Room Sizing wood burner

[Aitch]

Has anybody got a formula for the size woodburner in a room? Our main room is 6.5m x 5m x 3m, and I have been getiing conflicting advice that I need a 6KW, and up to as much as a 11.5KW woodburner. Would it make any difference that there is a staircase in the middle but to one side of the room?

Thanks

Aitch

[Gluestick]

Makes no difference what appliance or system you use, Aitch.

First calculate the heat loss for the room or area. Then decide what the comfortable ambient temperature you desire is.

Thereafter, input enough heat capacity to heat the room/area to your desired temperature, whilst losing heat at the rate you have calculated.

Simple way to do this is to use a calculator. Quite a few on the web.

Google "Central Heating Calculator". Some are delivered as downloadable freeware software; some are web apps (Web Applications) delivered in real time on screen.

 

[Aitch]

Thanks for that. I'll give it a go

Regards,

Aitch

[Dave&Olive]

hi

     ok you need  1 kw for 14-17 m3  depending on heat loss. got the info from here last friday http://www.woodburner-stoves.com/

              dave

[Aitch]

Dioch yn fawr

Aitch

[shimble]

so if your using an insert with two tubes taking the heat to other rooms in the house do you need to calculate the surface area of all the heated area or will the room with the insert be much hotter than the other rooms with the hot air feeds?

[Anton Redman]

It is not the surface area it is the volume. In general the ducted heat from a wood burner will take the chill off a room it will not heat it. The volumes quoted for wood burning stoves are based on burning well seasoned oak  If you are burning seasoned chestnut or pine the volume heated will be about two thirds quoted in the stove specefication. 

[LesFlamands]

You need to bear in mind that the claimed output is not always accurate. It depends on the manufacturer and who rated the stove. Most manufacturers quote the absolute peak output which has little to do with real life usage. Some manufacturers quote the average output over, usually, four hours on one charge of wood which is much more useful but not always made clear in the spec.. My advice would be to buy a good, controlable stove (Jotul, Villager depending on budget) and make sure that it is slightly oversize for the volume.

[dogwood]

Hi Aitch

 

I cant give you a formula for woodburners, but my main room is the same size as yours.

I have a Supra 11KW woodburner. All I can say is Im glad its no smaller[blink] On some of those realy cold nights during the winter we needed every one of those 11KWs

So I would suggest get the biggest one you can. You dont need to fill it up, but if it is too small you are stuck with it [:-))]

Dogwood

 

 

[Aitch]

We have been looking at the 'Godin' range and the salesman in Chateauroux ,whilst very helpful, perhaps confused the issue by showing us the low and high level of the KW, yet not really explaing the practicalities for what we wanted. My wife wants one of the coloured enamel type as opposed to the black. We have not looked at the others yet. Anybody know of other shops we can visit around the Le Blanc, Chateauroux area?  Back home in the UK we did see the 'Charnwood' and the ''Hunter' ranges. It would appear that the sensible option is to go for the bigger as opposed to the smaller. And yes it does get cold, minus 10, a year last February, and I still don't know the French for 'welding'. However, thanks for all the suggestions and info.

Regards,

Aitch

[shimble]

french for welding is "soudure"

ps this helps lots http://babelfish.altavista.com/tr

[Gluestick]

Aitch, whilst I do agree that specifying anything, slightly larger than calculations dictate is needed is always an excellent concept, I do however advocate that your starting point is a heat calculation.

Manufacturers and of course, salesmen will always quote optimum performance/output, however, this tends to be on the basis that it's downhill with a strong following hurricane!

With a woodburner, so many different variable come into play: as has already been pointed out, different wood fuel produces differing heat values; different levels of dampness, age etc, for identical types of wood, will again affect heat output.

Ducted heat from woodburners is a very variable process: depends on the length of the duct/s, what they go through to reach their destination, what air currents exist in the destination, what the house aire circulation is and so on.

Generally, remember, woodburners are used as boost heat, rather than source heat.

If your locale reaches minus 10 degrees C, then you really need some robust and stable source of core heat, with the woodburner acting as a very pleasant focal point and source of additional/supplementary heating when it's very cold and the core heating, perhaps when not so cold.

Woodburners are not cheap: neither is their professional installation.

Go carefully!

 

[friend of stouby]

There are two points I can add to this thread. We use a 10kW Petit Godin coloured cylinder model, it is a multifuel capable of  burning 50cm pieces of wood and coal/coke. We use it as the sole heating source for 3 smallish interconnecting rooms with the stove in the central room.  The rooms are about 4.5 x 4m each

We have a good installation that works well, ie the stove is very very controllable plus is easy to use. Our min temperatures this winter were around -12 C . The house is not occupied continually, but after we have had the stove alight for 2 days the 50cm stone walls absorb the heat and start to act as storage heaters, and from this point the stove is turned down gradually so that only once a day (first thing in the morning) do we let the stove burn up a little to keep the system clean.

We are burning both seasoned wood (oak and hornbeam depending on what we want from the stove) and coke, again depending on what we want the stove to do. At this time of year with maybe +5 C night time temperatures, the stove is kept alight but now keeps the house too warm during the afternoons. The next stage in our heating plan is to fit a smaller capapcity stove for the spring and autum which will only be lit during the evening as required and use an adapter to connect into the existing flue/chimney set-up.

It all works for us although has taken a winter to work out the small detail for our stove, in our house, with our chimney, in our location, but it isn't rocket science only common sense and instinct whilst bearing in mind safety at all times.

Our stove looks fabulous when lit, and is often worth just sitting in front of to stare at ......

The second point is a friend had a new large house built and enployed a chimney manufacturing company to design and build a chimney sytem for his house. It is a large open fireplace in a very large room. The house had a stair case in a small tower off of this room, with the tower being 1 storey higher than than upper floor. There was no door between the staircase tower and the large living room/kitchen diner.

The open fire would not light or stay alight until by various methods the chimney was heated thoroughly. The outcome was a very powerfull chimney suction fan was fitted to the top of the chimney to create a draught, then the stove stayed alight as it should.

The chimney heating engineers found that the staircase tower was drawing air from the entire ground floor therefore no draught for the fire.

Hope this helps a little and Aitch if you neded more detail just come back to me.

Jamie

 

 

[Aitch]

Thanks to Gluestick and Jamie for the latest advice info.

We won't be at the house all the time, (work is still ongoing with the end in sight, so our visits are between 3-5 times a year) and the minus 10 February visit was more of a one-off as we just wanted a few days away from the UK. Our walls are quite thick so they will retain the heat. The exisitng fireplace and chimney won't, I don't think, give us an updraft problem so the fire will stay alight. Whenever it was occupied before, then it was just an open hearth fire and the soot is enough evidence to suggest everything should be alright (famous last words!!). We have had new wiring complete with electric heater points so that is an option at some time in the future. I will need somebody to come during our next visit to have a good look and see if we can have the vents from the upstairs part of the chimney onto that floor. I take your points about the common sense and safety though.

Thanks

Aitch

[Gluestick]

Interesting point raised by Friend of Stouby AKA, Jamie.

Last year, I replaced the mild steel flue pipe on our woodburner. It is installed in a 200 year old fireplace, which was modified by a galvanised sheet sitting on 90 deg. angle iron, with the flue pipe going up through a hole in the galvanised sheet.

All done by the previous owner.

Chatting about this to my heating engineer chum, whilst we all probably think a flue is a simple matter of conducting fumes away and that's it, this is far from the truth.

Until and unless the flue pipe reaches a minimum working temp and is dry, the correct level of draught will simply not occur.

Further - as Jamie states -  spurious air currents, like up stairwells, can destroy a carefully calculated plan!

At the end of the day, it's all about Heat In : Heat Out, as we have discussed on these boards umpteen times before!

So, a little bit of front end planning, consideration and design, is going to pay a big bonus.

I haven't a clue what the heat output of our woodburner is: all I can say is that it's very big! And eats logs like there is no tomorrow!

Despite this, on its own in Winter, there is no way it could heat our Saloon, which is circa 6.8 X 4.7 metres, on its own. let alone any of the other rooms.