Efficient chimneys

[Nikki]

I read this today:

Install a new chimney straight up through the warm space of the house, not out a wall and up the outside. The physics of why this is important is too complicated to get into here, but take it from me, outside chimneys are the single biggest reason why woodstoves smoke into houses. If you never want your stove to smoke when you light a fire; or to stink when it is not in use; put the chimney inside.

Anyone have an easy explanation, or website? I like to understand these things. Especially if I'm going to have to convince a builder here. Is it that necessary?

[Martin]

in a word - cobblers!
Sounds like whoever wrote that has nil grasp of physics, chimneys, or common sense!
There are good valid reasons for perhaps having a solid chunk of bricks/masonry which can absorb the heat, and slowly release it into the property, but a chimney can be in or outside, and work well!
There are good sound safety reasons for using a "Hertas" registered fitter of stoves/flues - not least, they'll make sure it works, and won't gas you!

[Smooth Hound]

I m not sure, could it not be soething to do with hot air rising, i know that when you light a cold fire and the chimney is cold as well, you do get a bit of blow back, but once you chimney has warmed the extra heat helps the smoke to rise, so pulling more smoke up from the fire giving you a good draw. where as if the chimney is out side it would be alot cooler and possibly interfere with the draw.
I have no idea whether this is right or not , but just a thought really

[old tree man]

We sometime have a problem depending on wich way the wind is blowing, but have never had a problem with heat transference its always snug and cosy especially in this weather
Russ

[Smooth Hound]

is your chimney inside or outside ?

[old tree man]

inside and only a small fire

[snapdragon]

ours is inside - and been in use for a hundred years so I guess it works ok

[Thomzo]

This house has a chimney that was originally on an outside wall. A garage has since been built on that side of the house but provides little insulation and is not heated. I still get a really good draw but then I am at the top of a hill.

In a previous house, I had an extension built. I put a chimney on an outside wall for a Rayburn. That did struggle to get going sometimes. I used to have to open the back door and the window to get a good enough draught which wasn't pleasant when it was wet or cold.

All my other houses have had chimneys on internal walls. Never on an outside wall.

Zoe

[Arimiel]

Hm... the smoke issue seems very fishy to me
But I think it is't about prakticality but about economy...
thats because the heat of the chimney will be better used inside.... if you put them up outside... or on the outer wall there will be a lot of heat lost....in fact a lot of the energy stored in the materials burned will go into the air unused....
Seymour thought about that too and desinged a chimney that as much warmth as possible... ahmn.... its called the Fachoncle-furnance...
i tried to upload a picture.... but my whole family seems to be online... it would takes weeks to upload.....
And to describe it hier would take hours too... so you have to take my word that seymours design is a fasinating answer to the chinmey problem.... [/img]

[Fahrenheit]

Hi there,

What they're saying is not entirely correct. Although a chimney that is inside the house will work better. This is because the chimney will never get as cold as one that is exposed on the outside of the house. We all know a warm chimney works better. Also you'll get more heat benefit from an internal chimney as the chimneybreast works as a huge heat sink/radiator.

As for it solving all your smoking back issues it will not.

There could be several explanations for why your room smells of smoke. It's usually caused by down draught or low pressure on the side of your house where an air-vent is located.

There is a climatic condition which can cause a problem and is more likely to occur when a chimney is exposed. This problem causes your chimney to work in the opposite direction filling your room with smoke. It happens when the air in the flue is colder than the air outside. This means it's heavier and tends to sink. This can only really be overcome by heating up the flue.

An internal chimney would not be affected as much by this as the air in the flue tends to be warmer as it is indoors.

Also you usually find you get greater soot deposits in exposed chimneys due to the stack being colder and the gasses condensing quicker.

Kind Regards,
Chris Phillips

[Millymollymandy]

I'm having a problem with my wood burner smoking when we open the door to put more wood on. Never had that problem before. It's been swept, and the wood is well seasoned. It's very annoying!

[Nikki]

Although a chimney that is inside the house will work better. This is because the chimney will never get as cold as one that is exposed on the outside of the house. We all know a warm chimney works better. Also you'll get more heat benefit from an internal chimney as the chimneybreast works as a huge heat sink/radiator.

Hi Chris,

Thanks for the sensible explanation. It's along the lines of what I was guessing - it's inside so you get te benefit of a radiator effect.

Wit the smoking and soot issues to boot, seems a good idea to have an internal one. ???

I now need to decide where to design it - in or out.... hmmmm....

[Welsh Girls Allotment]

I'm having a problem with my wood burner smoking when we open the door to put more wood on. Never had that problem before. It's been swept, and the wood is well seasoned. It's very annoying!

mine does this sometimes and I have noticed that it is coming from the door itself - when it gets very hot it burns the caked on stuff from the door, I give it rub with a wire brush and it seems to sort it

regarding poor draw you can fit a gadget to the top of the chimney that spins around and increases the updraft - little silver thing with fins - cannot think of the correct name - I am sure someone know what I mean