Flue vent for a wood burning stove

[thomsewe]

Hi

I have a wood burning stove that can vent the exhaust gasses from either the top or the back. It is currently configured with the top vent.

As hot air rises am I wasting heat because all the hot gasses are being taken straingt up the chimney and not being given a chance to heat the case of the stove and radiate warmth into my room. If the exhaust vent is moved to the back of the fire which is lower down would this not increase the heat at the top of the stove and thus rediate more heat into my room?

Thanks Tom

[Adrian]

Not sure that it would make all that much difference - possibly not worth the effort of changing it ? Maybe ask the manufacturer ?

If the stove's any good then the hot gases will be passing over a baffle or plate in the top of the stove before going up the flue - my experience of wood-burners is that, unless you have a very large room, your usual problem is too much heat rather than too little !

Regards Adrian

[robgraham]

I will echo the 'too much heat' bit.

Certainly if you have a large room to heat then one way of increasing the heat - or should I say - reducing the heat loss, is to use a steel flue, from the top of the stove, within the room so that you increase the radiating surface. It does depend on the room style of course as to how good that looks !

Rob

[Adrian]

- You've been there too ! In our last place in Suffolk we had an enormous wood/coal-burning stove in the front room (which was 18ft x 24ft). The stove had a built in boiler, and worked the central heating and domestic hot water.

When running 'flat out' it was allegedly capable of putting 8kw into the heating circuit and a further 4kw directly into the room - but we never dared run it that hard - it was unnecessary...

We had a cast-iron flue from the stove up into the chimney. I've got a feeling that you are required to use a double-skinned (= insulated) flue pipe nowadays... but I'm not certain about this...

The other thing to be careful of is over-cooling the flue gases - as if the temperature drops too far then you can get tars condensing in the flue pipe - which is bad news....

Regards Adrian

[thomsewe]

Hi

Thanks for your replys.

The room I am heating is fairly big 7.5 meters by 5.5 meters by 3 meters high. If I keep the room door closed then there is plenty of heat for the whole room. However to reduce the quantity of oil I burn (in my central heating system) I leave the room door open to add some warmth to the rest of the house.

As I use the stove every day during the winter and a fair bit in late autum and early spring I would like to conserve my wood supply as much as possiable by getting the maximum efficency from the wood I do burn.

The stove is made by Jotul and has a baffel at the top which the gasses must pass by before reaching the top of the stove and the exhaust vent.

It is a good point about the steel pipe which I currently have approx

1 meter exposed in the room. This would also increase by a further 250 mm if I used the back vent.

I am relativly confident about the current temprature of the flue gasses as the last time I had the chimney swept I was informed ther was hardley any build up in the chimney. This is most likley caused by the wook being burnt has been left to dry for at least 3 years.

Thanks for you help

Tom