We've got an old chimney in our kitchen. The bottom has been removed,
and the stack is held up on an RSJ. It's lined with what look like
ceramic drain pipes. At the top used to be a cowl, but as it looked
horrible (and doubtless sucked lots of heat out) I replaced it with a
cap which has a much smaller opening. At the bottom is a hit-and-miss
grill. We've tried the grill both open and shut - and we're suffering
from condensation dripping down onto the worktop beneath. It's much
worse without the cowl

It's worse after rain. This may just be due to higher humidity, or it
could be soaking in - the pointing isn't wonderful.

What should we do?

Andy

On 19/01/16 21:59, Vir Campestris wrote:
We've got an old chimney in our kitchen. The bottom has been removed,
and the stack is held up on an RSJ. It's lined with what look like
ceramic drain pipes. At the top used to be a cowl, but as it looked
horrible (and doubtless sucked lots of heat out) I replaced it with a
cap which has a much smaller opening. At the bottom is a hit-and-miss
grill. We've tried the grill both open and shut - and we're suffering
from condensation dripping down onto the worktop beneath. It's much
worse without the cowl

It's worse after rain. This may just be due to higher humidity, or it
could be soaking in - the pointing isn't wonderful.

What should we do?

Andy

Is the chimney capped off at the top (to allow ventilation but prohibit
rain entering directly)?

Next thing that might be worth a shot is painting water repellent on the
bricks above the roof line (I did with one defunct stack).

Or putting a drain in to the outside and blocking up the vent in the
kitchen?
Brian

"Tim Watts" wrote in message
...
On 19/01/16 21:59, Vir Campestris wrote:
We've got an old chimney in our kitchen. The bottom has been removed,
and the stack is held up on an RSJ. It's lined with what look like
ceramic drain pipes. At the top used to be a cowl, but as it looked
horrible (and doubtless sucked lots of heat out) I replaced it with a
cap which has a much smaller opening. At the bottom is a hit-and-miss
grill. We've tried the grill both open and shut - and we're suffering
from condensation dripping down onto the worktop beneath. It's much
worse without the cowl

It's worse after rain. This may just be due to higher humidity, or it
could be soaking in - the pointing isn't wonderful.

What should we do?

Andy

Is the chimney capped off at the top (to allow ventilation but prohibit
rain entering directly)?

Next thing that might be worth a shot is painting water repellent on the
bricks above the roof line (I did with one defunct stack).

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On 20/01/16 09:59, Brian Gaff wrote:
Or putting a drain in to the outside and blocking up the vent in the
kitchen?
Brian

That's a really good idea!

If the stack is on the outside wall, put an external vent in and close
it off completely inside.

On 20/01/2016 09:59, Brian Gaff wrote:
Or putting a drain in to the outside and blocking up the vent in the
kitchen?
Brian

"Tim Watts" wrote in message
...
On 19/01/16 21:59, Vir Campestris wrote:
We've got an old chimney in our kitchen. The bottom has been removed,
and the stack is held up on an RSJ. It's lined with what look like
ceramic drain pipes. At the top used to be a cowl, but as it looked
horrible (and doubtless sucked lots of heat out) I replaced it with a
cap which has a much smaller opening. At the bottom is a hit-and-miss
grill. We've tried the grill both open and shut - and we're suffering
from condensation dripping down onto the worktop beneath. It's much
worse without the cowl

It's worse after rain. This may just be due to higher humidity, or it
could be soaking in - the pointing isn't wonderful.

What should we do?

Andy

Is the chimney capped off at the top (to allow ventilation but
prohibit rain entering directly)?

Next thing that might be worth a shot is painting water repellent on
the bricks above the roof line (I did with one defunct stack).


Or having the stack taken down to roof level, which is a job I'm
resigned to. It's leaking somewhere but not obvious where, and that's a
hell of a lot of re-pointing

OK, answering all at once, inline (Sorry Brian)


On 20/01/2016 11:00, stuart noble wrote:
On 20/01/2016 09:59, Brian Gaff wrote:
Or putting a drain in to the outside and blocking up the vent in the
kitchen?

Sadly the bottom of the outside is inside a roof - part of the kitchen
has a lean-to type roof.

"Tim Watts" wrote in message
...

Is the chimney capped off at the top (to allow ventilation but
prohibit rain entering directly)?

Yes, I did mention that - it used to have a cowl, but now has a cap.

Next thing that might be worth a shot is painting water repellent on
the bricks above the roof line (I did with one defunct stack).


That had crossed my mind. I'll attack the pointing and paint something
on it next summer.


Or having the stack taken down to roof level, which is a job I'm
resigned to. It's leaking somewhere but not obvious where, and that's a
hell of a lot of re-pointing

We're listed. They were difficult about us having a new chimney pot on
the other one; they'd never allow that. (The new pot was to keep the
heat from the wood burner well away from the thatch, which the insurance
co. wanted)

Andy

On 20/01/16 21:16, Vir Campestris wrote:

We're listed. They were difficult about us having a new chimney pot on
the other one; they'd never allow that. (The new pot was to keep the
heat from the wood burner well away from the thatch, which the insurance
co. wanted)

Andy

Isn't that just totally insane...

On Tuesday, January 19, 2016 at 9:59:40 PM UTC, Vir Campestris wrote:
We've got an old chimney in our kitchen. The bottom has been removed,


ventilation must be with a hole top and bottom so it works, or warm moist air will condense inside and rot the brickwork. But the bottom ventilation lets lots of warm moist air into the chimney.

The only solution I can think of is to fill the air gap with concrete or kingspan and foam, firefoam not flammable foam. Then air wont infiltrate and condense. Concrete might be too heavy!

[george]

but if its listed they maybe wont let you pour concrete or foam down the chimney as thats not irreversible.

So maybe get the chimney lined properly?
or diy from inside
and use it as part of a new improved
kitchen ventilation system?
Maybe blocking an existing out-vent when this is working?

[george]

On 21/01/2016 19:24, DICEGEORGE wrote:
but if its listed they maybe wont let you pour concrete or foam down the chimney as thats not irreversible.

So maybe get the chimney lined properly?
or diy from inside
and use it as part of a new improved
kitchen ventilation system?
Maybe blocking an existing out-vent when this is working?

[george]

I'd be cautious about pouring _anything_ down it, when there's only
plastic grill stopping anything from ending up in the kitchen...

We're considering a new kitchen. Putting a sleeve in it and using it for
the cooker hood is one possibility - with the risk that we'd get
condensation inside the sleeve instead...

Andy

can you drill out a few bricks in the attic into the chimney for inspection?

(and maybe eventual use in air ventilation system)

On Tue, 19 Jan 2016 21:59:41 +0000, Vir Campestris wrote:

We've got an old chimney in our kitchen. The bottom has been removed,
and the stack is held up on an RSJ. It's lined with what look like
ceramic drain pipes. At the top used to be a cowl, but as it looked
horrible (and doubtless sucked lots of heat out) I replaced it with a
cap which has a much smaller opening. At the bottom is a hit-and-miss
grill. We've tried the grill both open and shut - and we're suffering
from condensation dripping down onto the worktop beneath. It's much
worse without the cowl

It's worse after rain. This may just be due to higher humidity, or it
could be soaking in - the pointing isn't wonderful.

What should we do?

Andy

Lack of airflow up the chimney?
Worse after replacing the cowl seems to confirm this.
There has to be enough flow of dry(ish) warm(ish) air to absorb any
moisture within the chimney and then carry it to the outside through the
top vent.
So perhaps a ventilation fan to push air up the chimney and/or replace the
original cowl as that seemed to be doing the job better than the current
arrangement.

From information within this thread, getting a good external airflow into
the chimney doesn't seem to be an easy option so to combat the damp you
probably need to accept that you will have to lose some heat to shift it.

There have been loads of posts about tenants and damp houses, almost all
due to the tenants closing all the windows to keep the heat in and thus
trapping all the moisture as well. Ventilation (in moderation) is a very
good thing but does involve some heat loss.

Cheers

Dave R


--
Windows 8.1 on PCSpecialist box

On 24/01/2016 13:35, David wrote:
Lack of airflow up the chimney?
Worse after replacing the cowl seems to confirm this.
There has to be enough flow of dry(ish) warm(ish) air to absorb any
moisture within the chimney and then carry it to the outside through the
top vent.
So perhaps a ventilation fan to push air up the chimney and/or replace the
original cowl as that seemed to be doing the job better than the current
arrangement.

From information within this thread, getting a good external airflow into
the chimney doesn't seem to be an easy option so to combat the damp you
probably need to accept that you will have to lose some heat to shift it.

There have been loads of posts about tenants and damp houses, almost all
due to the tenants closing all the windows to keep the heat in and thus
trapping all the moisture as well. Ventilation (in moderation) is a very
good thing but does involve some heat loss.

One of the possibles is to route an extract from the cooker hood up there.

Of course that would be warm, but not dry.

Andy