Woodburner kw output and flue diameter help

[Lukey-Loki]

Hello chaps.

Hope this is in the right place...

 

Looking to get a woodburning stove. I've had a couple of people come round to look at lining chimney. Both guys were saying different things about flue diameter.

 

Am I right in thinking the diameter of the stove flue outlet and kw output of stove dictates the diameter of chimney lining?

 

Do they need to insulate the chimney liner in chimney itself?

(I'll be burning wood, possibly with a bit of coal sometimes)

 

The living room is -

H - 9'

L - 20'

W - 15'

 

What sort of kw output would I need for a room that size?

 

Thank you!

[Stubby]

If you google there is loads of places that give you a formula that works it out for you . Just put in your dimensions and it will give you min output of a stove you need to heat that room . Remember though that you could heat more than just that room . I prop all the internal doors open and heat the whole hose with mine . Flue liner will depend on stove spigot . Most are 6" now . . Mine went inside original clay liners ( 7.5" ) so no need/room to insulate but if its not lined already always good to do so .

[Stubby]

Oh would recomend any of the Burley stoves . very efficient , mine runs at 98% . They are wood only though not multi fuel .

[Alycidon]

Hello chaps.

Hope this is in the right place...

 

Looking to get a woodburning stove. I've had a couple of people come round to look at lining chimney. Both guys were saying different things about flue diameter.

 

Am I right in thinking the diameter of the stove flue outlet and kw output of stove dictates the diameter of chimney lining?

 

Do they need to insulate the chimney liner in chimney itself?

(I'll be burning wood, possibly with a bit of coal sometimes)

 

The living room is -

H - 9'

L - 20'

W - 15'

 

What sort of kw output would I need for a room that size?

 

Thank you!

 

Say 6m x 4.5m = 27sqm x 2.5m = 67 cu m.

 

Poor insulation divide by 12 (5.5kw), average ins divide by 14 (5kw), good ins divide by 16 (4kw) roughly.

 

Stoves of that size usually have a flue outlet of 125mm diameter, building regs stipulate that unless the stove is DEFRA approved to burn wood in a smoke control area a 150mm flue liner be used. If the stove is DEFRA approved then we can use a 125mm liner.

 

Fitting a flue liner is not legally compulsory, however it will help the stoves efficiency. Some inset stoves due to their design must be fitted with liners. Providing your chimney is sound and not to large then you should be OK without a liner but anything built before 1950 should really be lined. Some companies will not install a stove without installing a liner, this is their choice.

 

5.1kw or above you will need a permanently open air vent in the room, if a new house tested for air tightness air vent is needed anyway.

 

Steer clear of all chinese made crap, average life 3-5 years. Make sure that your stove is actually made in UK or Europe, some major brands are now having their stoves made in the far east, as a result build quality is not what it was.

 

A

Edited March 12, 2013 by Alycidon

[Alycidon]

Oh would recomend any of the Burley stoves . very efficient , mine runs at 98% . They are wood only though not multi fuel .

 

Burley site states efficiency at 84-89 % depending on model. at 98% that would imply no heat is lost up the flue pipe.

 

Efficiency figure is not to be taken to literally at there are several ways of measuring it, net and gross that we usually use in the UK and EN which is usually used for stoves tested in Europe. A stove tested under EN will give about a 6% higher reading than the same stove tested in the UK and given a gross result. This is as I understand it (and I stand to be corrected if wrong) due to the moisture present in the wood used for uk test, EN test are usually done using smokeless fuel.

 

Most Burley do have a multifuel option, but I dont think they are made in Europe.

 

A

[Stubby]

Burley site states efficiency at 84-89 % depending on model. at 98% that would imply no heat is lost up the flue pipe.

 

Efficiency figure is not to be taken to literally at there are several ways of measuring it, net and gross that we usually use in the UK and EN which is usually used for stoves tested in Europe. A stove tested under EN will give about a 6% higher reading than the same stove tested in the UK and given a gross result. This is as I understand it (and I stand to be corrected if wrong) due to the moisture present in the wood used for uk test, EN test are usually done using smokeless fuel.

 

Most Burley do have a multifuel option, but I dont think they are made in Europe.

 

A

 

Sorry . Got my eight and my nine back to front . My stove is the Burley Holywell . rated at 5kw but I am sure this is a nominal figure . It does heat the whole house which would suggest it is more than that . Maybe its to get round the room vent thing ? Anyway min is wood only but that suits me as I get aplenty !

[Lukey-Loki]

Thank you guys for the helpful info. Much appreciated!

 

I'm waiting to see what maximum diameter of flue is possible (old 4 story house, we're in lower ground floor flat).

 

As to the air vent necessity - there are a couple of air bricks in the external wall (and cat flap). Are these sufficient or are the regs referring to something more specific?

[mendiplogs]

Say 6m x 4.5m = 27sqm x 2.5m = 67 cu m.

 

Poor insulation divide by 12 (5.5kw), average ins divide by 14 (5kw), good ins divide by 16 (4kw) roughly.

 

Stoves of that size usually have a flue outlet of 125mm diameter, building regs stipulate that unless the stove is DEFRA approved to burn wood in a smoke control area a 150mm flue liner be used. If the stove is DEFRA approved then we can use a 125mm liner.

 

Fitting a flue liner is not legally compulsory, however it will help the stoves efficiency. Some inset stoves due to their design must be fitted with liners. Providing your chimney is sound and not to large then you should be OK without a liner but anything built before 1950 should really be lined. Some companies will not install a stove without installing a liner, this is their choice.

 

5.1kw or above you will need a permanently open air vent in the room, if a new house tested for air tightness air vent is needed anyway.

 

Steer clear of all chinese made crap, average life 3-5 years. Make sure that your stove is actually made in UK or Europe, some major brands are now having their stoves made in the far east, as a result build quality is not what it was.

 

A

 

HI MATE we had 8kw stove in our room is 7mt x 5mt and a 8kw was just no good at all but then our barn is 200 years old plus now we have a 16kw i love it large logs go on nice thanks jon

[Lukey-Loki]

HI MATE we had 8kw stove in our room is 7mt x 5mt and a 8kw was just no good at all but then our barn is 200 years old plus now we have a 16kw i love it large logs go on nice thanks jon

 

Nice one Jon. I bet it's always toasty in your place.

[adie.k]

hi.

there is nothing in the regs that says you have to have a liner. but if you are unsure of the condition of your chimney, it is always better to stick on the side of caution. as far as the insulation goes, the warmer you keep the flue gases, the less they will tar up your chimney and the quicker they move up and out. stops condensation in the chimney, so again, it would be prudent to do it.

if you have a modern house a 5 kw stove will be fine in a room of that size. anything over 5kw and you need an air vent.

the flue liner size should never be smaller than the collar on the stove and if the stove is half decent with a 5kw output, the fluesize will be 125mm dia. some installers put in a 6" flue but the building regs were changed to allow a stove to b fited under a 5" because of the increased efficiency of modern appliances.

 

hope this helps.

 

adie.k