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Author Topic: log biomass how big  (Read 3878 times)
coldair
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« on: February 05, 2012, 10:45:49 PM »

Been looking the internet for week or 2 & stumbled across this site to-day quite impressed about all the info on here.

Anyway my house, stone built cottage 200m2 floor space 300m3 to celing loft insulated walls not very well old lathen plaster on most of it. Aberdeenshire so can be winter for  8 month spring 7 weeks away on holiday for 2 autum 7 weeks then back to winter

Current system 60000 btu oil boiler which can heat the house not too bad  & 14kw log boiler stove which heats the living room & takes the chill off the rest of the house also both systems heat the DWS

Have been looking at 40 kw log biomass 91% effective with 2000ltr accumulator mabe this is a little big but always better to have spare

Sort of decided today that i would be better placeing the boiler & tank in a shed of its own rather than in the garage thought it could be a wee bit messy

Currently burning around 12 - 15 ton per year around the same as a 60 kw system i seen this week

Any advise welcome
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dhaslam
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« Reply #1 on: February 05, 2012, 11:36:40 PM »

You do need to  take manufacturers figures with a pinch of salt.   In theory a 40 kW boiler will use ten kilos of dry wood  per hour and heat the 2000 litre store  by about 16C per hour, in practice it may not quite do that.  However  even if it needs to run for ten hours daily you should get away with   about twentyfive tonnes per annum plus what you need to keep the other stove running when needed.   Anyway it should be  a big saving on oil. 

You are already using a lot of wood so  you are used to it.    It is important to have a good amount of storage in the boiler room so that you can  fill the stove easily at night  or on wet days and  to give extra drying to the wood.   It needs to be in a few sections so that you can empty one section at a time for refilling and set it up that you can  throw the wood  in easily.   You  may need to add extra insulation to the store, otherwise it might lose too much temperature that either leaves DHW too cold or  needs  heating to too high temperatures, as well as heat loss of course.       
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DHW 250 litre cylinder  60 X 47mm tubes
Heating  180,000 litre straw insulated seasonal store, 90X58mm tubes + 7 sqm flat collectors, 1 kW VAWT, 3 kW heatpump plus Walltherm gasifying stove
Bodidly
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« Reply #2 on: February 06, 2012, 07:42:19 AM »

Welcome coldair

12-15 tons is  a lot of wood!
Is it possible to improve your insulation, I know it's not much fun but it can save you a fortune in the long run.

Beau
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Mike McMillan
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« Reply #3 on: February 06, 2012, 08:05:21 AM »

We are heating a 7 room 1860's house with a 40 kw wood gasification boiler.The 2000 litre storage tank and boiler are 35 meters from the house. Working brilliantly, 2 wheel  barrow loads of wood, normal winter (down here), 3 when it got really cold (-5) last week. I estimate about 6-8 tons of wood a year, (being frugal).

Mike McMillan   I.O.W.
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Off grid; 4KWH install charging Rolls 24v 1000 A.H. batteries with 3 Tristar controllers. 3KW Victron Inverter with FIT meter on output. Relay driver automatically opens circuits as battery charges. 6 x 15 experimental solar collectors feeding 250 L. tank.  Angus wood gasification boiler.
renewablejohn
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« Reply #4 on: February 06, 2012, 08:26:26 AM »

Coldair

I live in a draughty old farmhouse heated totally by wood and would find it difficult to use 5 tonne in a year never mind 15 tonne. You say you have insulated the loft but how thick is the insulation. In our farmhouse we have 600mm in total. 200mm in rafters 200mm between ceiling joists and then 200mm laid across ceiling joists. This would be the minimum  I would need in my loft before I looked at changing heating systems. Unfortunately I cannot do much about the stone walls which are 2ft thick as it is a listed building although we will be changing the windows from single glaze to triple glaze which should stop some of the draughts. I am currently looking to reduce the amount of timber used to heat the house and hot water by installing a rocket stove heating system.
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coldair
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« Reply #5 on: February 06, 2012, 08:37:08 PM »

Thanks for the replies
I have about 270mm isulation in loft which i thought was working well as it is allways very cold up there at this time of year.      I think most of the heat loss is through the walls where there is very little insulation if any + i dont think it would be too good an idea to fill the back of the walls with insulation as there is a tendency for damp which probably wont dry off if there is no air in there.

just 1 more thing the stove & boiler that i work at the moment are connected to a equilizer tank about 500mm diameter 200mm deep which then feeds the DHW tank & radiators circut  would i just tee new system in to the same tank direct from the accumulator
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Bodidly
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« Reply #6 on: February 06, 2012, 08:52:39 PM »

"i dont think it would be too good an idea to fill the back of the walls with insulation as there is a tendency for damp which probably wont dry off if there is no air in there."
Often the damp is not moisture coming through the wall but condensation forming on it because it is cold.
It is possible to insulate most walls either on the inside or the outside. I have done both but I have to admit it is not always easy.

Beau
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Solal
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« Reply #7 on: February 08, 2012, 11:31:00 PM »

Had you  considered a multi fuel  fan assisted  solid fuel boiler?  And no  expensive accumulation  tank  taking up space.
And connect direct  to the heating system. Upsize  the hw storage cylinder  for extra  capacity  only.
A lot cheaper  install  and works fine.
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chasfromnorfolk
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« Reply #8 on: February 09, 2012, 09:30:17 AM »

Had you  considered a multi fuel  fan assisted  solid fuel boiler?  And no  expensive accumulation  tank  taking up space.
And connect direct  to the heating system. Upsize  the hw storage cylinder  for extra  capacity  only.
A lot cheaper  install  and works fine.

As I'm in a similar situation to Coldair and would like to follow any solution found here, what are the choices in "multi fuel  fan assisted  solid fuel boilers" and would they qualify as "biomass" in the eagerly awaited Green Deal?

Chas
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Brandon
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« Reply #9 on: February 09, 2012, 10:59:39 PM »

Coldair,

May I suggest that you contact lightfoot, he ought to be able to sort you out, and is relatively local.
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changing the world, one roof at a time.

Quality is never an accident; It is always the result of
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skilful execution; It represents the wise choice of many
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Solal
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« Reply #10 on: February 09, 2012, 11:15:59 PM »

Had you  considered a multi fuel  fan assisted  solid fuel boiler?  And no  expensive accumulation  tank  taking up space.
And connect direct  to the heating system. Upsize  the hw storage cylinder  for extra  capacity  only.
A lot cheaper  install  and works fine.

As I'm in a similar situation to Coldair and would like to follow any solution found here, what are the choices in "multi fuel  fan assisted  solid fuel boilers" and would they qualify as "biomass" in the eagerly awaited Green Deal?

Chas

Something like  the WB  or WBI series.
Kotly  have them priced very  keenly. Have  fitted a 40kw  ksw-ksw model  in a property about 18 months ago  and the oil  boiler    is rarely used now.
There are other makes  also.
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Stuart
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« Reply #11 on: February 10, 2012, 08:05:07 AM »

+1  lightfoot, he's you man
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8kw woodburner, Big piles of wood, 20 tube solar panel, custom tanks, back up gas boiler, North walls internally insulated
1968 landy that runs on anything and a currently wild meadow garden.

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