Log burner

[Marco]

Logs? We have them delivered! Seasoned hardwood ones in massive 'barrow sacks', which I stack in our wood store. Bugger having to look for or chop wood... It takes me long enough to clear out and clean the wood burner every day, as we burn logs and (smokeless) coal, as I hate it looking messy!

Marco.

 

[35451]

Been running a Jotul F250 3-9kw for 13s year that we originally bought second hand. Still on original glass (cleaned with wood ash and old cloth), rope seals replaced, swept once a year, and never a had problem.

We now only burn low moisture kiln dried ash and oak - having been through most other variants of softwood, seasoned hardwood, joiners offcuts, heatlogs, smokeless coal - finding it to be best blend of cost vs heat vs cleanliness and low ash.

My view is that a slow burn is a good burn. I do leave it in all night when its really cold and it does keep downstairs tickover warm. Once stove is warm, its simple to stack it full, damp it right down, and let the logs effectively turn to charcoal, at which point they really start to glow crank out the heat. This keeps glass clean too.

I regulate the heat output by changing fuel levels laoded within rather than opening top or bottom vents, which i mainly use for lighting or when it has died down too much. Keeping good bed of warm ash is key.

It's a doddle to light, and with the right wood, a joy to run.

 

[Tigerjones]

Running a fire as above is an inefficient use of the wood. Without a decent amount of air you aren’t getting secondary combustion and are effectively only getting a low percentage of the woods potential heat output.

Also, what’s the point of heating a room downstairs when you’re upstairs in bed?

 

[bob atherton]

We’ve had downdraft issues, for us it’s on days with no wind. Leaving door of stove open when not being used seems to get air flow going up. Otherwise use a blowtorch!

We have two Chesney wood burning stoves and if there is a downdraft before I light them I open a window and this seems to balance the downdraft. I then close the window when the stove pipe has warmed. Works every time, though it took me a while to work this out.

 

[mandryka]

It happens sometimes because there's a column of cold air in the chimney. The cold air is heavier than the hot gasses from the fire, and they just can't get past it.

The old fashioned way, and it works, is to burn newspaper sheets one by one -- paper burns very hot, so there's eventually enough heat energy to shift the plug. It's messy though, and you get a bit of smoke leaking.

Professionals just leave a little blow torch in there for a few minutes.

Now I use an electric fire lighter

https://grenadier.co.uk/

In fact I never bother to use it to light the fire, but it is useful if the chimney doesn't draw. You just put it inside the stove and let it run for five minutes.

I know my chimney, I know when I need to use it, and this year I never had once any smoke in the room. (Famous last words there!)

By the way, now that spring is coming I'll mention that it's much better to leave the door of the stove slightly ajar if you're not using it. This allows a draft of air to dry out any moisture. The stove manuals say just leave the air valves open, but I've been told by a couple of installers that it's much better to leave the door open.

 

[Tony Lockhart]

I also like the idea of taking care of my wood out in the open so I can finally get to use it in the winter.

 

[35451]

Running a fire as above is an inefficient use of the wood. Without a decent amount of air you aren’t getting secondary combustion and are effectively only getting a low percentage of the woods potential heat output.

Also, what’s the point of heating a room downstairs when you’re upstairs in bed?

Extracting a steady high heat of a longer period of time is most efficient use of heat IME. Like I said been running the same stove of 13 years. I have tried the vents open approach. Lotsa flames, but ultimately less heat over a longer period, since the glowing charcoal always gets hotter than the yellow flames coming off the logs. the ash bed helps to hold it and stove body radiates. YMMV of course.

Not sure what model you run, by the Jotul we have also achieves satisfactory secondary combustion and 'air wash' with door vents closed and solely by using its baffle system plus the air ever-present in the flue. We are lucky to have a flue that draws well - to the point that we had to have a flue damper installed to slow burning. In a previous house I had a Villager stove and this was a far less efferent design and did need top door vents open to degree to draw properly. The Jotel is very efficient. Burning kiln dried wood with vents fully open is great for lighting and glass cleaning with air wash, but a bit too much for continual running.

The point of keeping fire in down stairs when we are in bed? We have 3 floor Victorian house with open plan lounge. Sometimes its better to keep a building ticking over warm, rather than let it cool, then reheat, cool then reheat etc. Old building stone walls absorb heat and once warm, can hold it for longer than new builds.

Stove is in recessed fireplace, once it has been going for a couple of days, the whole chimney breast that rises through the above two floors, becomes warm. It's like a big radiator and keeps the bedrooms noticeably warmer. Its double whammy since a warm flue, breast and stove are also more efficient, so if it does go out, it lights and draws again quickly.

Again YMMV.

Besides I like it...

 

[Tony Lockhart]

If we used our wood burner with the top vent open at all, or bottom vent open more than ‘only just’ it’d burn far too hot, and I’d be forever loading more wood. That’s not efficient.

I also leave it ticking over all night if it’s particularly cold out. For a quid’s worth of dried ash it’s got to be worth it.

 

[rubber]

clearview

 

[Tigerjones]

Extracting a steady high heat of a longer period of time is most efficient use of heat IME. Like I said been running the same stove of 13 years. I have tried the vents open approach. Lotsa flames, but ultimately less heat over a longer period, since the glowing charcoal always gets hotter than the yellow flames coming off the logs.

I'm afraid the science of burning wood says otherwise. You are probably only getting around 50% of a log's potential heat output which is obviously not efficient. The most heat is not from glowing charcoal but from the ignited gases given off during burning. A fire that is ticking over is not achieving good secondary combustion. Some say, including Lars Mytting in his excellent book Norwegian Wood, the best way to control the heat of a fire is by the amount of fuel on the fire with a good amount of air always present.

Not sure what model you run,

A Charnwood.

I like it...

Absolutely, it's your fire.

 

[Tigerjones]

https://jotul.com/int/guides/eight-tips-for-burning-wood :

AIR!

The wood is utilised in the best way when the draught control is fully open and the flames are intense. That will also reduce pollution, because gas particles are combusted and produce heat instead. Once your home is warm, the temperature is regulated by the amount of wood, not the air control.

OVERNIGHT HEATING

Very few wood stoves can burn longer than two to three hours on one wood load. The old way of closing the air supply so that the coals will smoulder overnight is a source of pollution and creates the risk of a chimney fire. In addition, the heat benefit is poor as the gases are not combusted and the energy is not utilised. The last wood load in the evening should be some bigger hardwood logs that burn as normal with the air vents open. Even if the fire dies out, the insulation in the house will keep the heat in. The stove and chimney will still be warm in the morning and it is no problem to get the fire going again.

 

[matt j]

Oh man, this is as nerdy as Hi-Fi. My Mum's having one fitted this year in readiness for next winter, seems like something else I've now got to read up about.

Although I refuse to get involved with selecting a stove, it's her money and she can find a stove and installer.

 

[35451]

If we used our wood burner with the top vent open at all, or bottom vent open more than ‘only just’ it’d burn far too hot, and I’d be forever loading more wood. That’s not efficient.

I also leave it ticking over all night if it’s particularly cold out. For a quid’s worth of dried ash it’s got to be worth it.

Same here. Obviously you also do get sufficient air in your stove without vents open to achieve combustion. Stoves aren't vacuums with vents closed. Otherwise it would simply go out!

Not at home at moment or I would post pic of fire, vents closed, burning with secondary combustion.

 

[35451]

I'm afraid the science of burning wood says otherwise. You are probably only getting around 50% of a log's potential heat output which is obviously not efficient. The most heat is not from glowing charcoal but from the ignited gases given off during burning. A fire that is ticking over is not achieving good secondary combustion. Some say, including Lars Mytting in his excellent book Norwegian Wood, the best way to control the heat of a fire is by the amount of fuel on the fire with a good amount of air always present.

.

Don't be afraid. It's not science, it's just one mans view and it may well apply to your installation. But not mine. As I said in #147 and you may have missed, I do get secondary combustion even with top vent shut. And my stove will burn for more than 3 hours. You haven't seen it but I have been looking at it fir quite a long time, and also at a less effective stove in a different property before that.

Another man from Yorkshire contradicts your Norseman with his *cough* science.

https://www.southyorkshirefirewood.com/burning-wood-on-a-stove.html

BURNING WOOD ON A WOOD BURNING STOVE
The single most important piece of advice on burning wood on a wood burning stove is to ensure that the wood is well seasoned, with a moisture content of below 30%. Burning wood that is not properly seasoned, not only provides an inefficient fuel source for your burner, but also produces resinous fumes that will soon build up deposits in your flue. This can present a flue fire risk and lead to reduced efficiency of your flue.

Another common mistake is feeding the fire too often, or keeping the door open for too long when feeding the fire. Every time the door of the stove is opened, accumulated heat is lost from the firebox that has to be built up again to get the stove up to its proper and most efficient running temperature. Try to minimise the amount of times that the stove door is opened. Refuel the fire and let the logs burn right down to hot embers before refuelling.

AND HERE IS HIS CORE SCIENCE AS APPLIES TO OUR INSTALLATION 1ST PARA

Using the air control valves on your stove
Every stove has its own burning characteristics and you will need to experiment and spend some time getting to know what works best with your stove. Even the same make and model of stove in different houses can act differently. The flue or chimney, or even the surrounding geography can have an effect on how airflows through a flue and affect the performance of a stove.

Most wood burning stoves and multi-fuel stoves have a bottom air vent and a top air vent. Wood burns best with a good bed of ash laid down in the bottom of the stove and an air supply from the top.

When lighting your stove, open both air vents fully. On initially lighting, it can be an advantage to crack the door open slightly to provide additional air flow through the firebox. Once the fire is established, close the door and then close down the bottom air vent gradually. If the fire dies right down at this point, open the bottom vent slightly for a bit longer until the fire is better established.

Once the fuel in the stove is burning properly, the temperature of the stove can be controlled using the top air vent. This can be quite an art to get this setting right. If the top vent is open fully, the fire may look good and as if it is burning fiercely, however, you will get through a lot of wood fuel and a lot of the heat will disappear up the flue. The idea is to throttle the top vent down until the wood is burning with a nice steady flame without dying down or burning fiercely. This reduces the flue temperature and gets the firebox as hot as possible, which then radiates heat into your room. Some wood burning aficionados will fit a magnetic flue thermometer so that they can monitor the flue temperature. The flue temperature needs to be hot enough to carry the fumes up the flue but being too hot is a sign that you are losing heat.

As I suggested YMMV. I will post some pics when i get around to it.

 

[Sue Pertwee-Tyr]

Oh man, this is as nerdy as Hi-Fi. My Mum's having one fitted this year in readiness for next winter, seems like something else I've now got to read up about.

Although I refuse to get involved with selecting a stove, it's her money and she can find a stove and installer.

Just make sure she knows to blind test the options properly.

 

[Tigerjones]

Don't be afraid. It's not science, it's just one mans view and it may well apply to your installation. But not mine. As I said in #147 and you may have missed, I do get secondary combustion even with top vent shut. And my stove will burn for more than 3 hours. You haven't seen it but I have been looking at it fir quite a long time, and also at a less effective stove in a different property before that.

Another man from Yorkshire contradicts your Norseman with his *cough* science.

Sorry it's not the Norseman's science it's the science of the process of burning wood (of which there is a plethora of information available), he's just man with a lot of experience regarding wood and stoves. The manufacture of your stove seems to agree with him and as I'm sure you'll agree Jotul know a thing or two about wood and stoves.

The point I was trying to make based on your original post that leaving a fire 'ticking over' is not an efficient use of wood and there is a whole lot of science behind that.

I don't disagree with the a lot of what South Yorkshire firewood say but then they just sell wood I presume?

 

[matt j]

As a basic guide is this ok, the chap seems to know what he's talking about

 

[Tony Lockhart]

As a basic guide is this ok, the chap seems to know what he's talking about

That’s pretty much what I do. If I left the controls open I’d have a raging furnace, a glowing flue, a living room at 30°C, and 2 new logs going in every twenty minutes.

 

[Tigerjones]

As a basic guide is this ok, the chap seems to know what he's talking about

Much better (again for efficiency and the environment) to build a top down fire with large logs at the bottom building up to the kindling on top. This way the flames are always at the top of the fire meaning gases given off are ignited, turned to heat and don't disappear up the chimney. A top down fire also produces a large bed of glowing coals and requires re-fueling less often. It also produces less creosote in the chimney.

 

[35451]

That’s pretty much what I do. If I left the controls open I’d have a raging furnace, a glowing flue, a living room at 30°C, and 2 new logs going in every twenty minutes.

Me too. It may be bad science, but it seems to work. With the fire in and all warmed through, I run at about a log an hour if we are home, but can happily leave it for longer if needed. The joy of low moisture kiln dried hardwood is that they also light really easily should fire die down and need rekindling.