Flue pipe at least 1.3 metres needed

[manxmike]

I need to replace the flue on my multi fuel burner, sadly I don't know what make it is but it has a 4 inch flue that appears to be single walled and is 1.3 metres to the ceiling. All the flue pipes I have found on line seem to be a max of 1 metre long - does anyone know of a supplier of longer pipes (and not for the price of gold!) I'm probably going to have to replace the roof fitting which has been there since the late eighties and is going to be a b*st*rd to remove - any hints and tips?

Edited April 10, 2017 by manxmike

[Dave Payne]

if keeping single then why not use a 1m and then a 500mm chopped to size with a coupling?

Edited April 10, 2017 by Dave Payne

[bizzard]

11 minutes ago, manxmike said:

I need to replace the flue on my multi fuel burner, sadly I don't know what make it is but it has a 4 inch flue that appears to be single walled and is 1.3 metres to the ceiling. All the flue pipes I have found on line seem to be a max of 1 metre long - does anyone know of a supplier of longer pipes (and not for the price of gold!) I'm probably going to have to replace the roof fitting which has been there since the late eighties and is going to be a b*st*rd to remove - any hints and tips?

They're generally just under 2 metres long from chandlers. There would be an extra few inches above the ceiling too. Limekiln chandlers 58''.

Edited April 10, 2017 by bizzard

[Mac of Cygnet]

3 hours ago, Dave Payne said:

if keeping single then why not use a 1m and then a 500mm chopped to size with a coupling?

You don't even need a coupling. Stove pipes are designed to fit one inside the one below.

[Martin Megson]

Midland chandlers sell 1.5 m lengths.  On mine the pipe should normally slide through the roof fitting. Once in place the gap needs to be sealed.

 

[X Alan W]

14 hours ago, Mac of Cygnet said:

You don't even need a coupling. Stove pipes are designed to fit one inside the one below.

I would prefer mine Outside the lower piece "smokey"

[dmr]

A single walled flue is traditionally made of bog standard thick walled steel tube that you can buy from your local steel stockists for not an enormous amount of money. It think it comes in three metre lengths but most will cut it to whatever length you need. If it needs any bends in it then a boaty welder will do this for again not a huge amount of money.

Paying a welder will likely be cheaper than using thin tube and messing amount with couplings and elbows etc and will look better too.

...............Dave

[Mac of Cygnet]

1 hour ago, X Alan W said:

I would prefer mine Outside the lower piece "smokey"

Not a good idea, especially in woodburners.  Tar trickling down would eventually find its way out.  Fitting the upper inside the lower is the recommended method.

[adrianh]

If you are just looking for steel tube try these people https://www.metals4u.co.uk/mild-steel/c6/tube/c2239/tube/c56

[X Alan W]

On 11/04/2017 at 11:59, Mac of Cygnet said:

Not a good idea, especially in woodburners.  Tar trickling down would eventually find its way out.  Fitting the upper inside the lower is the recommended method.

Our House in France has 2 wood burner stoves a 9KW & a 14KW both with exposed SS flue pipes 150mm dia the flues were renewed on house purchase in 2004 & the lower section is fitted inside the next section they were installed by a certified " stove fitter/installer" & a certificate issued ( Required in our dept )  the flue is inspected & a new certificate issued if OK every 5 years  To date I have had 2 inspections & new certificates issued & no comment has been made on the way of the flue is assembled & no tar or any form of gunge has emerged at any of the joints I have also asked the installer on the orientation of the flue to be told lower inside the next section,Maybe different in the UK. In the winter they run 24/7

[bizzard]

21 minutes ago, X Alan W said:

Our House in France has 2 wood burner stoves a 9KW & a 14KW both with exposed SS flue pipes 150mm dia the flues were renewed on house purchase in 2004 & the lower section is fitted inside the next section they were installed by a certified " stove fitter/installer" & a certificate issued ( Required in our dept )  the flue is inspected & a new certificate issued if OK every 5 years  To date I have had 2 inspections & new certificates issued & no comment has been made on the way of the flue is assembled & no tar or any form of gunge has emerged at any of the joints I have also asked the installer on the orientation of the flue to be told lower inside the next section,Maybe different in the UK. In the winter they run 24/7

That's my opinion too. Safer to have a bit of goo trickling down than poisonous fumes leaking out.

[Mac of Cygnet]

Every fitting guide and all manufacturers' instructions that I have been able to find (an example here) recommends fitting the upper into the lower.  If smoke or fumes are going to come out of a joint then they will do so whichever way up it is, and if they are, then there are problems elsewhere.

[bizzard]

11 minutes ago, Mac of Cygnet said:

Every fitting guide and all manufacturers' instructions that I have been able to find (an example here) recommends fitting the upper into the lower.  If smoke or fumes are going to come out of a joint then they will do so whichever way up it is, and if they are, then there are problems elsewhere.

Fumes are hot and only want to rise upwards. Its unlikely that they would double back and go downwards to escape.

[Mac of Cygnet]

6 hours ago, bizzard said:

Fumes are hot and only want to rise upwards. Its unlikely that they would double back and go downwards to escape.

Fumes will only come out of anywhere but the top of the chimney if there is a blockage further up, or a downdraught.  In these cases, they will certainly 'double back'. The normal updraught in a chimney normally creates a negative pressure which prevents any fume or smoke escaping, whichever way the joint is facing.  As I said before, the recommendation of all manufacturers of stoves and flues, and all 'how to' sites I have found is to fit the upper into the lower.

This debate has appeared several times on stove, DIY, and other forums, and always reaches the same conclusion - upper into lower.

Edited April 16, 2017 by Mac of Cygnet
Too many 'normals'!