Hello

I am new to this group but I'm hoping some fireplace expert can point
me in the right direction with a solution to a problem with my new
fireplace.

I recently extended my living room which would have resulted in my
existing fireplace being off centre. To solve this, my builders
blocked up the old fireplace and made a new opening in the new centre
of the wall, joining this to the existing chimney about 2 metres up.
The chimney is a 30s unlined one. The connection beteween fireplace
and chimney is by a clay flue pipe. The displacement (ie. amount the
fireplace was moved) is about 1.25m.

Now the old fireplace drew perfectly - except it was a 70s built rough
stone horror (just like my granny had in her bungalow built in 1972).
The new one has only been used once, but a small proportion of the
smoke 'leaked out' into the room, making its use a bit untenable! It
wasn't enough to suggest that the chimney was blocked, but rather that
the chimney wasn't drawing as well as it had.

I suspect that the problem comes from a number of factors:

- The opening is taller than it was, so there is a bigger gap between
grate and flue. The builders made a brick insert in the shape of a
gothic arch, 85cm high by 58 wide, 35 deep. The old opening was lower
- around 70cm, I think.

- The clay pipe is roughly 25cm x 25cm, which I suspect is less than
the old one (but I have to be honest and admit that I never did stick
my head up the old opening).

- There is now a bend in the flue which (maybe) reduces the draw
efficiency.

Can anyone tell me what is likely to be the problem and how I should
solve it? I had wondered whether buying a hood to reduce the distance
between the fire and the effective top of the opening would help? If
so, does anyone know where I can get one in the South London (Croydon)
area?

When I'm feeling brave I intend to try putting the grate up on bricks,
to see if raising it closer to the top of the opening will improve
things. Sensible or just a license to smoke some people?!

Any other ideas would be most welcome!

Tim P

I'm no exoert but had one thing has occurred to me. Has the new work made
the room more draught proof and the fire can't 'pull' enough air through?

Good thought - it is a bit more sealed, but it always was quite draft
free. We did try opening a window when we filled the room with smoke,
but it didn't seem to improve things much!

How sharp are the bends they have put in?

Also, is it clear that the smoke in not coming from the flue but rather just
from the fireplace opening? I wouldn't have thought that a raised height of
15cm or so should make too much difference, although it could until the fire
has got nice and toasty.

The correct way to think of a fire and flue is as a machine. The fire is
the the engine and needs the necessary input to run correctly. There should
be sufficient air available to it and it will not run efficiently until
fully hot and the exhaust gases are running fast up the flue.

Another thought - what terminal do you have fitted to the chimney pot, if
any?

Rob

I had this issue, the opening was too tall, the local fire shop sole me a small "hood" to fit in the top or the opening.

Rick

On 4 Dec 2003 11:27:44 -0800, (Tim Pollard) wrote:
Hello

I am new to this group but I'm hoping some fireplace expert can point
me in the right direction with a solution to a problem with my new
fireplace.

I recently extended my living room which would have resulted in my
existing fireplace being off centre. To solve this, my builders
blocked up the old fireplace and made a new opening in the new centre
of the wall, joining this to the existing chimney about 2 metres up.
The chimney is a 30s unlined one. The connection beteween fireplace
and chimney is by a clay flue pipe. The displacement (ie. amount the
fireplace was moved) is about 1.25m.

Now the old fireplace drew perfectly - except it was a 70s built rough
stone horror (just like my granny had in her bungalow built in 1972).
The new one has only been used once, but a small proportion of the
smoke 'leaked out' into the room, making its use a bit untenable! It
wasn't enough to suggest that the chimney was blocked, but rather that
the chimney wasn't drawing as well as it had.

I suspect that the problem comes from a number of factors:

- The opening is taller than it was, so there is a bigger gap between
grate and flue. The builders made a brick insert in the shape of a
gothic arch, 85cm high by 58 wide, 35 deep. The old opening was lower
- around 70cm, I think.

- The clay pipe is roughly 25cm x 25cm, which I suspect is less than
the old one (but I have to be honest and admit that I never did stick
my head up the old opening).

- There is now a bend in the flue which (maybe) reduces the draw
efficiency.

Can anyone tell me what is likely to be the problem and how I should
solve it? I had wondered whether buying a hood to reduce the distance
between the fire and the effective top of the opening would help? If
so, does anyone know where I can get one in the South London (Croydon)
area?

When I'm feeling brave I intend to try putting the grate up on bricks,
to see if raising it closer to the top of the opening will improve
things. Sensible or just a license to smoke some people?!

Any other ideas would be most welcome!

Tim P

Rick Dipper wrote:

I had this issue, the opening was too tall, the local fire shop sole me a small "hood" to fit in the top or the opening.



Ok, I hjad this problem in SPADES when the dumb builder built my inglenooks.

There is a page on the web that I discovered that covers this all in detail.

There are a few salient points you need to know.

The most important is that the fire APERTURE - if you like the area
bounded by the grate, the sides of the fire and the lintel over teh top
of it should be no more than 5, or at most 7 times the cross sectional
area of the flue. Any more than this and the velocity of air being drawn
into the fire will not be enough to suck stray smoke into the fire etc etc.

The second point is that starting fires with e.g. papaer and damp
kindling, does not produce enough heat to overcome the resistance of the
cold air trapped in the flue. Many canadian contributors to the sites I
found that - especially when they had chimneys running up an outside
wall - they needed to get a small blaze going first to 'start' the
chimney. This efect is worsened if the flue is longer and not vertical:
It takes more to start it.

In my case I am in teh process of installing giant cowls to reduce the
effective area of 'draw'...so far with pretty decent results. I couldn't
get teh aperture down to ideal, but its now small enough that it takes
some severe sideways draught to allow a little somoke to escpae. ...in
your case a simple strip along the top of the fire may be enough, or it
may be more aesthetically pleasing to simply raise the grate. My in-laws
have an amazing fire which is actually in the MIDDLE of the wall, with a
log store underneath. Just raising the grate on a couple of blocks
should be enough to stop the problem, or you can test by taping a sheet
of cardboard over the top of the fire aperture.

To ensue the chimney 'starts' well, you need s good blaze from the word
go. That means newspaper and dry kindling, or better a firelighter, or
even as I sometimes do, ten minutes with a plumbers blowlamp to get the
fuel going. Once the cghimney is going, you need to mae sure the room
has adequate ventilation - I have underfloor ducts for the fire to avoid
draughts, they work very well. ANY negative pressure in the room will
stop the fire drawing, sister-in-law had a dreadful fire that wouldn't
draw unless the doors were open. Eventually it was left unattended and
burnt the house down. Literally and seriously.

So the key to a good fire is not too much aperture to flue, warm flue,
and adequate room ventilation and a decent hearth space to avoid
exploding material getting onto flammable stuff. The latter two points
are covered by building regulations which are utterly sensible and
should be studied and applied (or exceeded) rigorously. The design of
flues and apertures is a lost art these days, and should be the subject
of intense google searches for what info there is out there.








Rick

On 4 Dec 2003 11:27:44 -0800, (Tim Pollard) wrote:

Hello

I am new to this group but I'm hoping some fireplace expert can point
me in the right direction with a solution to a problem with my new
fireplace.

I recently extended my living room which would have resulted in my
existing fireplace being off centre. To solve this, my builders
blocked up the old fireplace and made a new opening in the new centre
of the wall, joining this to the existing chimney about 2 metres up.
The chimney is a 30s unlined one. The connection beteween fireplace
and chimney is by a clay flue pipe. The displacement (ie. amount the
fireplace was moved) is about 1.25m.

Now the old fireplace drew perfectly - except it was a 70s built rough
stone horror (just like my granny had in her bungalow built in 1972).
The new one has only been used once, but a small proportion of the
smoke 'leaked out' into the room, making its use a bit untenable! It
wasn't enough to suggest that the chimney was blocked, but rather that
the chimney wasn't drawing as well as it had.

I suspect that the problem comes from a number of factors:

- The opening is taller than it was, so there is a bigger gap between
grate and flue. The builders made a brick insert in the shape of a
gothic arch, 85cm high by 58 wide, 35 deep. The old opening was lower
- around 70cm, I think.

- The clay pipe is roughly 25cm x 25cm, which I suspect is less than
the old one (but I have to be honest and admit that I never did stick
my head up the old opening).

- There is now a bend in the flue which (maybe) reduces the draw
efficiency.

Can anyone tell me what is likely to be the problem and how I should
solve it? I had wondered whether buying a hood to reduce the distance
between the fire and the effective top of the opening would help? If
so, does anyone know where I can get one in the South London (Croydon)
area?

When I'm feeling brave I intend to try putting the grate up on bricks,
to see if raising it closer to the top of the opening will improve
things. Sensible or just a license to smoke some people?!

Any other ideas would be most welcome!

Tim P

On Sat, 06 Dec 2003 10:43:35 +0000, The Natural Philosopher
wrote:



To ensue the chimney 'starts' well, you need s good blaze from the word
go. That means newspaper and dry kindling, or better a firelighter, or
even as I sometimes do, ten minutes with a plumbers blowlamp to get the
fuel going. Once the cghimney is going, you need to mae sure the room
has adequate ventilation - I have underfloor ducts for the fire to avoid
draughts, they work very well. ANY negative pressure in the room will
stop the fire drawing, sister-in-law had a dreadful fire that wouldn't
draw unless the doors were open. Eventually it was left unattended and
burnt the house down. Literally and seriously.

On that subject, what precautions do you need to take to avoid small
burning particles that are going up the chimney from landing on the
roof and burning it? Just curious..
..andy

To email, substitute .nospam with .gl

Andy Hall wrote:

On Sat, 06 Dec 2003 10:43:35 +0000, The Natural Philosopher
wrote:



To ensue the chimney 'starts' well, you need s good blaze from the word
go. That means newspaper and dry kindling, or better a firelighter, or
even as I sometimes do, ten minutes with a plumbers blowlamp to get the
fuel going. Once the cghimney is going, you need to mae sure the room
has adequate ventilation - I have underfloor ducts for the fire to avoid
draughts, they work very well. ANY negative pressure in the room will
stop the fire drawing, sister-in-law had a dreadful fire that wouldn't
draw unless the doors were open. Eventually it was left unattended and
burnt the house down. Literally and seriously.


On that subject, what precautions do you need to take to avoid small
burning particles that are going up the chimney from landing on the
roof and burning it? Just curious..


Fisrt of all, most thatch house that burn, don't burn from outside. The
classic cases are electrical shorts or hot flue gasses escaping via a
cracked flue with rotting mortar, and setting teh dry thatch underneath
aliht.

To this end, modern thatched rooves are subject to the followng regulations

- final exit height of stack and pot MUST be 2.2 meters above thatch
ridge etc. this is reckined to be enough to carry sparks away.
- thatched roof must be a minium distance from boundary of property, or
(in my case) there is no adjacent buildings, nor planning consent or
indeed possibility of such to put up a property closer than, IIRC 5 meters.
- fireproof breathable board (supalux/masterboard/multiboard is used
UNDER the thatch to reduce chances of an attic fire setting thatch alight.
- smoke alarms everywhere. This is pretty standard anyway no matter what
the roof.
- no timber stricures are allowed closer than I think 20mm to teh
stacks. In my case we used supalux board spacers and metal hangers to
carry the ridge to stack loads.
- all flues must be lined with ceramic flue liners or steel insulated
liners.
- some fairly srong regs on use of e.g. ceiling mounted spots under
thatched rooves. Mine are actually under fully boarded attic floors.


That takes care of most of the normal mechanisms. The one remaining
poetntial problem is a chimney fire, which can indeed eject huge
quantities of burning material. In normal use the flue gases cool down
fast as they rise up teh chimney, and no burning material is carried up.

Chimney fires are all about dirt flues and burning too hot. If you get
one, you puit teh fire out below immediately with buckest of water, and
block teh flue to starve the oxygen. It goes out n a few seconds. Its
very unlikely that it would hurt damp wet thatch, but I have a hose
always connected outside anyway.

The fire that hapopened was to a timber farmed house but tiled roof. The
fire was piled high, surrounded by firewood and newspapers, had no
guard, a very small hearth and a history of rolling logs off the front.
Which is probably what it did, onto the carpet. In short, it was
criminally negligent to leave it burning while we all went down the pub.

Open fires need to be treated with respect. But so does a motor car. We
are less used to fires, than cars, these days...


.andy

To email, substitute .nospam with .gl

On Sat, 06 Dec 2003 13:47:00 +0000, The Natural Philosopher
wrote:

..


Fisrt of all, most thatch house that burn, don't burn from outside. The
classic cases are electrical shorts or hot flue gasses escaping via a
cracked flue with rotting mortar, and setting teh dry thatch underneath
aliht.

To this end, modern thatched rooves are subject to the followng regulations

- final exit height of stack and pot MUST be 2.2 meters above thatch
ridge etc. this is reckined to be enough to carry sparks away.
- thatched roof must be a minium distance from boundary of property, or
(in my case) there is no adjacent buildings, nor planning consent or
indeed possibility of such to put up a property closer than, IIRC 5 meters.
- fireproof breathable board (supalux/masterboard/multiboard is used
UNDER the thatch to reduce chances of an attic fire setting thatch alight.
- smoke alarms everywhere. This is pretty standard anyway no matter what
the roof.
- no timber stricures are allowed closer than I think 20mm to teh
stacks. In my case we used supalux board spacers and metal hangers to
carry the ridge to stack loads.
- all flues must be lined with ceramic flue liners or steel insulated
liners.
- some fairly srong regs on use of e.g. ceiling mounted spots under
thatched rooves. Mine are actually under fully boarded attic floors.


Pretty rigorous.


That takes care of most of the normal mechanisms. The one remaining
poetntial problem is a chimney fire, which can indeed eject huge
quantities of burning material. In normal use the flue gases cool down
fast as they rise up teh chimney, and no burning material is carried up.

Chimney fires are all about dirt flues and burning too hot. If you get
one, you puit teh fire out below immediately with buckest of water, and
block teh flue to starve the oxygen. It goes out n a few seconds. Its
very unlikely that it would hurt damp wet thatch, but I have a hose
always connected outside anyway.

That was one thing that I was thinking about, and should be avoidable
with proper sweeping of the chimney anyway.

I was thinking more in terms of log fires and during lighting with
paper etc. where small pieces of burning material can go up the flue,
or do you feel that they should have cooled sufficiently by the time
they have gone up the flue and potentially blown across and fallen
onto the roof? Presumably all this is OK or there would be many
more fires. I can appreciate that the greater danger is from
within.




..andy

To email, substitute .nospam with .gl

The Natural Philosopher wrote in message ...
Rick Dipper wrote:

I had this issue, the opening was too tall, the local fire shop sole me a
small "hood" to fit in the top or the opening.



Ok, I hjad this problem in SPADES when the dumb builder built my
inglenooks.

There is a page on the web that I discovered that covers this all in
detail.

There are a few salient points you need to know.

The most important is that the fire APERTURE - if you like the area
bounded by the grate, the sides of the fire and the lintel over teh top
of it should be no more than 5, or at most 7 times the cross sectional
area of the flue. Any more than this and the velocity of air being drawn
into the fire will not be enough to suck stray smoke into the fire etc etc.

I'm not disagreeing with this comment, but it is possible to work with
aperture ratios approaching 14 if the entry to the chimney is funnelled.
Most standard fire places use an angled restictor throat at the entry to the
chimney, to produce a pressure change which aids gas flow. Sorry, I can't
remember all the details, perhaps someone else can enlighten us. When I
researched the problem of building fireplaces, I found that all the
experienced fireplace experts, said "Try it and see if it works!, but allow
for a fanned flue if it doesn't!!"
I'd agree however that some form of a reduction in aperture is probably the
easiest solution. It's probably worth asking a few questions of an
experienced fireplace showroom, they may have an off the shelf solution for
a few pounds.
Regards
Capitol

Thanks for all the responses - lots to chew on there (and I'm now very
pleased I don't have a thatched roof).

Looking in more details at the fireplace, my clay pipe is about 10" by
7" - ie. area roughly 70 sq in. My fireplace area (w x d) is 23" x 14"
or 322 sq in. therefore my ratio of areas is 322/70 or 4.6, so should
be well within the accepted practice referred to above. It is off
centre (about 3" from right side, 10" from left) which may be a
factor. The angled piece seems to run up at about 45 degrees.

To answer some of the other questions posed above. At the top of the
chimney is a conventional chimney pot - not capped. The smoke is not
flooding out, but rather just leaking out slowly into the room from
the hearth. I'm going to try a selection of the ideas above later
(when i;m feeling brave).

Does anyone know of any sources on line for cowls to go in the
fireplace.

Thanks again for all the ideas.

TP

Andy Hall wrote:


Chimney fires are all about dirt flues and burning too hot. If you get
one, you puit teh fire out below immediately with buckest of water, and
block teh flue to starve the oxygen. It goes out n a few seconds. Its
very unlikely that it would hurt damp wet thatch, but I have a hose
always connected outside anyway.


That was one thing that I was thinking about, and should be avoidable
with proper sweeping of the chimney anyway.

I was thinking more in terms of log fires and during lighting with
paper etc. where small pieces of burning material can go up the flue,
or do you feel that they should have cooled sufficiently by the time
they have gone up the flue and potentially blown across and fallen
onto the roof? Presumably all this is OK or there would be many
more fires. I can appreciate that the greater danger is from
within.


The flues are pretty tall. Mine is, on a storey-and-half house, 9 meters
from grate to the pot from memory. Being fairly large fires as well
they don't draw to a roar easily. I have set coal flues alight -
usually by getting a good roar going when starting using
hardboard/cardboard etc. Even these rarely carry burning stuff all the
way up tho - only time I have EVER seen the top spouting red hot stuff
is in a flue fire. Everyone should start one just for the experience :-)

And if its that hot, it gets carried well clear anyway.

Basically, the regs have got it about rigfht IMHO. You have to work
pretty hard to have a problem with open fires that are designed to regs
these days, and swept properly.







.andy

To email, substitute .nospam with .gl

Capitol wrote:

The Natural Philosopher wrote in message ...

Rick Dipper wrote:


I had this issue, the opening was too tall, the local fire shop sole me a

small "hood" to fit in the top or the opening.


Ok, I hjad this problem in SPADES when the dumb builder built my

inglenooks.

There is a page on the web that I discovered that covers this all in

detail.

There are a few salient points you need to know.

The most important is that the fire APERTURE - if you like the area
bounded by the grate, the sides of the fire and the lintel over teh top
of it should be no more than 5, or at most 7 times the cross sectional
area of the flue. Any more than this and the velocity of air being drawn
into the fire will not be enough to suck stray smoke into the fire etc etc.


I'm not disagreeing with this comment, but it is possible to work with
aperture ratios approaching 14 if the entry to the chimney is funnelled.


I would agree with that to the extent that muy smike hoods are running
on estimated 10:1 ratio and work fairly well. They don't 'draw' like a
coal fire throtled down does though. I suspect my 5-7:1 was a ratio for
open hearh coal that needs a better draught.


Most standard fire places use an angled restictor throat at the entry to the
chimney, to produce a pressure change which aids gas flow. Sorry, I can't
remember all the details, perhaps someone else can enlighten us. When I
researched the problem of building fireplaces, I found that all the
experienced fireplace experts, said "Try it and see if it works!, but allow
for a fanned flue if it doesn't!!"


Those are hopeless. The noise is incredible. They are the open fire
equivalent to Saniflo.


I'd agree however that some form of a reduction in aperture is probably the
easiest solution. It's probably worth asking a few questions of an
experienced fireplace showroom, they may have an off the shelf solution for
a few pounds.


Few hundred pounds. They know bugger all as well, I tried. In fact I am
probably the nearest thing to an expert that exists. And I know next to
bugger all. You can get pre-desined coal fireplaces that will sork whjen
slotted into standard flues, but no one build wod burning firepalces any
more. After a struggle, mine are beginning to perform well - not just
adequately, but well - and the experience is as I summarised.

The key is reducing fireplace aperture by raising the grate, or fitting
a smoke hood.

Insofar as smoking is concerned. You can fine tune that by throttling
the flue in a smooth choke type design, that accelerates airflow around
the aperture top, but too much throttling will reduce flow rates too much.




Regards
Capitol

Tim Pollard wrote:

Thanks for all the responses - lots to chew on there (and I'm now very
pleased I don't have a thatched roof).

Looking in more details at the fireplace, my clay pipe is about 10" by
7" - ie. area roughly 70 sq in. My fireplace area (w x d) is 23" x 14"
or 322 sq in. therefore my ratio of areas is 322/70 or 4.6, so should
be well within the accepted practice referred to above. It is off
centre (about 3" from right side, 10" from left) which may be a
factor. The angled piece seems to run up at about 45 degrees.

To answer some of the other questions posed above. At the top of the
chimney is a conventional chimney pot - not capped. The smoke is not
flooding out, but rather just leaking out slowly into the room from
the hearth. I'm going to try a selection of the ideas above later
(when i;m feeling brave).

Does anyone know of any sources on line for cowls to go in the
fireplace.



These are nearly all custome made.

In your case a simple flap of bent stell that screws up into teh top of
teh hearth a cpoup[le of inches back from the mantle piece and comes
down a few inches at an angle towrds the front of the fire should
suffice. I suspect the problem is more that you have (as I did) a 'flat
top with a hole in it' rather than a carefully blended reducing
fire-to-flue design...ou shold attempt to recreate that.





Thanks again for all the ideas.

TP

Hi,

sorry for the late reply - Google managed to lose my last reply.
I found the following site very useful when I did my fireplace -

http://hearth.com/what/chimneysize.html

I think one of your biggest problems is possibly the shallow angle of
the new piece of flue.

Let us know how you get on - I for one am very interested.

Alan.

(Tim Pollard) wrote in message . com...
Hello

I am new to this group but I'm hoping some fireplace expert can point
me in the right direction with a solution to a problem with my new
fireplace.

I recently extended my living room which would have resulted in my
existing fireplace being off centre. To solve this, my builders
blocked up the old fireplace and made a new opening in the new centre
of the wall, joining this to the existing chimney about 2 metres up.
The chimney is a 30s unlined one. The connection beteween fireplace
and chimney is by a clay flue pipe. The displacement (ie. amount the
fireplace was moved) is about 1.25m.

Now the old fireplace drew perfectly - except it was a 70s built rough
stone horror (just like my granny had in her bungalow built in 1972).
The new one has only been used once, but a small proportion of the
smoke 'leaked out' into the room, making its use a bit untenable! It
wasn't enough to suggest that the chimney was blocked, but rather that
the chimney wasn't drawing as well as it had.

I suspect that the problem comes from a number of factors:

- The opening is taller than it was, so there is a bigger gap between
grate and flue. The builders made a brick insert in the shape of a
gothic arch, 85cm high by 58 wide, 35 deep. The old opening was lower
- around 70cm, I think.

- The clay pipe is roughly 25cm x 25cm, which I suspect is less than
the old one (but I have to be honest and admit that I never did stick
my head up the old opening).

- There is now a bend in the flue which (maybe) reduces the draw
efficiency.

Can anyone tell me what is likely to be the problem and how I should
solve it? I had wondered whether buying a hood to reduce the distance
between the fire and the effective top of the opening would help? If
so, does anyone know where I can get one in the South London (Croydon)
area?

When I'm feeling brave I intend to try putting the grate up on bricks,
to see if raising it closer to the top of the opening will improve
things. Sensible or just a license to smoke some people?!

Any other ideas would be most welcome!

Tim P

(Tim Pollard) wrote in message om...
Thanks for all the responses - lots to chew on there (and I'm now very
pleased I don't have a thatched roof).

Looking in more details at the fireplace, my clay pipe is about 10" by
7" - ie. area roughly 70 sq in. My fireplace area (w x d) is 23" x 14"
or 322 sq in. therefore my ratio of areas is 322/70 or 4.6, so should
be well within the accepted practice referred to above. It is off
centre (about 3" from right side, 10" from left) which may be a
factor. The angled piece seems to run up at about 45 degrees.

To answer some of the other questions posed above. At the top of the
chimney is a conventional chimney pot - not capped. The smoke is not
flooding out, but rather just leaking out slowly into the room from
the hearth. I'm going to try a selection of the ideas above later
(when i;m feeling brave).

Does anyone know of any sources on line for cowls to go in the
fireplace.

Thanks again for all the ideas.

TP

Have a think about getting one of these;
http://www.flamewavefires.co.uk/tortoise_overview.html

I am planning on getting one of these very soon. It solves all the
problems of sizing etc. I also like them because they have a lifetime
garauntee which means i will keep it from one house to the next.

They aint cheap though.. The size i want is around £850.