Multi Fuel V Wood Burning Stove

thatsme

We are building an extension and I had my heart set on a free standing woodburning stove. I have now been told by another seller that I would be better off going for a multi fuel stove.

Any one got any advice or experience of either

nophd08

thatsme wrote: »

We are building an extension and I had my heart set on a free standing woodburning stove. I have now been told by another seller that I would be better off going for a multi fuel stove.

Any one got any advice or experience of either

I have just installed a multi fuel but I only burn wood in it. Only difference is the grate, wood burns better on a bed of ash and air from top and coal burns with air from underneath so some of the good multi fuel stoves have an adjustable grate.
I'd go for a multi fuel because then you have the option of burning either, especially if you get a wet delivery of wood.

heinbloed

Nophd08 wrote:

..Only difference is the grate, wood burns better on a bed of ash and air from top and coal burns with air from underneath so some of the good multi fuel stoves have an adjustable grate...

What makes you thinks so, nophd08?

nophd08

heinbloed wrote: »

Nophd08 wrote:



What makes you thinks so, nophd08?

Its what we are reading..
www.whwatstove.co.uk/choosing-a-stove.htm
http://www.hunterstoves.co.uk/FAQs.html

heinbloed

Thanks, nophd08.

The first link didn't work, but in the second I've read:

WOODBURNING
Burn only dry, well seasoned wood. For best results, use dry wood, with a moisture content of less than 20%, which has been cut, split and stacked for at least 12 months. This is advertised as ‘seasoned’ wood. Burning wet or unseasoned wood will create tar deposits in the stove and chimney and won’t produce a satisfactory heat output. Wood burns best on a bed of ash and it is therefore only necessary to remove surplus ash from the stove occasionally.

That it is better to use dry wood is clear to everyone - I hope.
But that

Wood burns best on a bed of ash...

is rubbish.

There might be a translation mistake/error between Danish and English. Ash means the grey stuff, without any carbon left in it. This is the technical meaning of ash.
But in English frequently the term ash is used for the hot, charcoal containing matter. The burning stuff. ("Don't put hot ash into the bin..")

So better ask the heating engineer or the black-smith on how to burn timber: the more surface contact there is between fuel and oxigen the better(the more eficient!) the combustion will be.
A blow bellow will increase the temperature but blow out the ash. Ask the Kelts who invented the metalurgical processes to get the metal out of the ore, they blew air through the kill, no ash was wanted in the fire.
Or ask your boiler suppliers which are the most efficient boilers: the ones without ash in the grit.
Or have a barbecue, but no wet charcoal please.
The presence of ash blocks the transmission of thermal energy, it's quite a good insulator.
And it blocks the combustion, hindering the oxigene reacting with the fuel.
For these reasons a grit is installed in the first place, to separate the fuel from the ash. Allowing the air to supply the fuel with oxigene in an unhindered way to combust efficiently, hot instead of luke warm, glowing instead of smouldering.
Many stoves have a shaker handle connected to the grit, to shake-off the ash from the fuel in case it doesn't drop off on its own.

So clearly that statement is wrong, misleading.

And don't burn wet timber! With or without grit and ash around it: the energy demanded to evaporate the water will be lost with the steam.

Stove Fan

We have a multifuel boiler stove with the grate and find that to burn wood it burns best with the grate removed and let the old wood ashes accumulate to 1 inch thickness:D.
When I have burnt wood only with the coal grate in the log burns well with plenty in but the hot ashes just fall into the ashpan leaving the charred log remaining unburnt. No good for overnight burning:(.

Its the hot ash and having the woods surface area fully exposed to the glowing/hot ash.

Burning wood and smokeless/coal together is inefficient and produces sulfuric acid which is very corrosive to you flue liner/ stove:mad:.

Stoves should not really be advertised as multifuel. A stove with grate fitted is for coal only and no grate is for wood.

If you only ever plan to burn wood buy a dedicated woodburner. Certainly a bit cheaper:)

Stove Fan.:)

heinbloed

Stove Fan wrote:

When I have burnt wood only with the coal grate in the log burns well with plenty in but the hot ashes just fall into the ashpan leaving the charred log remaining unburnt.

This is a typical sign of wet timber being used.

Or a lack of oxigen. But once the stove is hot there should be enough draw to keep the air flowing through, suplying oxigen.
Burning well

with plenty in

could be a sign of to much oxigen, to much air flow as well. The fuel load blocking the air flow to a certain degree and when getting less being consumed the air flow increases, taking away to much heat and cooling the actual fire down to below combustion temperature.
Grandfather's trick was to wrap the logs in newspaper, creating a lot of ash and keep the air flow low in the combustion chamber(see above). But this is energy wasting and air polluting, used with oversized stoves only.
Better reduce the airflow at the air inlet - if there is a reducer/valve!

Try to get dry timber, a few logs 'baked' in the oven for some hours at 110 degrees Celsius. Throw them into the pre-warmed stove overnight and see what remains, if they burn well.

Stove Fan

heinbloed wrote: »

Stove Fan wrote:



This is a typical sign of wet timber being used.

Or a lack of oxigen. But once the stove is hot there should be enough draw to keep the air flowing through, suplying oxigen.
Burning well could be a sign of to much oxigen, to much air flow as well. The fuel load blocking the air flow to a certain degree and when getting less being consumed the air flow increases, taking away to much heat and cooling the actual fire down to below combustion temperature.
Grandfather's trick was to wrap the logs in newspaper, creating a lot of ash and keep the air flow low in the combustion chamber(see above). But this is energy wasting and air polluting, used with oversized stoves only.
Better reduce the airflow at the air inlet - if there is a reducer/valve!

Try to get dry timber, a few logs 'baked' in the oven for some hours at 110 degrees Celsius. Throw them into the pre-warmed stove overnight and see what remains, if they burn well.

No the wood is seasoned 2 year old beech at 15 percent moisture. The problem is trying to burn overnight using the coal grate. What happens is the hot embers don't build up in the grate and fall through the gaps in the grate and so there is less heat to keep the log burning and so it smoulders until it goes out.
It works so much better on the base of the stove as it keeps the log in contact with the hot embers as the hot embers has nowhere to fall to. Grates are for coal as no grate is needed in a woodburner only. Have you tried to burn just wood overnight with the grate in? My stove has primary and secondary air controls to control the burn rate.

Stove Fan.

heinbloed

Have you tried to burn just wood overnight with the grate in? My stove has .....

Yes, perfect.

Again: try to use dry timber, use the drying method described above. Timber at 15% moisture - stored in Ireland outside - isn't available in winter.
If you keep logs outside the moisture content in our climate will be (during the winter time ) at least 18%, propably well above 20%.

The min. drying time for logs is 3 years, as a rule of thumb: 1 year per inch of diameter. Covered against rain and snow at all times, protected against driving rain. But well aerated at all times as well.

Logs aren't a good choice when going for space heating in our climate. Using seasoned twigs and branches for cooking and preparation of DHW in Summer or Autum is a different issue, these would indeed go down to 15%. If the summer is dry.

An alternative would be to store the logs in a heated and dry room, this would eliminate the climate caused re-moisturing of timber during the cold season of the year.

Remember that the anual average air moisture is well above 80%, in winter propably (depending where you live) around 90-95%. Check the Met Eireann home page for your region. So there is no chance of timber stored outside in Ireland to go below 15-18%, depending when you meassure it, Summer or Winter.

Ask at your local timber yard why they cover their kiln dried timber. Building rules/regulations demand a max. moisture content of 18% for loadbearing timber. It would be unsellable if it wasn't dried artificially AND stacked under cover.

That's our climate, not the fault of the stove (smiley).

Stove Fan

heinbloed wrote: »

Yes, perfect.

Again: try to use dry timber, use the drying method described above. Timber at 15% moisture - stored in Ireland outside - isn't available in winter.
If you keep logs outside the moisture content in our climate will be (during the winter time ) at least 18%, propably well above 20%.

The min. drying time for logs is 3 years, as a rule of thumb: 1 year per inch of diameter. Covered against rain and snow at all times, protected against driving rain. But well aerated at all times as well.

Logs aren't a good choice when going for space heating in our climate. Using seasoned twigs and branches for cooking and preparation of DHW in Summer or Autum is a different issue, these would indeed go down to 15%. If the summer is dry.

An alternative would be to store the logs in a heated and dry room, this would eliminate the climate caused re-moisturing of timber during the cold season of the year.

Remember that the anual average air moisture is well above 80%, in winter propably (depending where you live) around 90-95%. Check the Met Eireann home page for your region. So there is no chance of timber stored outside in Ireland to go below 15-18%, depending when you meassure it, Summer or Winter.

Ask at your local timber yard why they cover their kiln dried timber. Building rules/regulations demand a max. moisture content of 18% for loadbearing timber. It would be unsellable if it wasn't dried artificially AND stacked under cover.

That's our climate, not the fault of the stove (smiley).

We store our firewood in the garage with good ventilation.

We are going to use only wood to run our heating system this winter. It heated the 5 rads and hot water surprisingly well last winter when we used up 4.5 cubic metres of pine. We then fitted the grate and burnt just coal but it's very dirty. Wood is much better although dearer:(.
I can't believe most dealers are asking 60 euro + a cubic metre for pine and think 1 year of seasoning is enough. When we lived in Northern France spruce was 20 euro a cubic metre cut and delivered and 3 years old and very dry. Oak was 50 euro. Saying that though coal was extortinate. Coal is cheap here.
Ash is my favourite wood. Very low water content:D

Stove Fan:)

nophd08

Now I'm confused, Are some woodburning stoves sold with just a flat plate or pan and no grate.?
http://www.stovesonline.co.uk/woodburning_stove.html


Woodburners
A woodburner, (or wood burning stove), has a flat bottom on which the wood burns on a bed of wood ash. Wood certainly burns slowly better in a woodburning stove than in a multifuel stove, so in this sense a woodburner is better suited to burning wood (as the name "woodburner" would suggest).

Stove Fan

nophd08 wrote: »

Now I'm confused, Are some woodburning stoves sold with just a flat plate or pan and no grate.?
http://www.stovesonline.co.uk/woodburning_stove.html


Woodburners
A woodburner, (or wood burning stove), has a flat bottom on which the wood burns on a bed of wood ash. Wood certainly burns slowly better in a woodburning stove than in a multifuel stove, so in this sense a woodburner is better suited to burning wood (as the name "woodburner" would suggest).

Yes, a woodburner is suited to burn just wood/peat and you just burn the wood on the base of the stove. Usually the base is lined with firebrick and in most the sides are lined too.
With a woodburner you have more room to load wood as you don't have the grate and ashpan taking up room. Makes ideal sense for wood only. We had a villager A range woodburner boiler stove (AHI) but for 115 pounds more you could buy an optional grate to burn coal. We bought the grate just in case we ran out of wood but never did.

Some use steel liners to act as firebricks, although I'm not a fan as the replacements can be very expensive.
Most stove manufactures give you the optional extra of a grate to convert your woodburner to burn coal.
Some manufacturers give you the option of a steel plate to place over the grate to convert it to woodburning only and some stoves manufacturers grates are able to convert to coal use or woodburning with like a lever on the side.

If you buy a hunter or villager stove buy the optional flue damper.

What stove have you in mind?

Stove Fan.

nophd08

Stove Fan wrote: »

Yes, a woodburner is suited to burn just wood/peat and you just burn the wood on the base of the stove. Usually the base is lined with firebrick and in most the sides are lined too.
With a woodburner you have more room to load wood as you don't have the grate and ashpan taking up room. Makes ideal sense for wood only. We had a villager A range woodburner boiler stove (AHI) but for 115 pounds more you could buy an optional grate to burn coal. We bought the grate just in case we ran out of wood but never did.

Some use steel liners to act as firebricks, although I'm not a fan as the replacements can be very expensive.
Most stove manufactures give you the optional extra of a grate to convert your woodburner to burn coal.
Some manufacturers give you the option of a steel plate to place over the grate to convert it to woodburning only and some stoves manufacturers grates are able to convert to coal use or woodburning with like a lever on the side.

If you buy a hunter or villager stove buy the optional flue damper.

What stove have you in mind?

Stove Fan.

I'm already up and running, I was just confused with heinbloeds posts. I have installed a Hunter multifuel 5kw which funny enough, when burning wood,and a bed of ASH has built up and close off air from underneath and open airwash "air from top", it burns beautifully. Strange Physics??? All stove manufacturers cant be wrong. Even guys who are building shed heaters from old gas cylinders are including top air intakes.

DDen

Considering a Hunter Kestrel 5 stove as it fits in front of my open fireplace.Can't find any customer reviews for it on line. What does the optional flue damper mean?

Stove Fan

DDen wrote: »

Considering a Hunter Kestrel 5 stove as it fits in front of my open fireplace.Can't find any customer reviews for it on line. What does the optional flue damper mean?

This site lists hunter 5 but not kestrel:)
http://www.whatstove.co.uk/reviews/stoves/stove-reviews/_c33/

A flue damper controls the rate of burn. It opens or reduces the passage of draught (Draw) up the flue. It's very usefull for overnight burning or controlling the fire if it's very windy. Or if your stove lets air in around the door(s) and it's burning too much closed up you can close up the damper to give a 2nd level of control. On most stoves you pay extra for a flue damper.

On very good quality stoves like clearview you don't need a damper as they are far more airtight than the lesser priced stoves.

Stove Fan:)

marcoz

Hi all,
I have a query. Im doing a new house build and I had more or less pulled the trigger on a multifuel stove, I came across it at a self build show and got a great price and the efficiency was up at 79 or 80%, how just as I started to get to the nitty gritty BER details, I was advised by my BER consultant that the stove had to be certified for wood only. If the stove mentions at all about multi fuel or solid fuels other than wood, then it cant be used to contribute to the Part L BER compliance regs. He is in fact on the ball as he then sent me on the regs on this. So now Im on the hunt for a wood burning only stove WITH paper documentation to state its only wood burning and tested with wood only BUT I also have to have external air option on it as the house has a considerable air tightness(not a passive house) factor on it. it has to be around 5 kw. Anyone got any suggestions here on a stove that fits above options that wont break bank. I was hoping it could be a bit more modern, not really traditional but not a real contemporary one like some of the Scandanavinan models. Oh and its in a chimney breast but will be free standing. Not a stand alone stoe that is a feature in the room in itself. Seen a nice Irish one called the Heritage Dunkerron 7kw but I cant get any paperwork anywhere on it.

Any help at all would be great

Thanks in advance