Wood Burner Flue Length

[martin69]

I am building a single storey lean to type extension and want to put a wood burner in it with a twin wall s/s flue but am having extreme difficulty making sense of the building regs concerning this.

They seem to indicate that as long as it is over 2.3m from the neighbouring buildings it needs to be only 2.3m horizontally from the roof and 1m above the intersection of the top of the flue and the roof.

But elsewhere it says a minimum length of 4.5m enough as long as the above is satisfied. If this is the case, I would end up with a 3.5m chimney sticking out of the roof like a power station!

Is this 4.5m a rule or guidance, and is there a required minimum length of flue for regulations and safety?

Many thanks

 

[Tibbot]

The 4.5m minimum is so the flue works,

 

[Norcon]

They seem to indicate that as long as it is over 2.3m from the neighbouring buildings it needs to be only 2.3m horizontally from the roof and 1m above the intersection of the top of the flue and the roof.

Those dimensions refer to the terminal position. (ie- flue outlet)
Not the flue!
You'll need a Class 1 flue. (Twin wall insulated to BS - 4543)
Then have it exiting the lean too roof, close to the existing building to suit the standard stand off securing brackets.
When you've passed the minimum flue draft dimension required then ascertain if your flue meets the terminal dimension requirements.

 

[DeltaT2]

They seem to indicate that as long as it is over 2.3m from the neighbouring buildings it needs to be only 2.3m horizontally from the roof and 1m above the intersection of the top of the flue and the roof.

Those dimensions refer to the terminal position. (ie- flue outlet)
Not the flue!
You'll need a Class 1 flue. (Twin wall insulated to BS - 4543)
Then have it exiting the lean too roof, close to the existing building to suit the standard stand off securing brackets.
When you've passed the minimum flue draft dimension required then ascertain if your flue meets the terminal dimension requirements.

Is a Class 1 chimney not a brick/block built chimney mate? Certainly used too be!

 

[Norcon]

Dunno Delta.
I was referring to the likes of these.... Pre fabricated Class 1.
http://tinyurl.com/6j9xnoe
Approved by HETAS.

Edit!
But you are probably correct..

Google wrote.

A Class 1 flue is the most versatile of all flues. It is 7” in diameter and is usually found in properties with conventional chimneys, which have, at sometime had open coal fires in them. Most models of gas fire will fit into a Class 1 flue. You will generally find that gas fires with a high heat output or fires which are slightly less efficient will require a 7” flue in order to disperse the heat more effectively which is lost up the chimney.