Boiler removed so that branch is redundant, living room fireplace now
bricked up so the remaining branch is also redundant.

Do I need to cap the chimney or can I simply leave it?

TIA

--
Frank
(Beware of spam trap - remove the negative)

"F" wrote in message
...
Boiler removed so that branch is redundant, living room fireplace now
bricked up so the remaining branch is also redundant.

Do I need to cap the chimney or can I simply leave it?

TIA


You really need to have an airflow through the whole stack, so long as you
have an airbrick at the bottom it is not necessary to cap it. Whatever rain
ends up in there will quickly dry out. The ideal though is to cap it with a
rain shielding device that lets air out, usually this is a mushroom pot.,
though other methods are equally valid such as a ridge tile leaving the ends
open. You really should have the vent at the bottom whatever though.

--
Mike w

On Jun 1, 11:49 pm, "visionset" wrote:
"F" wrote in message

...

Boiler removed so that branch is redundant, living room fireplace now
bricked up so the remaining branch is also redundant.

Do I need to cap the chimney or can I simply leave it?

TIA

You really need to have an airflow through the whole stack, so long as you
have an airbrick at the bottom it is not necessary to cap it. Whatever rain
ends up in there will quickly dry out. The ideal though is to cap it with a
rain shielding device that lets air out, usually this is a mushroom pot.,
though other methods are equally valid such as a ridge tile leaving the ends
open. You really should have the vent at the bottom whatever though.

--
Mike w

Hi
Slightly different question, why do you need an airflow? Surely it
becomes just like a cavity wall -which in my last house (50years old)
did not appear to be vented?
Al

In article . com,
al writes:

Hi
Slightly different question, why do you need an airflow? Surely it
becomes just like a cavity wall -which in my last house (50years old)
did not appear to be vented?

Chimneys are constructed to be airtight. Any moisture which
gets in (typically through parts which are single skin walls)
gets trapped, and moisture gradually builds up inside.
I opened one out which had been sealed for 20 years (had a
vent at bottom but not at the top), and it was soaking wet
with condensation running down the flue. It had soaked the
whole chminey breast, but this wasn't very visible inside
as it had caused the plaster to all come away from the wall
and hang in mid-air, creating a moisture break. (Once I
realised, one thump with a hammer and all the plaster came
crashing down.) It took 3 months to dry out the chimney
breast once the bottom and top were vented, before I could
replaster it and finish off the decorating.

BTW, if the chimney is on an outside wall and you are
going to be bricking up the fireplace, provide the bottom
ventilation from the outside rather than the room, as this
will lose you less room heat up the chimney. When I did
mine, I actually blocked the flue off at the top of the
fireplace (piece of plasterboard with loft insulation on
top), and vented above that to the outside. Then I am left
with the fireplace alcove open to the room, which can be
used decoratively or for storage. The rear, being a half
brick wall, I lined with cellotex to prevent it forming a
cold spot and condensation. I dropped a lighting wire
down the flue from the loft to allow a hidden light to be
fitted in the alcove, which gives a very nice effect.

I don't think cavity walls normally have anything blocking
off the top, and they aren't built to be airtight -- often
the odd perp (vertical pointing) allows air through.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On Jun 2, 12:10 pm, (Andrew Gabriel)
wrote:
In article . com,
al writes:



Hi
Slightly different question, why do you need an airflow? Surely it
becomes just like a cavity wall -which in my last house (50years old)
did not appear to be vented?

Chimneys are constructed to be airtight. Any moisture which
gets in (typically through parts which are single skin walls)
gets trapped, and moisture gradually builds up inside.
I opened one out which had been sealed for 20 years (had a
vent at bottom but not at the top), and it was soaking wet
with condensation running down the flue. It had soaked the
whole chminey breast, but this wasn't very visible inside
as it had caused the plaster to all come away from the wall
and hang in mid-air, creating a moisture break. (Once I
realised, one thump with a hammer and all the plaster came
crashing down.) It took 3 months to dry out the chimney
breast once the bottom and top were vented, before I could
replaster it and finish off the decorating.

snip

I don't think cavity walls normally have anything blocking
off the top, and they aren't built to be airtight -- often
the odd perp (vertical pointing) allows air through.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

Thanks Andrew.
Al

On 01/06/2007 23:49 visionset wrote:

You really should have the vent at the bottom whatever though.

Pity, that's what I really wanted to avoid as it would spoil a fairly
large expanse of flat wall...

--
Frank
(Beware of spam trap - remove the negative)

On 02/06/2007 12:10 Andrew Gabriel wrote:

I opened one out which had been sealed for 20 years (had a
vent at bottom but not at the top), and it was soaking wet
with condensation running down the flue.

I really want to avoid a vent on the wall in the room (the chimney is on
an inside wall). Could I get away with simply not capping it?

--
Frank
(Beware of spam trap - remove the negative)

In article ,
F writes:
I really want to avoid a vent on the wall in the room (the chimney is on
an inside wall). Could I get away with simply not capping it?

No you can't.
Have you got a sub floor space you could vent it to?
What does the fireplace back onto?

I suppose in theory, if you capped the top against rain but vented
it, and there's not much exposed stack above the roof, you might
just get away with it, but then again, you might not.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]

On 03/06/2007 19:07 Andrew Gabriel wrote:

Have you got a sub floor space you could vent it to?

It's sitting on a concrete slab.
What does the fireplace back onto?

Another room.

Looks like I'm stuck with a vent. Is there a minimum size?

--
Frank
(Beware of spam trap - remove the negative)

"F" wrote in message
...
On 03/06/2007 19:07 Andrew Gabriel wrote:

Have you got a sub floor space you could vent it to?

It's sitting on a concrete slab.
What does the fireplace back onto?

Another room.

Looks like I'm stuck with a vent. Is there a minimum size?


You mean available sizes or regs?

Anything will drastically improve things.
To a certain extent it won't matter much, small vents will have a faster
flow and make up for their smaller size - to a certain extent! So long as
there is flow top to bottom I doubt you will have a problem - you would
probably get away with as little as 25cm² You can get proprietory brass
grilles at that size - 5x5cm.

--
Mike W

In article ,
"visionset" writes:

"F" wrote in message
...
On 03/06/2007 19:07 Andrew Gabriel wrote:

Looks like I'm stuck with a vent. Is there a minimum size?


You mean available sizes or regs?

Anything will drastically improve things.
To a certain extent it won't matter much, small vents will have a faster
flow and make up for their smaller size - to a certain extent! So long as
there is flow top to bottom I doubt you will have a problem - you would
probably get away with as little as 25cm² You can get proprietory brass
grilles at that size - 5x5cm.

The top vent on mine is half a brick taken out (with wire mesh to
prevent animal entry). It's in the loft just below the roof line
as I had no external access at the time, although it would have
been better nearer the top of the exposed chimney.
The bottom is a whole air brick to the outside as it was easier.

--
Andrew Gabriel
[email address is not usable -- followup in the newsgroup]