My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?

On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


Your cavity walls ARE insulated. Tell the salesman to EFF OFF.

On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

At that vintage, chances are they are full fill with solid insulation
batts. So there will be no space for additional injected insulation.


--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

On Tuesday, 18 February 2020 19:36:57 UTC, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?

The trouble with cavity wall bats is that their effectiveness is entirely dependent on how carefully they were fitted when the house was constructed.

The only way you can tell if there are gaps is by use of an infrared camera.
(You have to wait for cold weather, turn the house heating up, go outside and search for hot spots after a bout 12 hours). Or you can search for cold spots from inside. Some tool hire places have IR cameras. It's very enlightening,

The camera can detect "hot" footprints when you walk across a carpet!!!

At one time you could get IR film for ordinary cameras but we've now gone digital.

You can drill a hole in the wall in an inconspicuous place to see what insulation you have. Or you might be able to see in the loft with a torch and a mirror.

There is/was a grant for insulation at one time. Dunno what the current position is.

How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new house?
grin.
Brian

--
----- --
This newsgroup posting comes to you directly from...
The Sofa of Brian Gaff...

Blind user, so no pictures please
Note this Signature is meaningless.!
"Andrew" wrote in message
...
On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


Your cavity walls ARE insulated. Tell the salesman to EFF OFF.

John Not.responding.@dotcom wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


We had a phone call the other day about insulation- I think loft insulation
in this case, my wife answered the phone but the caller hung up when she
suggested he spoke to me. He claimed there were grants available etc.

I was suspicious- firstly the call was to her mobile, why hang up, and
grants tend to be limited to certain groups ( none of which we fit into).

Being curious, I did a search. Sure enough, grants are available for loft
insulation but only in limited circumstances ( which certainly dont apply
to us).

It seems there are companies offering to install insulation, claiming
grants are available and to try and secure one for you by completing forms
etc. However, they dont mention to be eligible you need to meet certain
criteria AND there seems to be a finite allocation (presumably each year)
which is allocated on a first come first serve basis.

Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new house?
grin.
Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

On Tue, 18 Feb 2020 23:40:49 -0800 (PST), harry wrote:

On Tuesday, 18 February 2020 19:36:57 UTC, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

Any views?

The trouble with cavity wall bats is that their effectiveness is entirely dependent on how carefully they were fitted when the house was constructed.

The only way you can tell if there are gaps is by use of an infrared camera.
(You have to wait for cold weather, turn the house heating up, go outside and search for hot spots after a bout 12 hours). Or you can search for cold spots from inside. Some tool hire places have IR cameras. It's very enlightening,

The camera can detect "hot" footprints when you walk across a carpet!!!

At one time you could get IR film for ordinary cameras but we've now gone digital.

You can drill a hole in the wall in an inconspicuous place to see what insulation you have. Or you might be able to see in the loft with a torch and a mirror.

There is/was a grant for insulation at one time. Dunno what the current position is.

Is there such a thing as an infrared filter for a digital camera? If so, the
LCD should show the image same as a dedicated camera does.
--
Peter.
The gods will stay away
whilst religions hold sway

On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?

no

On 19/02/2020 01:23, John Rumm wrote:
On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

At that vintage, chances are they are full fill with solid insulation
batts. So there will be no space for additional injected insulation.


if they are full they will be the type of batts with vertical
stratification to stop water ingress so don't mess with them ...

On 19/02/2020 08:35, PeterC wrote:
On Tue, 18 Feb 2020 23:40:49 -0800 (PST), harry wrote:

On Tuesday, 18 February 2020 19:36:57 UTC, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

The only way you can tell if there are gaps is by use of an infrared camera.
[snip]

There is/was a grant for insulation at one time. Dunno what the current position is.

Is there such a thing as an infrared filter for a digital camera? If so, the
LCD should show the image same as a dedicated camera does.

Wrong waveband.

Near infrared is just off the end of the visible spectrum at 750-1000nm.
You can get IR pass filters but they mainly make trees look white.

Thermal infrared characteristic of objects at ambient temperatures on
Earth is in the 10um band with an order of magnitude longer wavelength.
You need special detectors and typically germanium lenses to make images
in thermal band IR. You can buy add-ons for mobile phones to do a crude
thermal IR camera for not that much (or hire real gear for a price):

https://www.amazon.co.uk/Thermal-Res...dp/B0728C7KND/

I think there is an Android one too. Don't expect too much as the sensor
is only 80x60 pixels interpolated up.

--
Regards,
Martin Brown

On 19/02/2020 08:21, Brian Reay wrote:
John Not.responding.@dotcom wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


We had a phone call the other day about insulation- I think loft insulation
in this case, my wife answered the phone but the caller hung up when she
suggested he spoke to me. He claimed there were grants available etc.

I was suspicious- firstly the call was to her mobile, why hang up, and
grants tend to be limited to certain groups ( none of which we fit into).

Being curious, I did a search. Sure enough, grants are available for loft
insulation but only in limited circumstances ( which certainly dont apply
to us).

It seems there are companies offering to install insulation, claiming
grants are available and to try and secure one for you by completing forms
etc. However, they dont mention to be eligible you need to meet certain
criteria AND there seems to be a finite allocation (presumably each year)
which is allocated on a first come first serve basis.



you have to jump through hoops to get any grants these days...ridiculous
thickness of loft insulation wall insulation usually external and an
upgraded boiler I tell them to naff off......in the 70's the we usecd to
give loft insulation grants only where there was NONE ...much more
sensible.....

On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new house?
grin.
Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 19/02/2020 07:40, harry wrote:


At one time you could get IR film for ordinary cameras but we've now gone digital.

Different IR band to the cameras designed to detect heat loss, and you
can still make a digital camera into an IR camera. The IR band used to
detect heat loss, say, from a house is blocked by glass so the glass
lenses used in a conventional camera would stop their use for this
application in either a (modified) digital camera or a film camera.

The sensors in digital cameras/phones can see IR up to around 1.1um
although most may have a filter to exclude some or all of the near IR
band. Point your phone camera at the output of your TV remote and press
any button and maybe you will see the IR LED flashing. Iphones may have
a IR filter on the back camera but possibly not on the front camera.

Military IR cameras and those commonly becoming available for industrial
or consumer applications operate in the 3um to 5um band or the 8 to
12/14um band. Cameras fitted to the police helicopters are probably the
latter. These cameras most probably have Germanium lenses. To keep costs
low (to perhaps a couple of hundred quid) consumer IR cameras may be
limited to 64x64 or 100x100 true pixel sensors and have small "slow"
wide angle lenses and low video frame rates.

A £400 IR camera attachment with a 160 x 120 pixel sensor.
https://www.youtube.com/watch?v=Oiv7sEXL1cI

IR has no colour hence a native B&W video output. This video output is
usually modified to give a false colour output. Everything light grey to
white is rendered white, yellow or red and everything dark grey is
rendered black or blue. The grey scale in between is assigned different
colours. Many different false colour schemes schemes can be used.

If you have an old digital camera and you want to experiment with near
IR (the effect you could obtain with IR film)
https://www.instructables.com/id/inf...-the-real-way/

or

https://tinyurl.com/wdu4oey

Try it on a very cheap web cam.

If you have any processed colour film negatives around the bits at the
end that are completely black can be used as the filter instead of of
the Congo Blue filters mentioned in the above article. You could use two
bits(double thickness) of this black negative as a stronger filter.


--




It depends on the IR band

Remote controls are in the near IR band up to 1.1 um and can been seen
through a glass lens of a digital camera.

PIR detectors operate in the 8 to 14 um IR band. Most glass is usually
opaque in this band. However the sun shining through the window can heat
the net curtains and passing clouds cause a change in this temperature
triggering the PIR.

Once you go outside of the visible band it may be hard to predict what
may be causing a PIR to trigger. I used to work with and design military
grade IR cameras. A matt varnish on a wood surface could act as a
perfect mirror in IR and items such as black plastic rubbish sacks are
completely transparent.


You can drill a hole in the wall in an inconspicuous place to see what insulation you have. Or you might be able to see in the loft with a torch and a mirror.

There is/was a grant for insulation at one time. Dunno what the current position is.










--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On 19/02/2020 08:21, Brian Reay wrote:


It seems there are companies offering to install insulation, claiming
grants are available and to try and secure one for you by completing forms
etc. However, they dont mention to be eligible you need to meet certain
criteria AND there seems to be a finite allocation (presumably each year)
which is allocated on a first come first serve basis.


And probably from a company that you wouldn't want to employ if you had
to pay for it! These cold caller types appear to be in the same league
as those with some left over tarmac for your driveway.


--
mailto : news {at} admac {dot} myzen {dot} co {dot} uk

On Wednesday, 19 February 2020 08:35:48 UTC, PeterC wrote:
On Tue, 18 Feb 2020 23:40:49 -0800 (PST), harry wrote:

On Tuesday, 18 February 2020 19:36:57 UTC, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

Any views?

The trouble with cavity wall bats is that their effectiveness is entirely dependent on how carefully they were fitted when the house was constructed.

The only way you can tell if there are gaps is by use of an infrared camera.
(You have to wait for cold weather, turn the house heating up, go outside and search for hot spots after a bout 12 hours). Or you can search for cold spots from inside. Some tool hire places have IR cameras. It's very enlightening,

The camera can detect "hot" footprints when you walk across a carpet!!!

At one time you could get IR film for ordinary cameras but we've now gone digital.

You can drill a hole in the wall in an inconspicuous place to see what insulation you have. Or you might be able to see in the loft with a torch and a mirror.

There is/was a grant for insulation at one time. Dunno what the current position is.

Is there such a thing as an infrared filter for a digital camera? If so, the
LCD should show the image same as a dedicated camera does.


I have some IR pix of my house. Taken from the inside on a cold day so you can see the cold spots..
They are astonishing.
I have 600mm insulation my house but there were air leaks. (and cold water pipes)

On 19/02/2020 09:36, alan_m wrote:
On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
Â* I have no cavity walls, but still get leaflets through the door
about it
and wonder at the waste ofÂ* rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new
house?
Â* grin.
Â* Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?



Full-fill cavity wall insulation needs a modicum of care on the part
of the brickies, to avoid creating a cement bridge across the top of
a batt before the next rows of blocks + bricks are built and also
(more importantly) to avoid dropping mortar onto the top of the
installed batt before the next row of batts is pushed down into
the cavity.

A 4 inch cavity, with rockwool full fill batts should have the
same U vaalue as a 4 inch cavity with 2 inch celotex clamped to
the inner leaf, leaving a 2 inch ventilated cavity, but the
celotex must be tightly fitted, and clamped to the inner leaf
using purpose-made plastic 'wheels' that clip over the wall ties.
Ideally, the joints should be taped with aluminium tape too.

I've seen some awful new builds near me, built after 2009 where
slabs of inch thick expanded poly were just chucked insde the cavity
allowed air flow each side of the insulation , rendering it useless.

On 19/02/2020 08:43, Jim GM4DHJ ... wrote:
On 19/02/2020 01:23, John Rumm wrote:
On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

At that vintage, chances are they are full fill with solid insulation
batts. So there will be no space for additional injected insulation.


if they are full they will be the type of batts with vertical
stratification to stop water ingress so don't mess with them ...

Those batts are treated with something to make them water repellent.
STill a valid construction method I believe for properties
not in those parts subjected to heavy driving rain.

On 19/02/2020 08:21, Brian Reay wrote:
John Not.responding.@dotcom wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


We had a phone call the other day about insulation- I think loft insulation
in this case, my wife answered the phone but the caller hung up when she
suggested he spoke to me. He claimed there were grants available etc.

I was suspicious- firstly the call was to her mobile, why hang up, and
grants tend to be limited to certain groups ( none of which we fit into).

Being curious, I did a search. Sure enough, grants are available for loft
insulation but only in limited circumstances ( which certainly dont apply
to us).

It seems there are companies offering to install insulation, claiming
grants are available and to try and secure one for you by completing forms
etc. However, they dont mention to be eligible you need to meet certain
criteria AND there seems to be a finite allocation (presumably each year)
which is allocated on a first come first serve basis.




Just tell them your house is a 1930's art-deco house with a flat roof.

On 19/02/2020 12:26, Andrew wrote:
On 19/02/2020 08:21, Brian Reay wrote:
John Not.responding.@dotcom wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


We had a phone call the other day about insulation- I think loft
insulation
in this case, my wife answered the phone but the caller hung up when she
suggested he spoke to me. He claimed there were grants available etc.

I was suspicious- firstly the call was to her mobile, why hang up, and
grants tend to be limited to certain groups ( none of which we fit into).

Being curious, I did a search. Sure enough, grants are available for loft
insulation but only in limited circumstances ( which certainly dont
apply
to us).

It seems there are companies offering to install insulation, claiming
grants are available and to try and secure one for you by completing
forms
etc. However, they dont mention to be eligible you need to meet certain
criteria AND there seems to be a finite allocation (presumably each year)
which is allocated on a first come first serve basis.




Just tell them your house is a 1930's art-deco house with a flat roof.
invite them in and listen to the sales blurb for hours then tell them
you are just a tenant...tee hee

On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.


Any views?


You may do more harm than good by adding foam insulation to rockwool
slab insulation as there is a danger of bridging the cavity which could
cause damp problems.

In any event you would are unlikely to significantly improve the u-value
enough to justify the cost of filling with foam.

On Wednesday, 19 February 2020 08:35:48 UTC, PeterC wrote:

Is there such a thing as an infrared filter for a digital camera?

yes, you can remove it to ge a little IR sensitivity.

If so, the
LCD should show the image same as a dedicated camera does.

hardly. IR near to red (ie red hot emitted IR) & room temperature emitted IR are not the same frequency range.


NT

"alan_m" wrote in message
...
On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about
it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new
house?
grin.
Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?

By using an IR camera outside the house in
winter with the house heating turned up full.

alan_m wrote:
On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new house?
grin.
Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?



I suspect they didnt ;-)

On 19/02/2020 09:36, alan_m wrote:
On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
Â* I have no cavity walls, but still get leaflets through the door
about it
and wonder at the waste ofÂ* rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new
house?
Â* grin.
Â* Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?

They drill a number of holes on the mortar lines and put a camera in.

SteveW

On Thu, 20 Feb 2020 02:47:35 +1100, cantankerous trolling geezer Rodent
Speed, the auto-contradicting senile sociopath, blabbered, again:

FLUSH senile asshole's troll****

02:47? LOL So you've been up and trolling for almost ONE HOUR already! Do
yourself (and everyone) a favour and swallow your Nembutal finally!

--
The Natural Philosopher about senile Rot:
"Rod speed is not a Brexiteer. He is an Australian troll and arsehole."
Message-ID:

On 19/02/2020 12:24, Andrew wrote:
On 19/02/2020 08:43, Jim GM4DHJ ... wrote:
On 19/02/2020 01:23, John Rumm wrote:
On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

At that vintage, chances are they are full fill with solid insulation
batts. So there will be no space for additional injected insulation.


if they are full they will be the type of batts with vertical
stratification to stop water ingress so don't mess with them ...

Those batts are treated with something to make them water repellent.
STill a valid construction method I believe for properties
not in those parts subjected to heavy driving rain.
they used them in scotland all the time....me?...I like a cavity....

On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
I have no cavity walls, but still get leaflets through the door about it
and wonder at the waste of rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new house?
grin.
Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.



Oh god no ....

On 19/02/2020 09:36, alan_m wrote:
On 19/02/2020 08:21, Brian Reay wrote:
Brian Gaff \(Sofa 2\) wrote:
How would they get the existing stuff out? That might be an interesting
answer, involving taking the house apart perhaps.
Â* I have no cavity walls, but still get leaflets through the door
about it
and wonder at the waste ofÂ* rain forest and printers costs at delivering
them to houses they cannot fit it to. maybe they will built me a new
house?
Â* grin.
Â* Brian


They dont. If the slab stuff has gaps, they can ( in theory) inject the
foam stuff to fill them. Ive heard of it once, how effective it was/is I
dont know.

How would they establish if the existing cavity wall insulation has gaps?


do you mean gaps which is unlikely with the way the batts are held on to
the inner leaf or just missing???

On 19/02/2020 09:39, alan_m wrote:
On 19/02/2020 07:40, harry wrote:


At one time you could get IR film for ordinary cameras but we've now
gone digital.

Military IR cameras and those commonly becoming available for industrial
or consumer applications operate in the 3um to 5um band or the 8 to
12/14um band. Cameras fitted to the police helicopters are probably the
latter. These cameras most probably have Germanium lenses. To keep costs
low (to perhaps a couple of hundred quid) consumer IR cameras may be
limited to 64x64 or 100x100 true pixel sensors and have small "slow"
wide angle lenses and low video frame rates.

To put that into some context, when I worked on military IR surveillance
kit in the late 80's some of the thermal sensors designed for avionics
use had a thermal telescope on the end of them - all "optics" machined
from germanium, and if memory serves a mildly radioactive coating
applied to the interior surfaces. They started at £150K for the smaller
ones!

A £400 IR camera attachment with a 160 x 120 pixel sensor.
https://www.youtube.com/watch?v=Oiv7sEXL1cI

These systems were higher than SD video resolution in the thermal band -
basically using highly polished video line synched rotating polygons to
project and scan the image onto a fixed SPRITE detector.

https://en.wikipedia.org/wiki/SPRITE_infrared_detector

IR has no colour hence a native B&W video output. This video output is
usually modified to give a false colour output. Everything light grey to
white is rendered white, yellow or red and everything dark grey is
rendered black or blue.Â* The grey scale in between is assigned different
colours.Â* Many different false colour schemes schemes can be used.

False colour seems quite popular in the consumer space, but never really
seemed to be of interest for military or avionics. (you have a choice of
black hot or white hot, and could adjust the gain and offset (the
functional equivalent of contrast and brightness))

--
Cheers,

John.

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alan_m wrote:
Military IR cameras and those commonly becoming available for industrial
or consumer applications operate in the 3um to 5um band or the 8 to
12/14um band. Cameras fitted to the police helicopters are probably the
latter. These cameras most probably have Germanium lenses. To keep costs
low (to perhaps a couple of hundred quid) consumer IR cameras may be
limited to 64x64 or 100x100 true pixel sensors and have small "slow"
wide angle lenses and low video frame rates.

Not just cost, export controls start getting tricky when exporting
higher resolution/framerate models that could be used for military purposes.

A £400 IR camera attachment with a 160 x 120 pixel sensor.
https://www.youtube.com/watch?v=Oiv7sEXL1cI

We have a Flir One gen2 at work - it works reasonably well. Worth noting
that the older gen2 Flir One has a higher thermal resolution (160x120) than
the current gen3 Flir One (80x60) - basically they renamed the $200 One to the
$400 Pro (160x120) and then released a worse $200 new model. Buy an old one
if you can.

IR has no colour hence a native B&W video output. This video output is
usually modified to give a false colour output. Everything light grey to
white is rendered white, yellow or red and everything dark grey is
rendered black or blue. The grey scale in between is assigned different
colours. Many different false colour schemes schemes can be used.

What's nice about the Flir One is there's also a spot temperature
measurement you can bring up, to give you a numeric reading. I don't know
the accuracy (don't have means to measure surface temperature to calibrate
it) but it seems reasonably good.

Theo

On 19/02/2020 17:41, Jim GM4DHJ ... wrote:
On 19/02/2020 12:24, Andrew wrote:
On 19/02/2020 08:43, Jim GM4DHJ ... wrote:
On 19/02/2020 01:23, John Rumm wrote:
On 18/02/2020 19:36, John wrote:
My house was built in 1988. The cavity walls are filled with slabs of
rockwool stuff - possibly not as well as I would have liked.

Occassionally I get salesmen trying to sell me the sort of injected
cavity
wall insulation. They usually claim there is a grant toward it.

I don't like to be pressured - I like to decide if it is a good thing.

At that vintage, chances are they are full fill with solid
insulation batts. So there will be no space for additional injected
insulation.


if they are full they will be the type of batts with vertical
stratification to stop water ingress so don't mess with them ...

Those batts are treated with something to make them water repellent.
STill a valid construction method I believe for properties
not in those parts subjected to heavy driving rain.
they used them in scotland all the time....me?...I like a cavity....

Do you go munro-bagging in a string vest and plimsoles, Rab C Nesbitt-
style ?.