Tar in your flue

[Alycidon]

Been reading another thread about how long you lads keep your stoves running by shutting them right down.

 

When you shut a stove down you are telling it to release heat that would usually be released over an hour to so to release that heat over say 9 hours. As a result the temperature within the stove drops significantly.

 

Now most if not all wood contains creosote, this is given off in gas form and is normally combusted in the firebox where it makes a good contribution to the heat output. However if the temperature within the firebox drops below the combustion point of the creosote it wont burn but instead gets up into the chimney where it condenses and liner the chimney with tar. At some point it is then possible that you may have a chimney fire.

 

So my question to those of you with non defra stoves who burn wood on log overnight burns, do you get any tar in the chimney?. Be surprised if not but if not what woods are you burning to achieve this. ( Defra stoves are usually set up in such a way to prevent the operator from shutting them right down, thats when pollution occurs).

 

The other issue is that shutting the stove down reduces the air flow across the inside of the door leading to claggy glass next day, the new fire will burn that off but it will take a while.

 

Personally in my 8kw stove I load big lumps of Ash at 10.30pm and shut it down by about 20%, any more and its dirty glass. At 6am my stove is no more than warm. For extra heat I pop a few handfuls of smokeless coal into the back corners, stove is then to hot to touch at 6am and raking those coals into the centre of the firebox restarts the fire when kindling is added.

 

I do have customers with Esse Ironhearts with the wood box option, you can load a lot of wood in that, users tell me that they burn overnight easily.

 

Customers with 5kw stoves have to use smokeless fuel or smokeless coal for long burns. I have several 5kw stoves that I have sold that run 24-7 from Sept through to May on smokeless.

 

So anyone have tar issues?.

A

[Jesse]

OK, not wishing to get too technical now, the best and most efficient way to maintain through air flow and combustion and to minimize residual combustible buildup (Tar) from within a standard 225mm internal flue lining (Clay pipe lining) is best achieved by a steady evening burn of ones arizings , this method also contributes greatly to the green ethos to which we are as citizens of this great country and Beings of planet Earth are duty bound and inspired to do so, the way in which we conduct our self's should be considered when carrying out this act, it should not be done without appreciation of the act, as you open the stove door and throw in your EMPTY Can of Beer, or Can of Coke you will be treating you flue and the environment and most importantly of all your self to trouble free running of your stove, once a year sweep the flue and you will be very surprised at how little residue falls out. You will of also enjoyed yourself. I'v just been cleaning my flue

[Woodworks]

When it gets cold we will keep our stove running continually. It does not have the best seals so not much left to relight in the morning then give it a good blast for a bit to clean things out. Get a handful of soot once a year when sweeping. Insulated flue in room so probably stays warmer than most so very little condensing of creosote. Wood burned is ash,beech sycamore at around 20-25% (soggy part of the world)

[difflock]

A 9" clay lined vermiculate insulated 2 storey flue.

Since 1996 we have run the Morso 6 months of the year.

First 7 or 8 years 24/7 on Birch, heavy lump in last thing, and spin the knobs shut.

rekindle from the embers in the morning.

Occassional controlled chimney burn.

Latter years running on Conifer, no point in even attempting to "overnight"

but still burning daylight hours for 6 months of the year.

No chimney fires of any sort.

And/but

Chimney never been cleaned in its 17 year life and still pulls like a train.

marcus

[Buzzsurgeon]

I run my stove 24hrs in the winter, loading it up before bed and shutting down to a slumber. I burn all sorts green ash and semi seasoned stuff. The stove is fairly big and can take a 22" log.

I sweep chimney every couple years and around half a bucket of soot comes out. I use a SS flexible liner, never had a problem in last 10 years.

[predator]

i leave my coalbrookdale severn to slumber overnight glass is black but not bothered etc as i have a temp clock the ones you hang inside your oven been running three years and no flue pipe i get about 3/4 of a henry hoover full of ash from the top register plate i just stick my digi camera up there once a year etc no worries so far and house is almost 100 y/o and always had a fire of some sort and all my overnight wood is mainly sycamore ash beach but run a mix softwood coni pop and some sycamore during the day

[woody3]

daytime use softwood joinery offcuts, overnight 8x2 inch c24 1 foot long, no tar problems. never open fire up except for lighting

[essential]

Put my stove in2 years ago (morso squirrel) I have it burning constant throughout winter, fill her up of an evening, then a rake of the embers in the morning and of she goes. I didn't get it swept the first year then just as we were coming to the end of the second season the stove stopped drawing and was just filling the room up with smoke.when I got the chimmney sweep out, he had to force the brush out the top he said it was virtually blocked up there.ive only been burning ash and beech, but I suppose closing it right up at night just doesn't burn efficiently enough and you really tar up the chimmney.

[openspaceman]

Put my stove in2 years ago (morso squirrel) I have it burning constant throughout winter, fill her up of an evening, then a rake of the embers in the morning and of she goes. I didn't get it swept the first year then just as we were coming to the end of the second season the stove stopped drawing and was just filling the room up with smoke.when I got the chimmney sweep out, he had to force the brush out the top he said it was virtually blocked up there.ive only been burning ash and beech, but I suppose closing it right up at night just doesn't burn efficiently enough and you really tar up the chimmney.

 

Apart from chimney fires this is the real danger of soot and tar restricting the flue. You will notice if the room fills up with smoke because the acrid smell may wake you up but if you have just the char embers burning in the reduced oxygen of the firebox then it's carbon monoxide that seeps into the room, odourless.

 

I have a picture somewhere of a gas termination cowl almost completely blocked by soot where a pellet boiler had been fitted.

 

For this reason alone it's good practice to sweep the chimney, although I tend to do mine every 2 years as I need to take the Jotul out of its alcove. I'd brefer to do as Fred Dibnah and sweep from the top...

 

What one needs to consider is that wood burns as offgas, from pyrolysis products, and char. The offgas can only burn as a flame (by definition) and it's over 50% of the calorific value of the wood, so a smouldering fire is wasting half the energy in the wood as well as depositing PICs, CO, methane and other polutants into the atmosphere. It's burning char that powers the process.

[woody3]

fit a carbon monoxide detector