiHeat and the Benekov Prime.

    It uses far less electricity(a consideration over the lifetime of the boiler) and is up to 94% efficient compared to somewhere between 88 and 91 for the other two. I'd have to double check those figues, i posted them here somewhere before,but they're not far off.

    Hope that's of some help.

    Edit...found post from last year...some info may have changed since then of course...

    01 July last year...
    Am looking at woodchip myself as it suits our site. Lots of dead wood and will grow some coppiced willow to supplement(several people have said it won't pay but plan to try it anyway) Suppose we could also go wood gasification as well which is very good.

    Why specifically woodchip btw?
    I went that route for greater flexibility to wood pellet.

    Anyway 3 main boilers i'd narrowed it down which all seem very good were

    Baxi multiheat 2,5
    Fuel: Woodchip setup(It can also be configured for pellets/grain/corn). Chips upto 25% moisture content.
    Efficiency: is 89-91%.
    Output: The smallest baxi that will burn chips is 25kw
    Electrical Consumption: max 460w(less for pellets)

    The Benekov prime 27 biomass boiler.
    Fuel: Will burn pretty much anything from chips(no idea of max moisture content) grain corn and logs(up to 12hours i think) up to 40cm.
    Output: 25kw.
    Efficiency: Not sure of efficiency but the 15kw is 91.3% but the 25kw is not listed.
    Electrical consumption: max 230w (less for pellets)

    The Eta Hack.
    Fuel: Will burn Chips(up to 35% moisture content), grain, corn, pellets, sawdust even(may be useful for those with pellet troubles??). The other two may but i haven't seen it in the literature.
    Output: This comes in 20kw and 25kw or higher if needed.
    Efficiency: Approaches 94% efficiency with pellets and 93% with chips.
    Electrical consumption: max 147w. less for pellets.

    I had decided on the Eta as i felt it was the best(could well be wrong) The heat exchanger only needs annual cleaning. Can't remember the ash tray off hand. Approaches 94% efficiency with pellets and 93% with chips. Will even handle nails in the wood into ash tray.
    My only sticking point is cost atm

    Fully commissioned the Eta is about 15k, if you get the grant.
    I'm in the process of getting Fully commissioned prices for the other two but i think may be around 10k. Big difference.

    Some links for the boilers (click on the english flag)
    The benekov site is in Czech only. But there are a couple of Irish suppliers you can google.

    Hope this is some help.



  • Registered Users Posts: 23 gerzilla


    cheers for the Info on wc burners ,

    How is it working out for you since installation.
    What kind of moisture percentage are your chips ? or does it burn ok with mixed moisture levels (-dry mixed with 30-40% moisture wc)
    What size house are you heating ? Does it work well with ufh .
    Does the conveyor system work well .
    What do you get for 15k. accumulator tank etc

    Pete heat

    I do need to get my calculations right for the size of boiler needed .. (looking at b1/b2 ber class -2500sqft)
    The wood gasification boiler could b an option with solar .. only disadvantage is having to keep it burning and fueled manually.