# Wood Gasification Boiler



## Brave Inca (27 Apr 2009)

Hi,

I would welcome any comments/thoughts on which the better heating option for new build:

1.wood gasification boiler
2.geothermal

Rgds
Brave Inca


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## thlint (2 May 2009)

I use a log burning boiler frohling 30kw. Burns very well and very little ash. Requires a lot of work cutting chopping etc. 
I use it with an oil boiler back up for when i am lazy.
Wood chip  pellet would be more automated.


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## alexchediak (5 May 2009)

Brave Inca said:


> Hi,
> 
> I would welcome any comments/thoughts on which the better heating option for new build:
> 
> ...


Geothermal Energy Systems have harnessed that power to supply a clean 
 renewable source of heating to your home.                       Deep under the earth’s surface, 
                     water comes into contact with hot rock and turns it into boiling hot water or steam.

On top of 70% lower heating bills Geothermal heat pumpshttp://www.techstore.ie/Renewable-Energy/Geothermal-Energy-Systems/Geothermal-Heat-Pumps.htm have the following advantages:

 • High reliability and longevity (on average lasting over 20 years)
 • Little or no on-going maintenance (no boiler cleaning, no chimney sweeping, etc.)
 • The healthiness and comfort of low temperature heating systems
 • A real contribution to a better environment


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## Superman (5 May 2009)

alexchediak said:


> Geothermal Energy Systems have harnessed that power to supply a clean  renewable source of heating to your home.



I suspect she means a standard ground source heat pump - and not a true "geo-thermal" system.


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## ninsaga (5 May 2009)

alexchediak said:


> Geothermal Energy Systems have harnessed that power to supply a clean
> renewable source of heating to your home.                       Deep under the earth’s surface,
> water comes into contact with hot rock and turns it into boiling hot water or steam.
> 
> ...



very sales like there alex - do you sell these?


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## superderm (13 May 2009)

I'm planning to build a house next year and I am giving Geothermal alot of consideration. There are so many systems out there so I am starting to investigate it now.The option of wood is nice but as thlint says there is a bit of work involved. I think I will probably have a fireplace for burning wood and supplementing the Geothermal. 

I understand that Geothermal is hard on Electricity,anyone any thoughts on that?


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## villa 1 (13 May 2009)

I'd go for a ground source heat pump that has a proven high COP(Coefficient of performance) eg: A heat pump with a COP of 4:1 will give out approx 4kilowatts of heat for 1 kilowatt of electric power consumed. 
The higher the operating temperatures  on the heating system side of the heat pump the lower the COP = Higher electric consumption, more cost. If you install a heat pump use underfloor heating throughout your build (buffer tank) and supplement your domestic hot water heating with electric immersion/solar panels.
Do your ground work and talk to people who have installed heat pumps and see how happy they are with them. A Heat pump installation is a very expensive option in a new build in comparison to a condensing oil/gas and solar panel installation.
I have heard of many people who have been very dissapointed with heat pumps that just don't deliver on heat. Be carefull to employ a qualfied plumber who has a proven track record in heat pump installations, as there are chancers out there who have jumped on the green bandwagon!!


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## thlint (14 May 2009)

Getting back to the gasification.
The wood gasification means that the fire in the boiler does not come in direct contact with the water instead it is the hot exhaust fumes that heat the water. The exhaust goes into a ceramic chamber that gets very hot and re burns the fumes from the fire hence the name gasification.
This means that the fire burns very hot and efficient. With my type of boiler the burn (flame) is downwards so that by the time the wood drops to the burn area it is dried. You can burn fairly fresh wood if necessary. It will burn almost anything it is more of an incinerator than a boiler ( dead hens etc)
Only choose a log burning boiler if you have a supply of wood. You need about 4-5kg wood for every Kw. This means 3-5 tonnes for every 1000lt of oil. The same applies to chips and pellets hence you require large storage area.
Overall this boiler paid for itself within 3 years in oil saved.


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## irash (14 May 2009)

Thlint,
Could you possibly say how much wood is needed per day to heat an average 3bed semi (100 sq.m.) (winter time)?


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## thlint (15 May 2009)

It is hard to say . I am heating about 350m with multiple  zones. The amount of wood depends on the kilowatt demand in the house the quality and dryness of the wood. I would think that about 3-4 wheel barrow loads. 
You really need a buffer tank  to cope with extreme variations in demand. normally the burner is filled and burns at full output any excess heat produced over demand is stored in the buffer tank to be used later. A full burn lasts about 4 - 6 hours.
I found that the low return temperature of the underfloor system puts the boiler under pressure esp if the underfloor has been allowed to cool down.
I can say that the amount of wood used is shocking. I now look at trees in terms of time it would take to burn. I require about 3-4 large trees per year. A log burner helps you realise just how much energy is required to heat a house.
Although not for everybody there is a certain pleasure in chopping and burning wood.


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## Mercantilist (15 May 2009)

irash said:


> Thlint,
> Could you possibly say how much wood is needed per day to heat an average 3bed semi (100 sq.m.) (winter time)?


Im using 30kg of wood per day to heat a similar area, plus the hot water tank. Thats about one and a half wheelbarrow loads per day. That is a hell of a lot of wood, which requires a place to store it. The wood must be stored for a few months after chopping, so it can dry out. So you need a lot of shed space.

Personally I cant see how youre going to have enough space for a wood boiler in a 3 bed semi.


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## RVR (15 May 2009)

> The amount of wood depends on the kilowatt demand in the house the quality and dryness of the wood.


Thlint is correct - the more moisture in the wood the more energy is lost when burning it.  This is because it takes energy to evaporate the moisture.

For example:



 1 cubic metre of wood with 18% moisture will release about 1961kW of energy when burned.
 1 cubic metre of wood with 35% moisture will release about 1875kW of energy when burned.
 
At around 90% moisture the energy released will be nil.  This is a rough estimate and varies with the type of wood.  

In practical terms however:



 0.1 cubic metres of wood at ~18% moisture in a 33kW boiler provides between 100-115kW over 3-3.5 hours of burning
 0.1 cubic metres of wood at ~35% moisture in a 33kW boiler provides between 95-110kW over 3-3.5 hours of burning.  It could potentially be even less if not lit properly.
 
This energy needs to be buffered in a large tank (1500 litres or more for a 30kW boiler) and can then be used to heat zones, dhw etc as normal throughout the day.

You will have to look at your heat loss on the coldest day of winter to figure out exactly how much wood you would need to burn to heat the house but this should give you some idea. 

With the boiler above, a house with 90kW of requirement would get by on 1 load a day in winter and less during the rest of the year.


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## irash (17 May 2009)

Thank you very much for such comprehensive explanation. It does seem to be a hell of a lot of wood...
Sorry if this is a completly dumb question, but how many times a day do you have to put more logs in to the burner? Is one really tied up to that boiler, or you just load it up, say twice a day?
Txs


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## JoeB (17 May 2009)

deleted, error made.


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## RVR (18 May 2009)

irash said:


> Is one really tied up to that boiler, or you just load it up, say twice a day?
> Txs



Once you load the boiler and set it burning you leave it alone until it finishes.  If you need two loads to heat your house, then you just do this twice throughout the day etc!

Cheers

Des


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## YDB (22 May 2009)

Spend your money on proper insulation and air tightness to your new home and reap the rewards with a smaller heating requirement. I have heard of many horror stories WRT geothermal and believe that the quality of workmanship in installing adequate floor insulation may be the reason it fails in some installations as it ends up heating the ground!


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## killenagh (27 May 2009)

thlint said:


> I use a log burning boiler frohling 30kw. Burns very well and very little ash. Requires a lot of work cutting chopping etc.
> I use it with an oil boiler back up for when i am lazy.
> Wood chip pellet would be more automated.


 
Hi thlint,

That seems an interesting option. 

I am now down to the decision making terratory on this area of the build.

Did you go the supply and install route?
Did the same people fit the oil boiler back up?
Can you give me an estimate of the cost for each of the systems?
Is it possible to let me know who supplied and installed the systems?

Any help would be appreciated, thanks.


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## thlint (31 Aug 2009)

Sorry for delay in replying
Oil boiler was in building before I moved in. Wood boiler and controls were installed by powertech (supply and fix) Omagh. Note the frohling wood boiler is loaded with controls(computerised) to control when the oil burner operates based on water temperature, time . It could also run the various zones but this was already taken care by a valves and timers with thermostats. Buffer tank (euro 1,000) essential with wood boiler  (euro 4,000) controls ( Euro 2,000) + fitting and pipes.


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## Peter C (6 Sep 2009)

Gasifier  is not really suited to 3 bed semi as most don't have the room to store the timber whether it's bought in dry (less than 20% mointure) or chopped and allowed to dry, even the smallest gasifier needs a buffer.

Geothermal, first have your site tested to make sure it is suitable for a ground collector, anyone who tries to sell you a heat pump without asking about your site give them there walking papers !
Works well when sized correctly to under floor heating and a house built with high insulation levels, however good heating controls are vital, make sure your plumber, electrician and supplier work well together.


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## dits123 (3 Nov 2009)

hi can you tell me what is the boiler make you are using?


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## galwaytt (3 Nov 2009)

YDB said:


> Spend your money on proper insulation and air tightness to your new home and reap the rewards with a smaller heating requirement. I have heard of many horror stories WRT geothermal and believe that the quality of workmanship in installing adequate floor insulation may be the reason it fails in some installations as it ends up heating the ground!


 
This is the best advice, really, as, the better you build your house, the less sensitive, or critical, your choice of heating system.  And, the more expensive/complex it is, the payback time gets much, much longer.

Remember, reducing your monthly fuel bill, but having a bigger mortgage for a more expensive system, may be a false economy......


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## thlint (4 Nov 2009)

For dits123 
The wood burning boiler i have is 
Frohling FHG turbo 3000.   Log burning gasification 30kw boiler


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