[nicknoxx]

Hi all

Our chimney is lined with a 6" flue liner. Is is possible/advisable to
try to connect a woodburner with a 7" flue to the liner, and if not,
what problems are there likely to be?

thanks in advance

[andrew]

nicknoxx wrote:

Hi all

Our chimney is lined with a 6" flue liner. Is is possible/advisable to
try to connect a woodburner with a 7" flue to the liner, and if not,
what problems are there likely to be?

It's not recommended because the stove with the 7" flue probably needs that
size to get the gases away, flue gas massflow is proportoinal to heat
output.

The chimney (and its seal to the stove) maintains a depression in the stove
so that any small leaks allow air to enter the stove and prevent noxious
gases getting into the room. Effectively constricting the flue gases will
reduce this depression (or draw).

OTOH a 6" pipe is the mandatory minimum for a woodburner even if the stove
outlet is 5".

AJH

[[email protected]]

On Nov 18, 7:28*pm, nicknoxx
wrote:
Hi all

Our chimney is lined with a 6" flue liner. Is is possible/advisable to
try to connect a woodburner with a 7" flue to the liner, and if not,
what problems are there likely to be?

thanks in advance

Check part J of the building regs on heat producing appliances - ISTR
this is regulated:

http://www.planningportal.gov.uk/bui...cuments/partj/

[Michael Chare]

"nicknoxx" wrote in message
...
Hi all

Our chimney is lined with a 6" flue liner. Is is possible/advisable to try
to connect a woodburner with a 7" flue to the liner, and if not, what
problems are there likely to be?

thanks in advance

Probably not! But you could ask the stove manufacturer.

Flue length could be a factor. I think long flues cause more draft which
might be a compensating factor.


--
Michael Chare

[Jim K[_3_]]

On Nov 18, 8:03 pm, andrew wrote:

OTOH a 6" pipe is the mandatory minimum for a woodburner even if the stove
outlet is 5".

really? gotta link?

Jim K

[andrew]

Jim K wrote:

On Nov 18, 8:03 pm, andrew wrote:

OTOH a 6" pipe is the mandatory minimum for a woodburner even if the
stove outlet is 5".

really? gotta link?

Jim K

It's in the regs part J and guidance notes but a quick search to save me
reading them gives:

http://www.stovesonline.co.uk/stove-flue-sizes.html

"
Stove flue sizes

The flue size (diameter or cross sectional area) must not be smaller than
the size of the stove outlet.

It is in the building regulation guidance notes that the minimum flue size
for stoves is as follows:

up to 20kW burning smokeless fuel - Minimum 125mm diameter.
up to 30kW burning any fuel - Minimum 150mm diameter.

If the stove is Defra Exempt and has a 125mm outlet then a 125mm diameter
flue may be used. This is a recent update (Oct 1st 2010) to the regs.

So the regs recommend a minimum flue size of 150mm for any stove (on which
wood could be burnt) unless it is Defra Exempt.
Many stoves come with a 125mm flue outlet which then requires upsizing to
150mm (unless Defra Exempt).

We asked Barrie Meridew, independant chimney consultant and he said:
stove quote 1

It should be emphasised that if anything other than smokeless fuel is likely
to be burned, a 150mm minimum flue should be used. Personally, and for
safety reasons, I would never fit a 125mm flue on any solid fuel appliance,
150mm should be the minimum
stove quote 2 "

Now what's the cheapest source for 150mm steel flue in 500mm sections, I've
got to poke some, with retrofitted insulation up a 9" clay flue liner to
get the gas velocity up on a short chimney.

AJH